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Published by madison.tfio, 2019-10-30 12:56:57

4R Nutrient Management Study Guide

Final 4R Nutrient Manual FINAL WEB



APRIL 2016

This manual will assist agriculture stakeholders understand and
apply 4R nutrient management planning practices.

Christine Brown, CCA, Ontario Ministry of Agriculture, Food and Rural Affairs
Tom Bruulsema, CCA, International Plant Nutrition Institute
Dale Cowan, CCA, AGRIS and Wanstead Farmers Cooperatives
Susan Fitzgerald, Executive Director, Ontario Certified Crop Advisor Association
Ivan O’Halloran, Ridgetown Campus, University of Guelph
Dale McComb, CCA, Ontario Ministry of Agriculture, Food and Rural Affairs
Keith Reid, Agriculture and Agri-Food Canada
Trevor Robak, Ontario Ministry of Agriculture, Food and Rural Affairs

Appreciation is extended to Fertilizer Canada for their support
in developing this manual and providing graphics and
photographs. The support was provided as part of Fertilizer
Canada’s 4R Memorandum of Cooperation with the Ontario
Ministry of Agriculture, Food and Rural Affairs, and the
Ontario Agri Business Association.

The International Plant Nutrition Institute (IPNI) graciously
provided graphics and shared content from their 4R
publications for use in this guide.

Cover Photo: Courtesy Credit Valley Conservation

Note for Certified Crop Advisors
If this resource guide is being used as a study reference for the 4R Nutrient Management Specialty,
please note that while this guide provides information relevant to each competency area, it should
not be presumed that knowledge of the material in this guide alone is sufficient for the Specialty.
Depending on the background knowledge of the candidate, it may also be necessary to review and be
familiar with the materials identified in the reference list as well.

First Edition

Canadian Certified Crop Advisor Association
All rights reserved

Copies cannot be made without written permission.

The views expressed in the Ontario 4R Nutrient Management Stewardship Guide are the views of the
authors and of the Canadian Certified Crop Advisor Association and do not necessarily reflect those of
the governments of Canada and Ontario.

This project was funded in part through Growing Forward 2 (GF2), a federal-provincial-territorial
initiative. The Agricultural Adaptation Council assists in the delivery of GF2 in Ontario.

Ontario 4R Nutrient Management Stewardship Guide

The Ontario agriculture industry recognizes the importance of environmental stewardship and its role
in ensuring the proper use of crop inputs. The 4R concept of nutrient management has been developed
and is being implemented world-wide by industry, researchers, government agencies, farmers and their
advisors. It is centered on the goal of building a nutrient management plan that puts the right nutrient
sources, at the right rate, at the right time, and in the right place; the 4Rs of nutrient management. It
also considers the economic, social, and environmental dimensions of nutrient management. Because
of these considerations, 4R nutrient management is seen as an essential approach to ensuring the
sustainability of agricultural systems. The 4R concept is simple but its implementation is knowledge-
intensive and site-specific.

Scientific principles guide the development of 4R practices related to source, rate, time and place.
Farmers and crop advisors make sure the practices they select and apply locally are in accord with
these principles. The principles are the same globally, but how they are put into practice locally varies
depending on each farm and taking into consideration their level of agronomic expertise and access to
technology as well as specific characteristics such as: soil, crop type, climate, weather, economics, and
social conditions. The 4R concepts also interact with other plant management practices such as tillage,
irrigation, drainage, crop rotation, cultivar selection, plant protection and weed control.

The 4R nutrient stewardship approach is an essential tool in the development of sustainable agricultural
systems because its application can have multiple positive impacts on increasing food production in an
economically viable way while preserving the environment.

The advantages, at the farm level, of practicing 4R nutrient management are:
• increasing crop production and improving profitability;
• minimizing nutrient loss and maintaining soil fertility; and,
• ensuring sustainable agriculture for generations to come.

The benefits to Ontario agriculture in a broader context include:
• Natural capital benefits: better crop performance, improved
soil health, reduced environmental impacts, and protection of
• E conomic benefits: increase in farmers’ profits and economic
improvement in their communities.
• S ocial benefits: positive public image of environmentally
responsible farming practices, improved rural livelihoods, stronger
farming communities.

The 4R nutrient stewardship concept involves growers and their crop advisors selecting the right
source-rate-time-place combination from practices validated by research and conducted by agronomic
scientists. Goals for economic, environmental and social progress are set by, and are reflected in,
performance indicators chosen by the stakeholders. The resource guide is intended as a support tool in
conveying the principles of 4R within an Ontario context.

For additional copies of this guide, contact:

Certified Crop Advisor Association
39 William Street • Elmira, ON N3B 1P3
519-669-3350 • [email protected] •



Proficiency Area I: Nutrient Management Planning.....................................................................6
Competency Area 1: Roles and Responsibilities of Provincial, Local Public and

Private Entities in Nutrient Management Planning....................................6
Competency Area 2: CCA’s Responsibility in Integrating 4Rs with a Nutrient

Management Plan..............................................................................13
Competency Area 3: Economics of Nutrient Management Planning/Budget for

Operation Changes Due to 4Rs............................................................25
Competency Area 4: Environmental and Social Risk Analysis.................................................29

Proficiency Area II: Nitrogen.....................................................................................................33
Competency Area 1: Determining the Right Source of Nitrogen..............................................35
Competency Area 2: Determining the Right Rate of Nitrogen..................................................41
Competency Area 3: Determining the Right Timing of Nitrogen Application.............................54
Competency Area 4: Determining the Right Placement/Method of Application

for Nitrogen.......................................................................................64
Competency Area 5: Environmental Risk Analysis for Nitrogen...............................................71

Proficiency Area III: Phosphorus................................................................................................78
Competency Area 1: Determining the Right Source of Phosphorus...........................................78
Competency Area 2: Determining the Right Rate of Phosphorus..............................................82
Competency Area 3: Determining the Right Timing of Phosphorus Application..........................87
Competency Area 4: Determining the Right Placement/Method of Application

for Phosphorus...................................................................................90
Competency Area 5: Environmental Risk Analysis for Phosphorus............................................94

4 Table of Contents



Proficiency Area IV: Potassium, Secondary Macronutrients and Micronutrients...........................100
Competency Area 1: Determining the Right Source of Potassium, Secondary

Macronutrients and Micronutrients.......................................................100
Competency Area 2: Determining the Right Rate of Potassium...............................................116
Competency Area 3: Determining the Right Timing of Potassium Application...........................121
Competency Area 4: Determining the Right Placement/Method of Application

for Potassium.....................................................................................122
Competency Area 5: Determining the Right Rate, Timing and Placement of

Secondary Macronutrients..................................................................129
Competency Area 6: Determining the Right Rate, Timing and Placement of Micronutrients........136
Competency Area 7: Determining the Right Rate, Timing and Placement of Lime for

pH Adjustment..................................................................................143

Proficiency Area V: Manure Management.................................................................................149
Competency Area 1: Whole-Herd or Whole-Flock Total Annual Manure and

Nutrient Production............................................................................149
Competency Area 2: Adequacy of the Land Base for Applying Manure..................................154
Competency Area 3: Crediting the Nutrients in Manure for Crop Production...........................156


Please note that while this guide provides information relevant to each 4R
competency area, depending on the background knowledge of the reader, it may
also be necessary to review and be familiar with the materials identified in the list of

references as well. The sources listed were consulted in developing this guide.

Permanently vegetated buffer protecting

the banks of the Credit River

Photo Source: Credit Valley Conservation

Table of Contents 5



Competency Area 1
Roles and Responsibilities of Provincial, Local Public
and Private Entities in Nutrient Management Planning

Performance Objective 1
Interpret a CCA’s roles and responsibilities in nutrient management
planning as described in the following references:

a. N utrient Management Act, 2002 and subsequent revisions,

CCAs should know what their clients require to be compliant under the Nutrient Management
Act, 2002 (NMA). For example, when a farm unit is “phased in” or required to have a nutrient
management strategy, nutrient management plan or NASM plan.

b. N utrient Management Regulation and Protocols,

Regulation 267/03 and the associated protocols set out specific requirements for planning, storage,
and land application standards including maximum application rates and setbacks from wells and
surface and groundwater. It specifically identifies the activities and people to which the regulation
applies and defines the responsibilities and requirements of people impacted by the regulation.

• Built on best management practices.
• S ets a minimum standard across the province (Ontario) for protecting surface and

• R egulations address the production, storage and utilization of land applied materials

containing nutrients.
• D esigned to provide a level playing field across the province.
• Operations are generally “phased-In” dependent upon the requirements based on the number

of animals on the farm, the construction of barns or manure storages, and/or the land
application of NASM.

Nutrient Management Act, e-Laws and other Regulation links:
• Nutrient Management Act, 2002 -
• Nutrient Management Act, 2002, Ontario Regulation 267-03: General
• N utrient Management Act, 2002, Ontario Regulation 300/14: Greenhouse Nutrient

6 PROFICIENCY AREA I - Nutrient Management Planning

• N utrient Management Act, 2002, Ontario Regulation 106/09: Disposal of Dead Farm

Nutrient Management Protocols
• 2 012 Nutrient Management Protocol
- 2012 Nutrient Management Tables
- 2015 Nutrient Management Tables Proposed Updates
• 2015 Greenhouse Nutrient Feedwater Management Protocol
- 2014 Greenhouse Nutrient Feedwater Management Table

NMAN software (AgriSuite) includes the tables referred to in the protocols and flags plans where the
actions will not meet the regulations.

c. Nutrient Management Best Practices,

A Best Management Practice (BMP) is a proven, practical and affordable approach to conserving
resources such as air, water and soil. The key characteristics are:

• practices used on a farm to reduce the potential of causing an adverse effect;
• allows individual assessment of situations or risk and personalized management choices;
• culturally accepted and voluntarily practiced; and,
• scientifically supported.

The Best Management Practices Series can be ordered via the OMAFRA website http://www.omafra. The available Best Management Practices Books are
listed below:

• An Introduction to Best Management Practices
• A First Look
• A Phosphorus Primer
• Agroforestry Series Volume 1 - Woodlot Management
• Agroforestry Series Volume 2 - Establishing Tree Cover
• Application of Municipal Sewage Biosolids to Cropland
• Best Management Practices for Phosphorus
• Buffer Strips
• Controlling Soil Erosion on the Farm
• Cropland Drainage
• Deadstock Disposal
• Farm Forestry and Habitat Management
• Fish and Wildlife Habitat Management
• Greenhouse Gas Reduction in Livestock Production Systems
• Integrated Pest Management
• Irrigation Management
• Keeping Your Well Water Safe to Drink (An Information Kit to Help You Care for Your Well)

Managing Crop Nutrients

PROFICIENCY AREA I - Nutrient Management Planning 7

• Manure Management
• No-till: Making It Work
• Nutrient Management Planning (Revised Edition 2006)
• On-Farm Energy: A Primer
• Pesticide Storage, Handling, and Application
• Self-Assessment and Best Management Practices for Water and Fertilizer Use In Greenhouse

Vegetable Production (Web Only - PDF)
• Soil Management
• Streamside Grazing
• Water Management
• Water Wells

d. International Plant Nutrition Institute (IPNI) 4R Stewardship,

More global in perspective, IPNI initiated the 4R concept through cooperation between the fertilizer
industry and the scientific community. The global framework facilitates the development of site
and crop specific fertilizer BMPs based on sound science. The principles are universal, but their
implementation must be adapted to the local context at different scales.

e. 4R Nutrient Stewardship,

Fertilizer is a component of sustainable crop production systems, and the fertilizer industry recognizes
the need to efficiently utilize these nutrients. This site provides science-based information for
stakeholders to utilize for education, advocacy, and implementation of crop nutrient stewardship. It
provides information on fertilizer best management practices that benefit the environment and the
producer’s bottom line. The site is a collaborative effort of the fertilizer industry.

The guidelines for the 4R principles are endorsed and supported by the International Plant Nutrition
Institute, The Fertilizer Institute, The Canadian Fertilizer Institute, and the International Fertilizer
Industry Association.

f. Fertilizer Canada Nutrient Stewardship,

Fertilizer Canada (operating name for the Canadian Fertilizer Institute) is an industry association that
represents manufacturers, wholesale and retail distributors of nitrogen, phosphate and potash fertilizers.

The Nutrient Stewardship webpage houses Fertilizer Canada’s 4R Nutrient Stewardship programs
across Canada where each project shares a common goal of applying the 4Rs to increase production/
profitability for growers while enhancing environmental protection and improving sustainability for
the region.

For Ontario, there is a 4R Nutrient Stewardship Guidance Document
content/uploads/2016/01/Ontario.pdf. As well, Fertilizer Canada and Ontario partners are working
on a 4R program to directly engage growers in implementing 4R stewardship practices on farm. This
will include a strong role for CCAs employed at the crop input retailer level in working directly
with growers.

8 PROFICIENCY AREA I - Nutrient Management Planning

g. A griculture and Agri-Food Canada – Nutrient Management Planning,

The website has general information on nutrient management planning in the broad sense as well as
best management practices for soil and nutrients.

h. A griculture and Agri-Food Canada – Agricultural Practices,

The website has general information on:
• A groforestry - Benefits of agroforestry practices, best practices for growing trees and how to
plan and establish wind breaks.
• Climate - Information on how changing climate affects agriculture.
• Soil and Land - Soil protection and management.
• W ater - Information on livestock watering, ponds and dugouts, watershed protection, wells
and groundwater.

Uniform application of liquid
manure to a growing crop.

Courtesy Christine Brown

PROFICIENCY AREA I - Nutrient Management Planning 9

Performance Objective 2
Interpret roles and responsibilities of provincial, local public
and private entities in nutrient management planning.

Provincial (government)
• P rovide background information on the Nutrient Management Act (NMA), definitions,
regulations and protocols.
• Provide training and resources for people subject to the regulation.
• Provide certification and training for third parties (consultants/applicators).
• Ensure a timely application approval process.
• Provide inspections and enforcement tools to ensure regulation compliance.
• R egular communication with stakeholders to ensure the regulation is having the
intended impact.
• I ntegrate nutrient management principles into source water protection planning as it relates to
the Clean Water Act for municipal drinking water supplies.

Certificates and Licences
• A gricultural Operation Strategy or Plan Development Certificate (AOSPDC) - This certificate is
for third party individuals (consultants) who prepare nutrient management strategies and plans
for Agricultural Source Materials (ASM) for agricultural operations phased in under the NMA.
• Agricultural Operation Planning Certificate (AOPC) – This certificate is for owners/operators
or farm staff members preparing nutrient management strategies and plans solely for their
• Broker Certificate – Required for those acting as a broker for a transaction involving ASM for
phased-in operations with NMS, NMP or NASM plan.
• Prescribed Materials Application Business (PMAB) Licence – Required for those engaged in the
business of applying materials to agricultural land phased-in with a plan or NASM plan.
• N on-Agricultural Source Material (NASM) Plan Development Certificate – Certificate for
individuals who prepare NASM plans as required by the NMA.
• Nutrient Application Technician Licence – For third party individuals applying nutrients to
agricultural land (phased-in) with a NMP or NASM plan.

Local public (municipal)
• When a nutrient management strategy has been completed and approved, issue building
permit for new buildings that are phased into nutrient management, and ensure building
permit is followed.
• Local Advisory Committees as established under the NMA
• Source water local committees
• Farm source water protection plan

Private (landowner/consultants)
• P rovide required documentation.
• C ertified personnel prepare nutrient management strategies and nutrient management plans.
• Provide required and correct information for documentation required for Nutrient Management
Act and/or Clean Water Act.
• Certified personnel prepare Non-Agricultural Source Materials (NASM) plans for farms
receiving materials.

10 PROFICIENCY AREA I - Nutrient Management Planning

• Landowner follows nutrient management regulations and/or Best Management Practices
(BMPs) using the 4R principles.

• O ntario Environmental Farm Plan - Includes workshops and voluntary self-assessment of farm
practices for every aspect of the farm and Best Management Practices worksheets to help
guide improvements.

Performance Objective 3
Discuss national, province-specific, and local-specific policies
that relate to nutrient management planning.

• Canadian Environmental Protection Act, 1999
• Fisheries Act - Under the Fisheries Act, the federal government regulates water pollution and
prohibits any discharge of a “deleterious substance” into water frequented by fish, and any
works or undertakings that result in the “harmful alteration, disruption or destruction” of
fish habitat.

• M DS (minimum distance separation) for new construction projects. Impacts where a building
is sited based on end use (livestock, odour, manure storage) and the distance separation from
other residences, wells, sensitive features, lot lines, etc.
• Environmental Protection Act (EPA) – General waste management.
• Ontario Water Resources Act (OWRA) - Protecting surface and groundwater.
• Farming and Food Production Protection Act (FFPPA) - Normal Farm Practices. Helps define
normal farm practices including, nutrient management and odour, and has established a
process for normal farm practices conflict resolution and dealing with public complaints
• C lean Water Act (source water protection) – for municipal water supplies. The Ministry of
Environment and Climate Change identified potential threats to municipal water supplies and
set provincial standards for safeguarding those water sources.
• Nutrient Management
- Greenhouse Nutrient Feedwater Regulations (storage, management, land application)
- Requirements for on-farm anaerobic digestion facilities
- Disposal and management of dead farm animals
- Odour guidelines for Non Agricultural Source Materials (NASM)

• Source Water Act – Local source water protection committees were established to develop
the voluntary farm assessment tool designed to address farm practices outside the defined
exclusion zone (100 m well head protection zone or immediate intake point for municipal
surface water). Local “Risk Management Plans” were developed by the Ontario Farm
Environmental Coalition with the intent that they would meet local standards that would exceed
provincial standards.

PROFICIENCY AREA I - Nutrient Management Planning 11

Performance Objective 4
Interpret and understand the certification process under the
province’s Nutrient Management Act and Regulations.

The table below summarizes the certification requirements for individuals preparing a nutrient
management strategy (NMS), nutrient management plan (NMP) or a non-agricultural source material
plan (NASM). A farmer may prepare their own NMS or NMP however a NASM Plan Developer
certification is required for individuals preparing NASM plans.

Table 1.1. Summary of Preparation Options for NMS, NMP and NASM Plans

Options for Certificate requirement Requirements
• Nutrient Management Regulations and Protocols course
NMS or NMP prepared Agricultural Operation • Introduction to Nutrient Management course or equivalent
• Apply for certification
by farmer Planning Certificate
• Introduction to Nutrient Management
NMS or NMP prepared Agricultural Operation • Regulation and Protocols
• How to Prepare a Nutrient Management Strategy and Plan (using NMAN)
by a certified Strategy and Plan • Using NMAN software, complete two fictitious NMPs or NMSs
• Pass an exam
consultant Development Certificate • Apply for certification

NASM Plan prepared NASM Plan Developer’s • NASM Plan Developers Course
by a certified Certificate • Introduction to Nutrient Management course
consultant • NMAN software course
• Complete required assignments and
• Pass an exam
• Apply for certification

Performance Objective 5:
a. Identify responsible parties and their roles in implementing each component

of a Nutrient Management Plan following the Nutrient Management Act.
b. Identify the logistics needed to apply the right source of nutrients at the right

rate, at the right time, and in the right place.

a. Refer to Performance Objective 3 above.
b. Refer to Performance Objective 6 below.

12 PROFICIENCY AREA I - Nutrient Management Planning

Competency Area 2
CCA’s Responsibility in Integrating 4Rs
with a Nutrient Management Plan

Performance Objective 6
Differentiate between regulated Nutrient Management Planning
and 4R nutrient management planning.

Table 1.2 C omparison of Regulated Nutrient Management Planning to
4R Nutrient Management Planning

Regulated Nutrient Management Planning 4R Nutrient Management

Goal • T he goal of nutrient management planning is to manage nutrients to optimize • Goal of fertilizer BMPs is
beneficial use of nutrients for crop production, to minimize environmental to match nutrient supply
Right impacts of nutrients and to identify and manage the areas of risk on with crop requirements and
Source agricultural operations. minimize nutrient losses from
Right • Regulation addresses production, storage and utilization of materials
Rate containing nutrients that can be applied to land.

• Supply nutrients from livestock or non-agricultural sources with analysis to

estimate plant-available nutrients.

• S uit the physical site conditions. Examples include avoiding surface application Matches fertilizer type to crop

of nutrient-rich or phosphorus-containing materials to frozen or snow covered needs

soils, or matching application of materials containing high organic nitrogen to • Placing fertilizer with seed

crops requiring rapid N release. • Looking at nitrogen pathways

• Understand the analysis of the material so that commercial fertilizer • Split fertilizer application

equivalents can be deducted and/or additional requirements can be • S oil sampling to determine

supplemented. needs

• Be aware of contaminants, trace elements and/or salt content of various • Soil pH and nutrient availability

organic amendments (NASM materials) and any restrictions on application rate

or placement (setbacks) that may accompany these materials.

• C alculate plant nutrient demand. Yield is directly related to the quantity of

nutrients taken up by the crop until maturity. The selection of a meaningful

yield target attainable with optimal crop and nutrient management and its

variability within fields and season to season thus provides important guidance Matches amount of fertilizer to
on the estimation of total crop nutrient demand. crop needs
• U se adequate methods to assess soil nutrient supply. Practices may include • Placing fertilizer with seed
soil sampling, plant tissue analysis, response experiments, control plots, etc. • Looking at nitrogen pathways
• A ssess all available nutrient sources. For most farms, this assessment • Split fertilizer application
includes quantity and plant availability of nutrients in manure, compost, • Soil sampling to determine
biosolids, crop residues, irrigation water, as well as commercial fertilizers.
• P redict fertilizer use efficiency. Some loss is unavoidable, however, site needs
conditions at the time of application should be considered to minimize losses • Soil pH and nutrient availability

to the environment. Application of organic materials to encourage loss so that

a higher application rate can be applied is irresponsible. So, to meet plant

demand, that amount must be considered.

PROFICIENCY AREA I - Nutrient Management Planning 13

Table 1.2 C omparison of Regulated Nutrient Management Planning to
4R Nutrient Management Planning ~ Continued

Regulated Nutrient Management Planning 4R Nutrient Management

Right • C onsider soil/crop rotation nutrient balances. If the output of nutrients from a Matches amount of fertilizer to
Rate cropping system exceeds inputs, soil fertility declines in the long term. Often, crop needs
livestock operations with limited land base, apply nutrients in excess of soil/ • Placing fertilizer with seed
Right crop requirements resulting in long-term fertility build-up to levels that increase • Looking at nitrogen pathways
Time environmental risk. • Split fertilizer application
• Soil sampling to determine
Right • Incorporate rate-specific economics. Consider where manure or other organic
Place amendments are applied at specific points in the crop rotation (at rates that needs
include nutrients for the subsequent crop). Avoid application of phosphorus or • Soil pH and nutrient availability
nitrogen above crop nutrient removal. For nutrients unlikely to be retained in
the soil, the most economic rate of application is where the last unit of nutrient
applied is equal in value to the increase in crop yield it generates (law of
diminishing returns). For nutrients retained in the soil, their value to future crops
should be considered.

• Evaluate logistics of farm and field operations. Timing of nutrient applications

should be planned as close to crop needs as possible and at times when the site

and soil conditions are suitable. (i.e. incorporation, low risk of compaction, no rain

in immediate forecast). Nutrient applications should not delay time-sensitive

operations such as planting, in which case more diverse crop rotations that allow

application at alternate times during the growing season (i.e. forages or wheat

with cover crops) may be required. Matches nutrients available

• Assess timing of plant uptake. Nutrients should be applied to match the crop when crops need them

nutrient demand which depends on planting date, plant growth characteristics, • Placing fertilizer with seed

sensitivity to deficiencies at particular growth stages, etc. • Looking at nitrogen pathways

• Assess dynamics of the manure or organic amendment nutrient availability and/ • Split fertilizer application

or when risk of loss is high. Be aware of the nitrogen composition for availability. • Soil sampling to determine

Mineralization of soil organic matter from previous applications can supply a large needs

quantity of some nutrients but if the crop’s uptake need precedes its release, • Soil pH and nutrient availability

deficiencies may limit productivity.

• R ecognize dynamics of soil nutrient loss. For example, leaching losses tend to be

more frequent in the spring and fall. Phosphorus loss can be high with surface

applied material during the non-growing season where risk of runoff and/or

erosion is high.

• E valuate logistics of field operations.

• Assess land base, crop rotation, site characteristics, field fertility levels, equipment Keeps nutrients where crops can
and labour logistics, etc. to plan which fields will benefit most from application of use them
organic amendments • P lacing fertilizer with seed

• Where possible, plan to incorporate nutrients as soon after application as possible control products
(i.e., liquid materials with high ammonium-N or materials with odour) • Looking at nitrogen pathways
• Split fertilizer application
• D etermine where sensitive areas require set-back from material application (i.e. • S oil sampling to determine
water courses, residential areas, municipal wells etc.)
• I n application to no-till fields or fields with living crops, attention to site conditions • Soil pH and nutrient availability
(risk of runoff, preferential flow through tile drains) must be considered to prevent
environmental loss or adverse effect.

• S uit the goals of the tillage system. Subsurface placement techniques that
maintain crop residue cover on the soil can help conserve nutrients and water.

• M anage spatial variability. Assess soil differences within and among fields in crop
productivity, soil nutrient supply capacity, and vulnerability to nutrient loss.

14 PROFICIENCY AREA I - Nutrient Management Planning

Performance Objective 7
Plan the right source(s), at the right rate(s), at the right time(s), and the right
place(s) to fit the client’s cropping system, climate, soils, and farming situation.

Right Source

• S upply nutrients in plant-available forms.

The nutrient applied is plant-available, or is

in a form that converts timely into a plant-

available form in the soil.

• Suit the physical and chemical soil

properties. Examples include avoiding

nitrate application to flooded soils, surface

applications of urea on high pH soils, etc.

• Recognize interactions among nutrient

elements and sources. Examples include

the P-zinc interaction, N increasing P

availability, fertilizer complementing Spring Application of Dry Fertilizer on Winter Wheat.
manure, etc.
Courtesy Christine Brown

• Consider blend compatibility. Certain

combinations of fertilizer types attract moisture when mixed, limiting uniformity of application

of the blended material. Granule size should be similar to avoid product segregation, etc.

• U nderstand the benefits and sensitivities of various fertilizer sources to associated elements.

Most nutrients have an accompanying ion that may be beneficial, neutral or detrimental to

the crop. For example, the chloride (Cl-) accompanying K in muriate of potash is beneficial

to corn but can be detrimental to the quality of tobacco and some fruits. Some sources of P

fertilizer may contain plant-available Ca and S, and small amounts of Mg and micronutrients,

• C ontrol effects of non-nutritive elements. For example, natural deposits of some phosphate

rock contain non-nutritive trace elements. The level of addition of these elements should be

kept within acceptable thresholds.

Right Rate
• C alculate plant nutrient demand. Yield is directly related to the quantity of nutrients taken up
by the crop until maturity. The selection of a meaningful yield target attainable with optimal
crop and nutrient management and its variability within fields and season to season thus
provides important guidance on the estimation of total crop nutrient demand.
• U se adequate methods to assess soil nutrient supply. Practices may include soil sampling,
plant tissue analysis, response experiments, control plots, etc.
• Assess all available nutrient sources. For most farms, this assessment includes quantity and
plant availability of nutrients in manure, compost, biosolids, crop residues, atmospheric
deposition, irrigation water, as well as commercial fertilizers.
• P redict fertilizer use efficiency. Some loss is unavoidable, so to meet plant demand, that
amount must be considered.
• C onsider soil resource impacts. If the output of nutrients from a cropping system exceeds
inputs, soil fertility declines in the long term.
• Incorporate rate-specific economics. For nutrients unlikely to be retained in the soil, the most
economic rate of application is where the last unit of nutrient applied is equal in value to
the increase in crop yield it generates (law of diminishing returns). For nutrients retained in
the soil, their value to future crops should be considered. Assess probabilities of predicting
economically optimum rates and the effect on net returns arising from error in prediction.

PROFICIENCY AREA I - Nutrient Management Planning 15

Right Time
• Assess timing of plant uptake. Nutrients should be applied to match the crop nutrient demand
which depends on planting date, plant growth characteristics, sensitivity to deficiencies at
particular growth stages, etc.
• A ssess dynamics of soil nutrient supply. Mineralization of soil organic matter supplies a large
quantity of some nutrients but if the crop’s uptake need precedes its release, deficiencies may
limit productivity.
• Recognize dynamics of soil nutrient loss. For example, leaching losses tend to be more
frequent in the spring and fall.
• Evaluate logistics of field operations. For example, multiple applications of nutrients may or
may not combine with those of crop protection products. Nutrient applications should not
delay time-sensitive operations such as planting.

Right Place
• Take into account where crop roots are growing. Nutrients need to be placed where they can
be taken up by growing roots when needed.
• C onsider soil chemical reactions. Concentrating soil-retained nutrients like P in bands or
smaller soil volumes can improve availability.
• S uit the goals of the tillage system. Subsurface placement techniques that maintain crop
residue cover on the soil can help conserve nutrients and water.
• Manage spatial variability. Assess soil differences within and among fields in crop
productivity, soil nutrient supply capacity, and vulnerability to nutrient loss.

Performance Objective 8
Evaluate the considerations to plan logistics for the equipment, labor, and nutrient
materials to develop a 4R nutrient management plan for a given operation.

See Table 1.3 in Performance Objective 16 for the basic steps involved in developing, monitoring and
maintaining a 4R nutrient management plan.

When developing a 4R nutrient management plan, consideration has to be given to the feasibility of
implementing the plan. Factors include: crops and varieties to be grown, optimum planting dates
and corresponding nutrient application dates, inventory of available equipment, and manpower hours
required. An assessment must be made regarding the practicality of all field work being handled
within the farming operation or the opportunity to utilize custom operators.

Considering the logistics of the operation can help with 4R nutrient management plan. For example,
increasing opportunities for nutrient/manure application:

• Can manure be applied after planting corn, or after forage harvest or after wheat harvest with
cover crops?

• I f labour or equipment and/or time is a limiting factor (e.g. forage harvest), can utilizing the
services of custom manure application and/or custom fertilizer application be an economic

• Can application during the growing season save on additional storage requirements?

16 PROFICIENCY AREA I - Nutrient Management Planning

If soil fertility levels are already high, and land base for manure is limited, are there opportunities to
trade manure with neighbouring cash crop farms – potentially for straw, labour, equipment, cash, etc.

Performance Objective 9
Discuss the advantages of using soil test interpretations based on accredited soil
tests for making nutrient recommendations.

The Ontario Ministry of Agriculture, Food and Rural Affairs administers a lab accreditation program to
ensure quality control and consistent results for soil tests. The lab accreditation program aims to:

• p rovide a correct analytical result for each soil sample submitted to the accredited labs within
reasonable expectations for each analytical procedure;

• provide consistent results from any of the accredited labs;
• encourage the use of appropriate soil test extractants for which there is a body of fertilizer

response calibration data for Ontario soils;
• p romote the use of accredited labs which perform the standard analyses and perform them

correctly; and,
• promote the use of the fertilizer recommendations based on Ontario research.

In summary, the advantages of using soil test interpretations based on accredited soil tests are:
consistency, reliability, and applicability to your growing area.

Performance Objective 10
Discuss the underlying field research required to calibrate a given soil test
extraction method, i.e. to derive nutrient recommendations from the test values.

The choice of an extractant is specific to each region since the most appropriate extractant will depend
to a large extent on the soils of that region. The first step in determining an appropriate extractant or
soil test method is to collect samples of a wide range of soils from across the region and then to grow
plants in each soil. These plants are harvested, weighed and analyzed to find the amount of nutrient
taken up by the plants from the different soils. Different extractants are used to remove the nutrients from
the soils and the extracts are analyzed. The final step compares the results of the extractions with the
amount taken up by the plants which is the measure of the nutrient-supplying capacity of the soil. The
extractant chosen for a region is normally the one with the highest correlation to the plant uptake.

PROFICIENCY AREA I - Nutrient Management Planning 17

Performance Objective 11
Justify management actions that should be considered if nutrients
need to be applied outside the optimum 4R nutrient management plan.

The 4R nutrient management plan will cover nutrient source, rate, timing and placement. Inclement
weather, equipment breakdown, and market availability of crop inputs can impact the implementation
of the optimum plan.

If a particular nutrient source is not available or becomes less desirable due to pricing, other sources
may be considered taking into account the nutrient requirements of the crop, type of application
equipment required, crop growth stage, and crop conditions.

The application rate of nutrients should be managed to match crop needs based on current soil test
results and crop production plans. The over application of nutrients, higher than needed for crop
response, can lead to increases, or buildup, of soil test levels and also directly increase risk of nutrient
loss, particularly when the source is surface applied without incorporation.

In the case of manure management on livestock and poultry farms, if nutrient rates are at the maximum,
some alternatives include: finding a manure broker who could take the excess nutrient, finding a
neighbor (e.g. cash cropper) who might accept the excess nutrient.

Some nutrients are ideally applied in split applications however weather factors may necessitate
changing to a single application or utilizing a different method of application. If the timing of nutrients
changes significantly so that the crop has progressed to a different growth stage, both the nutrient
source and application method/placement may have to be changed.

Refer also to the individual nutrient chapters in this guide for more detailed information on factors to be
considered for each nutrient.

Performance Objective 12
Discuss consequences of increasing soil nutrient levels above
the crop nutrient response level.

As nutrient levels increase, yields will likewise increase until nutrient levels become excessive and
then yields will begin to decline. In most cases, maximum economic yield is also the point where
the plant is making the best use of the fertilizer. Using excessive rates reduces profitability for the
farmer and directly increases the risk of nutrient loss particularly when the source is surface applied
without incorporation. This can lead to an increased environmental risk for surface or groundwater

As noted above, increasing fertilizer application rates might even result in crop yield loss. For
example, too much nitrogen fertilizer results in excess vegetative growth which reduces the reproductive
growth which is needed to maintain large yields of seed, grain, or fruit. A thick vegetative canopy
promotes disease by slowing drying leading to higher costs for disease control. It can also lead to
lodging and associated yield loss.

18 PROFICIENCY AREA I - Nutrient Management Planning

Excess nutrients can also affect crop quality especially in horticulture crops. In apples, excess nitrogen
can result in soft fruit with poor color. In grapes, it will delay ripening.

Excessive nutrients can interact with the availability of other nutrients potentially causing deficiencies or
toxicities. For example, too much potassium can cause bitter pit in apples by interfering with calcium

For crops grown for animal feed, care must be taken that applied nutrient levels do not negatively affect
the nutrient content of the resulting feed. For example, excessive soil K will reduce magnesium uptake
in forages, this may be a health concern when livestock consume forages testing low in Mg.

Performance Objective 13
Evaluate a CCA’s professional risks and responsibilities related
to nutrient management planning.

Providing agronomic advice related to nutrient management planning carries the same professional
ethics requirements and legal responsibilities as other types of business advice. CCAs must avoid and
discourage sensational, exaggerated, or unwarranted claims or recommendations that might encourage
growers to participate in unsound practices. CCAs should not give a professional opinion or make a
recommendation without being as thoroughly informed as possible regarding the products, practices
and services being recommended and the individual client’s/customer’s farming operation.

Regardless of the particular service rendered or the capacity in which a CCA functions, advisors should
protect the integrity of their work, maintain objectivity and disclose any material conflicts of interest (i.e.
recommending products or services from which the CCA or their employer may receive financial gain).
CCAs should also recognize the limitations of their individual knowledge and when consultation with
other professionals is appropriate or referral to other professionals necessary.

The best interest of the client/customer is protected by recommending only products and services that
are beneficial to the client while taking into account and complying with legislation and regulation.
Public good may also be a key factor in terms of environmental stewardship.

PROFICIENCY AREA I - Nutrient Management Planning 19

Performance Objective 14
Discuss the components of a 4R nutrient management plan that should be
monitored and tracked over time and the impacts of any changes.

• Cropping records should document by field: crops and varieties planted, planting date,
seeding rate, date and rate of nutrient applications, date and rates of herbicide and
insecticide applications, harvest date, and yields.

• Detail current management practices, e.g. type of tillage system, application practice and/or
equipment, etc.

• Soil and manure test results.
• Soil quality in terms of structure, texture, compaction, erosion, etc. should be noted and

corrective action taken if negative trends are seen.
• L ivestock records, if applicable, including the type of livestock on farm, number of head

broken down by age groups, any significant changes in feeding regime and/or ration.
• Water quality in wells and tiles.
• Any mitigation measures implemented, e.g. buffer strips, windbreaks, water and sediment

control basins, etc.,

Refer also to Table 1.3 in Performance Objective 16.

Performance Objective 15
Analyze various changes in the farm operation that will require updates or
adjustments to a 4R nutrient management plan such as:

a. cropping system or rotation;
b. soil test results;
c. livestock housing or animal numbers;
d. application rate;
e. yields.

Cropping System or Rotation
When changing crops during the growing season, nutrient amounts and fertilizer formulation should
be adjusted to account for a change in crop. If the nutrients have already been applied, the amount
and formulation should be adjusted for the next crop where possible, to account for the nutrient needs
and removal for the current crop. However, a change in crop grown won’t have that much impact on a
plan over the whole crop rotation.

Soil Test Results
A proper soil test will help ensure the application of enough fertilizer to meet the requirements of the
crop while taking advantage of the nutrients already present in the soil. It will also help determine
lime requirements and can be used to diagnose problem areas, e.g. high or low pH, problematic
soil texture, adverse nutrient levels, etc. These results can be useful for guidance in management or
remediation decisions.

20 PROFICIENCY AREA I - Nutrient Management Planning

Soil test results taken over time illustrate changes in soil properties. This is useful to track remediation
efforts or determine if unfavorable trends are occurring. Proper management of nutrients balances the
requirements of the crop being grown, the nutrients already available in the soil and the proper timing
and placement of nutrient additions for the greatest crop response and the least environmental impact.

Livestock Housing or Animal Numbers
Take manure samples annually for three years for new facilities, followed with samples every three
to five years, unless animal management practices change. The type and age of livestock, feeding
ration, bedding, added liquids and storage system all affect the final nutrient analysis of the manure.
Phosphorus tends to be concentrated in the solids, while potassium levels tend to be higher in the liquid
portion, therefore the level of agitation will also affect nutrient levels being applied to a field.

Application Rate
Changes in the application rates of nutrients may impact soil test levels and/or nutrient availability
for the current and subsequent crop. If the timing of nutrient application is changed, e.g. due to
unfavourable weather, adjust nutrients applied to reflect the change in time. For example, if changing
from a fall manure application to spring application, adjust commercial N to reflect the higher N
availability from the manure. Adjust subsequent applications of nutrients to accommodate the change in
timing of the nutrient application and record the change in the nutrient management plan.

Nutrient recommendations should always
be based on a soil test. If the previous
year’s yields were lower than expected due
to weather or other unforeseen factor, the
need to calculate carryover or a credit is
not necessary. If fertility was not removed,
then the soil test values should be higher
reflecting the need for lower rates of
application going forward. Conversely,
higher nutrient removal by the previous crop
will be reflected in lower soil test values. A
higher yield target may require changes
to nutrient recommendations to meet crop

Ontario Agricultural Planning Tools Suite for Nutrient Management Planning.

Courtesy Dale McComb

PROFICIENCY AREA I - Nutrient Management Planning 21

Performance Objective 16
Demonstrate knowledge of plan implementation, follow-up, and
record keeping components of a 4R nutrient management plan.

Table 1.3 Basic Steps in Developing and Maintaining a 4R Nutrient Management Plan

Steps Description Key Components

1 State your direction for nutrient management planning – • Establish why you’re doing the plan
Set goals helps with decision-making • Seek advice
• Evaluate land base needs (expanding, more/less rented • Create a vision for what the plan will accomplish
Take acreage etc.)
inventory • Optimize economic yields
• Manage input costs
3 • Manage available equipment and/or labour for required
Input and
analyze field operations
• Protect soil and water resources
data • Comply with regulations
4 • Use of custom work for all or portions of field work
• Consider other stakeholders (neighbours, general
public, farm associations etc.)

• Identify resources on the farm

• Describe site characteristics

• Detail current management practices

• Farm map that includes all fields, and includes wells,

catch basins, open drains, streams, rivers, and other

environmentally sensitive areas (source-water -

municipal wells - groundwater time of travel restrictions)

Create a picture in time of what’s currently available • W hat are the available nutrients on the farm? E.g. manure

within your operation – if you don’t know what you’ve got, nutrients or off-farm nutrient sources, nitrogen credits

you don’t know what you need from legumes, commercial fertilizer already applied at a

different point in rotation

• Interpreted soil test information for each field (based on

information provided from regular testing)

• Site characteristics that will/could impact the timing or

placement of nutrients, risk of leaching, risk of runoff, etc.

• Crop inventory and realistic yield goals (backed up with

historical averages)

Apply what you have against what you need to do. • Use NMAN and MSTOR
• Determine the amount and type of nutrient sources

available for use at an operation
• Use soil test information and intended crop types and

yields to determine the amount of nutrients needed
• Determine land base requirements
• Conduct risk assessment

Based on your data analysis, develop options – to manage • List possible management practices

risk, decrease input costs, and handle all nutrients • Identify changes to structures and facilities, equipment

generated. • Remember the systems approach

22 PROFICIENCY AREA I - Nutrient Management Planning

Table 1.3 Basic Steps in Developing and Maintaining a 4R Nutrient Management Plan ~ Continued

Steps Description Key Components

5 • Consider personal and business goals
Make Select options to meet your goals • Use available resources
decisions • Set proper application rates
• Honour separation distances
6 “Walk the talk” to meet your goals
Act • Make an operational plan
• Complete day-to-day activities
7 Document what actually takes place – develop your • A ccount for the impact of outside forces, e.g., weather,
Keep own information for future planning, while showing
records accountability for your actions markets

8 Observe the impact of what you do to determine: For each field, for each farm, maintain:
Monitor • Is production on track? • application records;
• Is ground and surface water protected? • livestock records;
• Are nutrients cycling properly? • cropping records;
• monitoring records
9 Fine-tune your plan, and upgrade technology where
Adjust appropriate. Records should include:
• n utrients applied and application method (equipment,
Plan Develop a contingency plan. Consider/document the depth); and
for the “what would I do if….?” • D ate applied and soil and weather characteristics, crop
growth stage, etc.
Chart adapted from Best Management Practices, Nutrient Management Planning, 2006, p. 31 • yield and quality

• N utrient levels in soil and manure as it relates to crop

• Water quality in wells and tiles.
• Livestock performance
• Nuisance impacts
• U se performance indicators that include soil fertility

levels, nutrient use efficiencies, crop balances, yield,
economic yield, change in 4-R principles (such as how
many acres had all fertilizer banded or immediately
incorporated and how does that compare to base-line

• Use information from record keeping and monitoring
• Modify plan by repeating Steps 3 to 8

• Identify resources
• Communicate to others involved
• Document actions.

PROFICIENCY AREA I - Nutrient Management Planning 23

Performance Objective 17
Discuss the record keeping responsibilities and the follow-up process with the
operator/client and any or all parties involved with components of the plan.

A 4R nutrient management plan is considered a living document that is revised and refined as
circumstances change and as more information and knowledge is acquired. Table 1.3 above outlines
the various steps involved in developing a 4R nutrient management plan. Ideally, the client would
enlist the support of their agronomic advisor during the first stage to assist with detailing current crop
management practices, e.g. type of tillage system, application equipment, etc. and setting targets
for soil health, water management, crop yields, etc. Advisors may be involved in soil and manure
sampling and providing interpretation of the results.

Typically, a crop plan would be developed in the fall or early winter prior to the growing season. The
plan should be reviewed once the spring planting season approaches or gets underway and may
have to be adjusted due to weather, market fluctuations, product availability, or other factors. Further
adjustments in the implementation of the plan may be required and advisors should periodically touch
base with their grower customers over the course of the growing season. Any revisions to the plan
should be recorded.

After harvest, the year’s results should be reviewed and analyzed prior to developing a plan and setting
targets for the subsequent year. When reviewing or making changes to the plan, take into account:

• crop yields and response;
• soil test results that may show nutrient levels changing over time;
• manure sample analysis that may vary;
• new technology that may influence application rate or timing;
• m arket fluctuations that may impact the livestock raised, crops grown, end use of products

generated, acres of various crops, rotational mix, etc.;
• greater understanding of soils and water quality principles;
• purchase or rental of additional land base or, conversely, the divesting of land;
• p ersonal or personnel changes that may affect the grower’s long-term goals, labour

availability, etc.; and,
• c hanges in the community (e.g. urban growth closer to the farm), bylaw changes and new

regulations that may affect farming practices.

Performance Objective 18
Discuss the advantages of maintaining consistent field map boundaries and field
numbering systems with government agencies, the client, and the consultant.

Maintaining consistent field boundaries and numbering ensures that results can be compared year
over year, e.g. application rates and products applied, yields, soil test trends, evaluation of crop
varieties and practices, etc. It also provides a common reference for growers, their employees, service
providers, and government agencies. This could avoid the negative consequences of a product or
practice being applied to the wrong field, e.g. glyphosate being applied to a non-tolerant variety. If the
crop is grown for human consumption or a specialty market, individual field identification and tracking
of operations on/in that field may be a requirement for a traceability program.

24 PROFICIENCY AREA I - Nutrient Management Planning

Competency Area 3
Economics of Nutrient Management Planning/Budget
for Operation Changes Due to 4Rs

Performance Objective 19
Construct an enterprise budget for each crop production system1.

Choosing what crops or livestock to produce is an essential decision of any farm business. One critical
factor in making that decision is the cost of producing the “enterprises” being considered. This is known
as enterprise budgeting or cost of production budgeting. Enterprises are a single crop or livestock
commodity that produces a marketable product. Cost of Production (COP) budgeting consists of
estimating the costs associated with an enterprise and the expected revenue.

While the format of COP budgets can vary they typically include the following sections.
• Revenue: the gross revenue from crop or livestock sales before any expenses have been
• D irect Variable Costs: expenses for the production of a specific commodity. These change
depending on the level of production (e.g., seed, fertilizer, pesticides and feed).
• Indirect Variable Costs: expenses used in producing all commodities on the farm
(e.g., fuel, labour and utilities). These also change depending on the level of production.
• Fixed Costs: expenses that remain the same regardless of the level of production
(e.g., property taxes, fire insurance and depreciation).
• Net Profit (loss): revenue minus all variable and fixed costs.

If possible, review the cost of production for each individual enterprise for the past three to five years.
This shows how much each is contributing to the whole farm financial picture, illustrating which
enterprise is making money and which is not.

Pricing targets for inputs and outputs can be set at different cost breakeven levels. Know your
breakeven points. This information allows you to take advantage of buying or selling opportunities
when they arise. Use the following formulas to determine breakeven points.

Breakeven price to cover variable costs
Total variable costs ÷ Expected yield = $ / unit produced
This is the minimum price needed to cover variable costs.

Breakeven price to cover total costs
Total costs ÷ Expected yield = $ / unit produced
This is the minimum price needed to cover all costs.

Breakeven yield
Total costs ÷ Expected price = Unit produced
This is the minimum yield needed to cover all costs.

The difficulty many farmers have in COP budgeting is allocating whole farm costs to a specific
enterprise. And the more enterprises there are, the more difficult the allocation process.

1. Answer adapted from Guide to Cost of Production Budgeting, Ontario Ministry of Agriculture, Food and Rural Affairs, Factsheet 08-055, 2008.

PROFICIENCY AREA I - Nutrient Management Planning 25

Use the three main approaches to estimating enterprise costs: using on farm records, market value
information and formula based. A formula-based approach is particularly useful for estimating capital
costs associated with farm machinery and buildings. This method takes fuel use and repair rates,
replacement costs and years of expected life to insert into formulas that calculate annual variable and
fixed costs.

OMAFRA has budgeting tools available for a wide variety of farm enterprises on their website at

See OMAFRA Factsheets Budgeting Farm Machinery Costs, Order Number 01-075 and Lease
Agreements for Farm Buildings, Order Number 03-095, for detailed information and tables to calculate
machinery and building costs using the formula-based approach.

The American Agricultural Economics Association (AAEA) has guidelines for COP budgeting available
in their publication Commodity Cost and Returns Estimation Handbook. This handbook is available at
the United States Department of Agriculture’s Natural Resources Conservation Service website at:

Performance Objective 20
Evaluate changes in benefits, costs and risks of
implementing 4R practices including:

a. changing fertilizer application methods;
b. changing forms of nutrients;
c. freight (logistics of handling fertilizer products);
d. use of stabilizers and additives;
e. risk of timing changes;
f. yield increases;
g. alternate cropping systems;
h. crop insurance (regulations and premiums).

Changing Fertilizer Application Methods
• Changing application method can help to match timing of application to the timing of growth
• Different application methods may be better adapted to the overall crop management system,
and the efficiency of use of labor and equipment resources.

Changing Forms of Nutrients
• T he risk of nutrient loss can be significantly reduced, or increased, depending upon which
forms are used, and depending upon soil types and weather conditions. Match the form used
with the soil type and the expected weather.
• There may be a large differential in the costs when switching from one form to another.

26 PROFICIENCY AREA I - Nutrient Management Planning

• Taking a whole farm approach to nutrient management, e.g. accounting for all nutrients
available in the soil, manure, etc., allows recycling of nutrients over the entire land base,
supplying crops with commercial nutrients only when and where required.

Freight (logistics of handling fertilizer products)
• H auling distance, storage needed, and equipment available all must be included in the
decision of which products and forms are selected.

Use of Stabilizers and Additives
• Stabilizers and additives can be used to reduce risk and costs of losses of N.
• They may allow reduced application rates.

Risk of Timing Changes
• Shifting from fall-applied N increases the risk that unfavorable spring weather will delay or
prevent spring application.
• S hifting to split or multiple applications increase total application costs and labor expenses.

Yield Increases
• Crop yields are important because they help determine fertilizer recommendations for a
given crop.
• Y ield also helps estimate the nutrients removed from the field. In nutrient management
planning, when soil fertility levels are high, application rates are determined by matching rates
with nutrient removed by the crop. Higher yields may reflect greater nutrient removal from the
soil and thus a higher application rate for the subsequent crop.

Alternate Cropping Systems
• Alternate cropping systems that include a more diverse crop rotation can result in additional
opportunities for 4R practices and can spread risk/benefits over more crops. Alternate tillage
systems (e.g. moving from conventional to no-till) can improve soil characteristics and reduce
erosion, but requires a transition period.
• A change in cropping systems may involve the purchase or lease of different equipment and/
or technology or custom application services.
• There may also be additional labour requirements however, the reverse could also be true
where there is a labour saving component.

Crop Insurance (regulations and premiums)
Crop insurance reduces the financial risk of perils. 4R stewardship and other good management
practices will help reduce the impact of crop failures or other insurable events. For example:

• Severe rain events will result in less nutrient runoff if fertilizer is incorporated below the soil

• Yield loss due to moisture stress (drought) will be less severe in soils with higher organic matter
and water holding capacity.

• A dequate soil fertility and crop management can reduce the impact of winter kill in alfalfa
forage crops and winter wheat.

• Water management (including tile drainage, grassed waterways, WASCoBs – water and
sediment control basins, etc.) can reduce the amount of time that soils are saturated and water
ponds on fields which can reduce crop loss and nutrient loss.

PROFICIENCY AREA I - Nutrient Management Planning 27

Performance Objective 21
Evaluate the incremental expected changes in
revenue from adopting the 4R practices.

Basically, developing and implementing a 4R nutrient management plan should lead to greater
efficiency in terms of nutrient use. Conducting soil tests and analyzing manure samples may result in
growers finding that there are many nutrients present but unaccounted for in their operation’s manure
and soil. By maximizing the efficiency of use of all sources of nutrients within a farming operation, the
grower may be able to reduce fertilizer or fuel costs. Sampling and record keeping may also lead to
more efficient use of nutrient sources in terms of timing and method of application. Matching applied
nutrients to crop needs and goals could increase yields and/or crop quality leading to increased

Performance Objective 22
Estimate the costs for nutrient management plans including: plan preparation,
record keeping, soil tests, manure tests, and labour.

Many 4R practices do not significantly increase production costs. They mostly involve shifting timing
or placement. Some changes in inputs require increased costs, but, if carefully selected, they should
also increase yields and thus increase income. There are laboratory costs associated with having soil
and manure samples analyzed, however they are easily offset by savings in commercial fertilizer or by
ensuring adequate crop nutrition.

Performance Objective 23
Estimate the financial risk or exposure of not following a
4R nutrient management plan.

Growers may apply more nutrients than required which would increase expenses in terms of fertilizer
purchased and potentially higher fuel and labour costs if unnecessary applications occurred. This could
also negatively impact crop yields and crop quality.

Excess application of nutrients can also lead to the degradation of surface and groundwater through
nutrient loss.

If surface or groundwater is negatively impacted as a result of direct action taken by the farming
operation, there is the potential for the operation to face legal action. Likewise, if manure is handled
in contravention of the requirements of the Nutrient Management Act, the farm operator or manure
applicator could face charges and fines.

28 PROFICIENCY AREA I - Nutrient Management Planning

Performance Objective 24
Evaluate the potential financial impact (costs and revenues) to an operation of the
short-term and the long-term changes required by a 4R nutrient management plan.

4R nutrient management planning helps to:
• optimize use of on-farm nutrients;
• prevent excessive nutrient build-up;
• reduce fertilizer costs;
• maintain soil health for successful crop production; and,
• reduce environmental risks.

Managing nutrients properly offers both economic and environmental benefits to producers and the
rest of society. Efficient use of nutrients from commercial fertilizers, manure or other sources reduces
input costs for crop production and minimizes the risk of nutrient loss to ground and surface water.
With rising fertilizer and fuel prices, as well as concerns for environmental stewardship, sound nutrient
management is increasingly important for the sustainability of crop and livestock operations.

Competency Area 4
Environmental and Social Risk Analysis

Performance Objective 25
Justify why nutrient management is important to the environment and public health.

Agriculture is one of the sources of nitrogen and phosphorus pollution of water in rural areas. Crop
nutrients leaving farmland can pollute water. Concentrations of these nutrients in water above tolerable
limits can be harmful to humans, livestock and wildlife.

In unpolluted fresh waters, aquatic plant growth including algae is limited by the low level of
phosphorus. Phosphates either dissolved or bound to soil particles, can run off land to surface waters
such as drainage ditches, streams and rivers. In Ontario, algal growth has periodically made the water
in some lakes and rivers unsuitable for drinking or swimming. It has also lead to the death of fish and
other aquatic animals from the lack of oxygen in the water.

Nitrate and ammonium are the two forms of nitrogen considered to have an impact on water quality.
Nitrate-nitrogen can leach into groundwater. Young mammals, including people, are susceptible to
health effects of high-nitrate drinking water. Consuming water with high nitrate concentrations can
cause severe illness or reduce livestock performance. Nitrogen in the ammonia form is very toxic to
fish. Contamination of surface water with materials containing large amounts of ammonia can kill
large numbers of fish.

Greenhouse gas (GHG) emissions can also be increased with fertilizer and manure use. Nitrous oxide
(N20) is almost 300 times more damaging than carbon dioxide C02 and is at highest risk for loss when
nitrate levels are high and soils are cool and saturated. Applying nutrients as close as possible to crop
needs at the rate required by a crop is the best 4R strategy for reducing GHG emissions

PROFICIENCY AREA I - Nutrient Management Planning 29

Performance Objective 26
Discuss why environmental risk analysis is an important
component of nutrient management planning.

In the recent past, greater societal awareness regarding water quality and a better understanding of
how nutrients cycle though the environment have put the spotlight on all on-farm nutrients. Nutrient
management planning helps match the nutrient requirement of the crop with the nutrients available
from the soil and those supplied to the crop through application materials containing nutrients such as
fertilizer and livestock manure.
Reducing the risk of contamination from a property takes careful planning. A first step in planning is
determining what site specific characteristics are present and what risk they pose. The potential for
groundwater contamination once a contaminant enters the soil varies from farm to farm and depends
on many factors. An environmental risk assessment enables a farmer to address the specific risks that
exist on their farmstead that are presented by the storage, handling and application of nutrients.

Injecting Liquid Manure. Courtesy Christine Brown

30 PROFICIENCY AREA I - Nutrient Management Planning

Performance Objective 27
Discuss the importance of social and interpersonal
concerns in nutrient management planning.

The nutrient management planning process addresses the storage, handling and application of farm
nutrients such as manure and fertilizer in a way that is demonstrable and shows due diligence. The
aim is to protect rural soil and water, and give farm operators clear instruction on what they need to do
to manage nutrients responsibly and meet legislative requirements.

Farmers and their non-farming neighbours have a vested interest in local soil and water quality.
Both want their community to thrive economically. Both prefer a rural way of life. And like people
everywhere, they value harmonious relations with their neighbours.

Nevertheless, conflicts do arise. These days many farms need to expand, specialize and adopt new
technologies if they are to succeed. Increasingly they are surrounded by relative newcomers who
have migrated from urban areas in search of a pastoral lifestyle in the countryside. These and other
concurrent trends seem tailor-made to generate misunderstandings.

Farmers should be proactive in establishing communication channels with their neighbours. The best
approach is an informal one that brings farmers, neighbours and the greater community together to
talk, listen and build mutual respect and trust - long before conflicts take on a life of their own.

Making demonstrable efforts and using recognized practices to protect soil, water and air quality
on cropland, along water bodies, and in and around farm buildings is a farmer’s best defence.
While adopting best management practices is important, they do little to pacify neighbours who do
not understand or appreciate the efforts and investment you are making in environmental quality or
agriculture’s contribution to the economy in general. Simple one-on-one conversations can do much to
prevent problems.

It is important to reinforce these conversations with comprehensive planning. These planning efforts
demonstrate proactive environmental stewardship and reflect well on the farmer and the agriculture
sector. Producing high quality products in an environmentally responsible manner generates consumer

For example, odour concerns:
• Farming operations can generate odours. Odour complaints form the majority of complaints
directed to farmers.
• Farmers who have conflict-avoidance strategies receive fewer complaints.
• Developing good communication within the rural community can reduce the number and
magnitude of complaints

PROFICIENCY AREA I - Nutrient Management Planning 31

Performance Objective 28
Discuss how regulatory requirements may
supersede the results of a risk assessment.

In Ontario, the nutrient management regulation (O. Reg. 267/03) sets a base level of environmental
protection which farmers must maintain. Many of the regulations are based on historic best
management practices that have been generally accepted and voluntarily adopted by livestock

Sometimes these regulatory standards may be more protective than a simple risk assessment might
indicate. For example, a farmer may be accustomed to spreading the manure generated by their
operation in November and in April. A risk assessment may indicate that they require only 180 days
(six months) of storage capacity for the manure generated at this farm. In Ontario, most farms that
construct new or expand existing livestock housing or manure storage must have the capacity to store
all of the manure generated by the operation for 240 days.

If there is a conflict between the result of a risk assessment and a regulatory requirement, the producer
must follow the regulatory requirement.

Performance Objective 29
Interpret how to use soil test results in environmental risk analysis.

A fundamental part of any nutrient management plan is determining how much nutrient is already
present in the soil. Only then can a plan be developed to properly manage the nutrients that have
been generated on farm as well as nutrients that are being imported onto the property as biosolids or
commercial fertilizer.

When nutrients are applied in excess of crop utilization, then over time, nutrient levels will gradually
build up in the soil, or move out of the root zone.

Soil test results show the level of nutrient in the soil. As part of a risk assessment, consider:
• U se soil test levels to target nutrient application where that nutrient can provide the most
• L ow testing field require more nutrients. Higher application rates may present risk of offsite
movement of material. Adopt management practices to keep the material in place.
• H igh testing fields may not require any additional nutrient. If nutrients are to be applied to a
field where the nutrient level is already high, consider a different nutrient source, a lower rate
and/or adopt management practices that ensure that the nutrients do not cause environmental

32 PROFICIENCY AREA I - Nutrient Management Planning



Introduction to the Nitrogen Cycle

A basic understanding of the N cycle is required to appreciate the impact N fertilizer management
decisions and environmental conditions have on the fate of that applied N. The N cycle describes
the forms of N found in, added to and lost from the soil, and the transformations that these N forms
undergo. Many of the transformations are carried out by soil organisms or plants, and therefore these
changes are affected by environmental conditions such as soil temperature and moisture content.

Source: International Plant Nutrition Institute

The amount of organic N in the soil is quite large. Soil organic matter typically has a C:N ration
of 10:1 to 12:1. In just the top 15 cm (6”) of soil, there is approximately 1,000 kg ha-1 of
organic N for every 1% of soil organic matter.


Soil N exists primarily in three forms or pools of N: organic N, and two mineral forms - ammonium
(NH4+) and nitrate (NO3-). The mineral N forms are the ones absorbed by plants. By far the soil
organic N pool is the largest, representing over 90% of the N in the soil. Organic N in the soil arises
from biological fixation of N by rhizobia in legume plants or by free-living soil organisms, the return of
plant residues to the soil, the addition of organic amendments to soils such as animal manure or non-
agricultural source materials (NASMs), and through the immobilization of mineral N in the soil by soil
When microorganisms consume (decompose) organic matter, they can either utilize the N in that
organic matter for their own needs or, if N is in excess of their requirements, release the N into the soil
as NH4+. This process is referred to as mineralization as the N is converted from an organic form to
a mineral form. The NH4+ can meet several fates: it is soluble and thus remains in soil solution and
can be subjected to leaching but since it is a cation it can be held on the soil cation exchange capacity
(CEC) so leaching is usually only a problem in soils that leach quickly and have a low CEC (e.g. sandy
soils); it can be fixed inside certain clay minerals (known as NH4+ fixation) which greatly diminishes
its plant availability; it can be taken up (immobilized) by other soil organisms or plants; at higher
soil pH values more of the NH4+ in solution is found as ammonia (NH3) which can volatilize into the
atmosphere from the soil; and certain soil organisms can convert the NH4+ to nitrite (NO2-) and then
NO3- through a process called nitrification. Nitrite is very toxic, and is not usually found in soils due to
the fact that the formation of NO3- is considerably faster than the formation of NO2-. The conversion of
NH4+ to NO3- is called nitrification and is fairly rapid in moist, warm soils.
Nitrate is very soluble and since it is an anion (negatively charged) it is not held by soil particles and
therefore prone to leaching. Like NH4+, NO3- can be immobilized by plants and soil microorganisms
where it eventually becomes organic N. In poorly drained or anaerobic soils, groups of soil
microorganisms use NO3- anion as an oxidizer converting it to various forms of N oxides and N gas.
Complete denitrification to N gas (N2) is not an environmental concern as approximately 78% of the
atmosphere is N2 gas. Incomplete denitrification, however, can result in the loss of a potent greenhouse
gas, nitrous oxide (N2O), from the soil.
Other additions of N to the soil typically occur as the three forms found in the soil. Organic sources
of N are urea, animal manures and non-agricultural source material (NASMs). Ammonium is added
to soils in animal manures, some NASMs and as commercial fertilizers. Nitrate is not found in any
significant quantities in animal manures but may be found in some NASMs. Nitrate is also added
naturally to soils through lightning and rainfall.


Competency Area 1
Determining the Right Source of Nitrogen

Performance Objective 1
Discuss the most common sources of nitrogen used in Ontario.

Urea (46-0-0)
• CO(NH2)2
• white solid
• p roduced synthetically from ammonia and carbon dioxide under conditions of high pressure
and temperature
• most commonly used fertilizer N source worldwide
• m ay contain small amounts (0.5% - 1.5%) of biuret, about 0.3% conditioning agent
(formaldehyde or methylene di-urea) and less than 0.5% moisture
• g rades for foliar application should contain less biuret

Urea reacts with water (hydrolyzes) to form ammonium (NH4+) and bicarbonate (HCO3-) in the soil.
The urease enzyme (present in soils, bacteria and crop residues) speeds the process. Surface-applied
urea is subject to losses of ammonia through ammonia volatilization. Losses increase with higher
soil pH (which can also be increased due to urea hydrolysis), more crop residues and with higher

Ammonium nitrate (34-0-0)
• NH4NO3
• white solid
• produced by combining ammonia with nitric acid
• may contain about 1% conditioning agent and 0.5% moisture
• more expensive per unit of N than urea
• no longer produced in Canada
• regulations apply to its transport (Transport of Dangerous Goods Class 5.1)
• n eeds to be kept away from oils and other flammable materials as it can form an explosive
• more hygroscopic than urea and may deteriorate in storage during hot weather as crystal
phase changes result in a breakdown of the prills

When applied to the soil, ammonium nitrate dissolves in the soil water and separates into ammonium
and nitrate, both of which can be absorbed by plants. It is slightly more quickly available to plants at
low temperatures than urea but, under normal growing conditions, there is no practical difference.

Calcium ammonium nitrate (27-0-0)
• uniform mixture of 80% ammonium nitrate and either calcitic or dolomitic limestone
• grey-white solid
• limestone reduces explosion hazard

When applied at equal weights of N, calcium ammonium nitrate is similar to ammonium nitrate. Soil
microorganisms are primarily responsible for the nitrification (conversion of ammonium to nitrate) of
ammonium in soils which creates acidity. The lime included in the granules balances part of the acidity
released during nitrification so that it does not acidify the soil as quickly as ammonium nitrate does.


Urea-ammonium nitrate solution (UAN) (28-0-0 to 32-0-0)
• produced by dissolving urea and ammonium nitrate (50:50) in water
• colourless liquid
• 28-0-0 can salt out (precipitate out of solution) if the temperature drops below -18°C (0°F)
• a more concentrated solution (32-0-0) is available but it is not often used in Ontario because
of the salting out factor at higher temperatures (~0°C or 32°F)
• similar to urea, it is subject to loss through ammonia volatilization if UAN is applied to the
soil surface
• herbicides and other pesticides are commonly added to UAN for broadcast application on
the soil
• lends itself to sidedress applications

Avoid applying UAN onto crop foliage as severe burning will result. UAN is the most commonly used
liquid fertilizer in Ontario.

Anhydrous ammonia (82-0-0)
• NH3
• colourless, pungent gas at atmospheric pressure
• m anufactured by reacting natural gas with atmospheric N under high pressures and
• handled as a pressurized liquid
• it is used as the base for all manufactured N fertilizers
• s imilar to urea and ammonium nitrate in acidifying effect (1.8 lb CaCO3 to neutralize acidity
generated per lb of N supplied)

Anhydrous ammonia is applied by injecting it into the soil where it vapourizes and dissolves in the soil
moisture. To reduce vapour losses to the air, the anhydrous band must be placed deep enough in the
soil that the injection slot closes over and forms a good seal.

There is some concern that anhydrous ammonia is harmful to soil life. Within the injection band, high
soil pH and hygroscopic conditions are severe enough to kill earthworms and other soil fauna and
microflora but this zone is relatively small and dissipates quickly. The population of soil organisms
quickly recovers and is actually increased by the addition of N to the soil ecosystem.

Ammonium sulphate (21-0-0-24)
• (NH4)SO4
• white to brown solid, industrial by-product obtained by neutralizing ammonia from coke ovens
with recycled sulphuric acid or from nylon manufacturing
• may contain about 0.5% moisture and minute amounts of nutrients such as K, calcium, copper,
iron, manganese and zinc
• generally more expensive per unit of N than urea

Ammonium sulphate breaks down to ammonium and sulphate when dissolved in the soil water. It is
useful for surface broadcast applications as there is less risk of ammonia volatilization. Depending on
the source, its form is granular or coarse powder.


Calcium nitrate (15-0-0)
• Ca(NO3)2
• white solid
• expensive source of N
• used only where both calcium and N are required and soil acidification is undesirable
• contains N in nitrate form and water soluble calcium
• h ighly hygroscopic and may liquefy completely when exposed to air with a relative humidity
above 47%

The highly soluble nitrate-N and calcium are immediately available to the plant.

Potassium nitrate (12-0-44)
• KNO3
• white solid
• e xtracted from dry brine lakes (e.g. Dead Sea) or manufactured by reacting potassium
chloride and nitric acid
• expensive source of N and K
• used mainly for horticultural crops, tobacco and hydroponics

The above content was adapted from the Soil Fertility Handbook, OMAFRA Publication 611,
p. 149-153.

Performance Objective 2
Determine the right source of nitrogen based on:

a. crop type and cropping system;
b. climate (temperature, precipitation, leaching, and runoff patterns);
c. soil texture and the effect of surface soil pH;
d. environmental concerns in the local area (surface and groundwater);
e. crop stage.

Identification of the most appropriate sources of N for a given situation is generally governed by the
method (e.g. fertilizer placement), timing of fertilizer application with respect to seasonal environmental
conditions and crop utilization of the applied N and whether the N fertilizer is blended with other
fertilizer materials or other nutrients are needed. Generally the most commonly used N fertilizers in
field crop production such as urea, UAN, ammonium nitrate, calcium ammonium nitrate and anhydrous
ammonia are less expensive than materials such as ammonium sulphate, calcium nitrate and potassium


Crop Type and Cropping System
Urea can be bulk-spread, either alone or blended with most other fertilizers. It is recommended that
the spreading width not exceed 50 feet when combined with other fertilizer materials. Urea and
fertilizers containing urea can be blended quite readily with monoammonium phosphate (11-52-0) or
diammonium phosphate (18-46-0). However, urea often has a lower density than other fertilizers with
which it is blended. This lack of “weight” produces a shorter “distance-of-throw” when the fertilizer
is applied with spinner-type equipment. In extreme cases, this will result in uneven crop growth and
“wavy” or “streaky” fields. Reduced rates of urea (maximum 10 kg ha-1) can be placed with the
seed of spring oat and barley although it is generally recommended not to apply urea with the seed
of crops such as corn, winter wheat, triticale, barley, canola, etc. Liquid fertilizers containing half as
much N as P2O5 often contain urea and thus seed applications should be avoided in most instances.
Banding of urea in corn also requires a lower application rate (maximum 40 kg N ha-1) compared
to other N sources (maximum 55 kg N ha-1). Using urea in the band also reduces the amount of
potassium that can be applied with the seed or in a band near the seed. If using urea, the fertilizer
bands can be moved farther from the seed row to avoid toxicity although this may reduce the benefit
from other banded nutrients. Urea should not be blended with superphosphates unless applied shortly
after mixing. Urea will react with superphosphates, releasing water molecules and resulting in a damp,
sticky material which is difficult to store and apply. Similarly, mixing urea with potash (KCl) can result in
caking if the material is stored for a long period of time.

Fluid fertilizers can be blended to precisely meet the specific needs of a crop. Solutions of UAN are
very versatile and widely used as a source of plant nutrition. Due to its chemical properties, UAN is
compatible with many other nutrients and agricultural chemicals and is frequently mixed with solutions
containing P, K and other plant nutrients. This may reduce the number of passes required for the crop.

Nitrogen Fertilizer in Storage

Courtesy Fertilizer Canada


Ammonium sulphate is used primarily where there is a need for supplemental N and S to meet the
nutritional needs of the crop. Since it only contains 21% N, there are other fertilizer sources that are
more concentrated and economical to handle and transport. However, it provides an excellent source
of S. Because of the amount of ammonia and salt index, ammonium sulphate fertilizer application in
the seed row can lead to either ammonium or salt toxicity, especially if applied with other fertilizer

Ammonium nitrate is a popular fertilizer since it provides half of the N in the nitrate form and half in
the ammonium form. The nitrate form moves readily with soil water to the roots where it is immediately
available for plant uptake. The ammonium fraction is held on the soil cation exchange capacity
(CEC), taken up by roots or undergoes nitrification to nitrate by soil microorganisms. Many vegetable
growers prefer an immediately available N source for plant nutrition and use ammonium nitrate. It is
also popular for pasture and forages since it is less susceptible to ammonia volatilization losses than
urea-based fertilizers when left on the soil surface. Ammonium nitrate is commonly mixed with other
fertilizers however the mixtures cannot be stored for long periods as they will absorb moisture from the
air and cake. Mixtures with urea result in the formation of a liquid or slurry. There are also concerns
for the detonatability (mixtures with sulphates) or combustion (mixture with elemental sulphur) of certain
blends. The very high solubility of ammonium nitrate makes it well suited for making solutions for
fertigation or foliar sprays.

Anhydrous ammonia is one of the more dangerous chemicals handled on the farm and must be placed
well into the soil and properly covered or the NH3 will volatilize from the soil. Pre-plant and sidedress
applications of anhydrous ammonia for corn production are possible although care must be taken to
ensure the point of injection is far enough from the seed row or developing plant to avoid injury and
ammonia toxicity. This obviously impacts the crop type or cropping system where anhydrous ammonia
can be used.

Given the relative ease at which N can be lost from the soil, it is preferable to apply N as close to the
period of crop uptake as possible. Fall application of N on winter cereals should be limited and the
majority of N should be applied the following spring. Application of UAN through streamer nozzles
causes little to no leaf burn, however considerable leaf burn and yield reductions can occur if UAN is
applied to an emerged crop using flood jet or tee-jet nozzles, especially when combined with contact
herbicides. Nitrogen for spring cereal can be either soil applied and incorporated prior to plant, or
with a top-dressing application especially when some of the fertilizer N has been applied as a starter at

Climate (temperature, precipitation, leaching, and runoff patterns)
Temperature affects processes within the N cycle through its impact on chemical reactions and
microbial activity. In general, when soils are not frozen, higher temperatures speed up the processes or
microbial activity while cooler temperatures slow things down. It should be noted however, that certain
microbial processes (e.g. mineralization, nitrification, etc.) can appear faster in the fall than spring,
even though soil temperatures are the same. This may simply be a reflection of a greater number of
microorganisms in the soil after the growing season compared to after winter.

Surface applied urea N fertilizers, should not be applied during warm humid conditions, or on wet
residues because of the high potential for N losses through ammonia volatilization. Light rainfall or
even heavy dews can provide enough moisture for urea hydrolysis to occur but not enough water
to move the urea into the soil, again resulting in a significant amount of N loss through ammonia


After hydrolysis of urea, the ammonium produced can be readily nitrified even when applied late in the
fall and can be quite susceptible to denitrification or leaching in the fall through to the following spring.
Anhydrous ammonia applied in the fall does not nitrify as quickly due to the stunting of microorganisms
in the anhydrous ammonia application band. However, spring applications would be expected to result
in greater N use by the crop and lower levels of nitrate leaching through the soil.

Nitrate fertilizers are very soluble resulting in a high salt index which influences their rate and
placement with respect to seed row or root system. Since N is already in the nitrate form, it is very
mobile in the soil and more easily lost through leaching.

Due to the soluble nature of most N fertilizers, N is usually moved into the soil with incoming
precipitation before runoff from the soil surface begins. In general, conditions that lessen the amount of
infiltration of incoming precipitation would encourage N losses in runoff if soluble forms of N remain at
the soil surface.

Soil Texture and the Effect of Surface Soil pH
Soil texture impacts the retention and conversion of N in several ways. Typically sandy soils drain
quickly and have a low CEC thus allowing the leaching of ammonium. Nitrification occurs under
aerobic conditions and again this process would be more favorable in coarse-textured soils. Coarse-
textured soils have a lower water holding capacity and therefore a greater potential to lose nitrate
through leaching when compared with fine-textured soils. Some sandy soils, for instance, may retain
only 1/2 inch of water per foot of soil while some silt loam or clay loam soils may retain up to 2 inches
of water per foot.

In finer textured soils, there is usually a higher CEC, thus retention of ammonium and its leaching and
nitrification rates are lower. Because fine-textured soils drain slower and retain more water than coarse-
textured soils, the occurrence of anaerobic conditions is increased, which can give rise to greater losses
of N through denitrification.

As noted under P.O. 1 above, urea converts to the ammonium form of N in the soil. The urease
enzyme (present in soils, bacteria and crop residues) speeds the process. Surface-applied urea is
subject to losses of ammonia. Losses increase with higher soil pH, more crop residues and with higher
temperatures. Avoid urea applications when the fertilizer will remain on the soil surface for prolonged
periods of time. Because clay soils tend to have higher CEC and a greater buffer capacity, they may
retain more ammonium and experience less ammonia volatilization than coarser-textured soils when
urea or other ammonium based fertilizers are surface applied.

Environmental Concerns in the Local Area (Surface and Groundwater)
Since fertilizer N is either applied as, or is quickly converted to, soluble mineral N forms that are
prone to leaching losses, it is extremely important to reduce the amount of residual fertilizer N in the
soil at the end of the growing season. Ontario’s precipitation is relatively uniform throughout the
year, although leaching potential is greatest in the non-growing season due to lower temperatures and
limited plant growth resulting in less evapotranspiration. Applying only enough N fertilizer to meet
crop requirements for a realistic yield goal, time of application and use of slow-release fertilizers are N
management practices that will reduce N leaching.


A variety of coatings can be applied to fertilizer particles to control their solubility in soil. Controlling
the rate of nutrient release can offer environmental, economic and yield benefits. Coatings are
typically applied to granular or prilled N fertilizer but multi-nutrient fertilizers can also be coated. Since
urea has the highest N content of common soluble fertilizers, it is the base material for most coated

Anhydrous ammonia has the highest N content of any commercial fertilizer however handling NH3
requires careful attention to safety. Since it is very water soluble, free NH3 will rapidly react with body
moisture such as lungs and eyes causing severe damage. Accidental escapes of NH3 to the atmosphere
must be avoided. Emissions of NH3 are linked to atmospheric haze and changes in rain water
chemistry. The presence of elevated NH3 concentrations in surface water can be harmful to aquatic

Crop Stage
Urea can be used as a starter, broadcast or top-dress application and can be used in fertilizer mixes
(dry or liquid). Advantages of urea are its high N content (45% to 46%), relatively low cost per lb of
N, and rapid conversion to plant-available N. Disadvantages are lower safe rates of N, or N and
potassium fertilizers that can be applied with or near the seed of many field crops. If the fertilizer is not
being incorporated, other N sources (e.g. UAN, ammonium nitrate, calcium ammonium nitrate) are less
susceptible to ammonium volatilization than urea.

Applying UAN onto crop foliage through streamer nozzles is acceptable although using flood jet or tee-
jet nozzles can result in severe burning.

A solution containing dissolved ammonium sulphate is often added to post-emergence herbicide sprays
to improve their effectiveness at weed control. This increases herbicide efficacy when the water supply
contains significant concentrations of calcium, magnesium or sodium.

Competency Area 2
Determining the Right Rate of Nitrogen

Performance Objective 3
Interpret how soil test nitrogen levels relate to crop yield response
and potential environmental impacts.

Soils can vary greatly in their ability to supply N. Ontario’s soil N test measures the amount of nitrate
in the soil and has only been calibrated for corn and spring barley. Typically most, if not all, of the
nitrate N in the soil from the previous year has been immobilized, leached or denitrified before spring
planting. Therefore, the amount of nitrate found in the soil in the spring arises from the mineralization
of organic N to form ammonium and the nitrification of this ammonium to nitrate. The amount of nitrate
in the soil is believed to reflect the amount of organic N in the soil that will be mineralized during the
growing season and thus available N to the crop. Therefore, the higher the soil test N levels in the
spring, the lower the crop response to and need for fertilizer N.


As noted above, the amount of nitrate in the soil in the spring depends upon the activity of soil
microorganisms and the amount of mineralizable organic N in the soil. Since temperature and
moisture levels can impact microbial activity, the amount of nitrate found in the soil can also vary with
weather conditions. Cool spring conditions will reduce the amount of nitrification in the soil, leading
to an underestimation of the N supplying power of the soil over the growing season. Conversely,
unusually warm springs can lead to greater nitrate formation and an overestimation of the soil N

Other field activities can also cause changes to the nitrate levels of the soil which make the prediction
of the soil’s N supply difficult. Incorporation of readily decomposable organic material with a large
C:N ratio could result in the immobilization of nitrate and lower soil N test levels. Conversely,
application/incorporation of materials with a low C:N ratio (e.g. legume plow down), or a source of
both easily mineralizable organic N and ammonium (e.g. animal manure) could cause an increase in
mineralization and nitrification resulting in elevated nitrate N levels and an over-estimation of the soil N
that will be supplied to the crop during the growing season.

Many of the factors included in the general recommendations will influence the soil nitrate levels,
so the recommendations for the nitrate-N soil test should be viewed as separate from the general N
recommendations. Research is ongoing to find methods to incorporate the soil test into the general
recommendations as an adjustment as well as to account for spring weather conditions.

Sometimes the fertilizer recommendations based on the nitrate-N soil test need to be modified based on
application of N-containing materials after the collection of soil samples. Information will be provided
with the test results on how to make appropriate adjustments.

The nitrate-N soil test has not been adequately evaluated for:
• legumes or manure plowed down in the late summer or fall;
• legumes in a no-till system; and,
• s oil samples taken prior to planting before the soil has warmed up significantly
(i.e. in mid- to late April)

In these circumstances, use the nitrate-N soil test with caution.

Providing that the nitrate-N soil test has adequately predicted the additional fertilizer N requirement of
the crop there should be a lower risk of over fertilizing with N, and thus lower environmental impact
due to N loss from the soil.


Performance Objective 4
Discuss the environmental risk of applying nitrogen above economic optimums.

Crop responses to applied N fertilizer typically follow a concept referred to as the law of diminishing
returns, where each increment of N added results in a successively smaller and smaller yield response
to the applied N until no further yield response is observed as depicted in the figure below. Note,
while corn yield response to applied N will typically level off, smaller grains will likely display yield
reductions with excessive applications of fertilizer N. At some point along this response curve, the cost
of the last increment of fertilizer added results in an equal value of yield response. In other words, the
last dollar of fertilizer gave back a dollar worth of yield. This point is called the economical optimum
rate of fertilizer N application (also known as the most economical rate). After this point, a dollar of
fertilizer gives back less than a dollar in yield. The economical optimum rate of N for a response curve
like the one below can be calculated by finding the point on the curve where the slope equals the price
ratio (PR), as calculated by the equation: PR = $/kg fertilizer N

$/kg crop

For most Ontario crops, the economical optimum rate of N fertilization often occurs at ~ 90%-95% of
the maximum yield, depending upon the shape of the response curve and the PR.

The amount of applied N fertilizer that enters the crop, follows a pattern similar to the diminishing
returns in that at some level of fertilization, the additional increments of N fertilizer applied, above
that level, result in less N entering the crop. One way to assess how well a crop is utilizing applied
N fertilizer is to assess its N recovery efficiency (NRE). The NRE can be viewed as simply the amount
of applied fertilizer N found in the harvested crop divided by the amount of N applied (see equation
NRE = (Amount of N in crop with fertilizer)-(Amount of N in crop without fertilizer)
Amount of fertilizer N added

Generally speaking, NRE are usually
around 40%-60%, depending on
several factors such as source, timing
and rate of N application. Fertilizer
N applications above the economical
optimum rate would be expected to
have a lower NRE value, and thus a
greater amount of residual fertilizer N
remaining in the soil after crop harvest.
Studies have demonstrated that post-
harvest residual nitrate levels increase
greatly when application rates exceed
the amount required for optimum
economic yield. The amount of this
residual mineral N left in the soil after
crop harvest is also a reliable indicator
of the risk of loss through either leaching
or denitrification.

Graph Source: Ivan O’Halloran, Ridgetown Campus, University of Guelph


Under certain weather conditions, N can be lost from the soil between application and crop uptake
especially in regions with moderate to high rainfall. Using the correct amount of N optimizes crop
yield while minimizing loss of N to the environment.

Using excessive rates reduces profitability for the farmer and can result in excess nitrate being delivered
to ground and surface water resources, or increases in denitrification and greenhouse gas production.

Performance Objective 5
Justify the considerations for nitrogen application rate based on:

a. economics;
b. weather and climate, including;

i. temperature;
ii. precipitation amount;
iii. rainfall intensity;
iv. precipitation patterns;
c. crop type and growth stage.

Ideally, fertilizer N application based on the economically optimum rate of N would be the most
profitable for the farmer. Based on the PR as described in the previous P.O., one would consider
reducing the rate of fertilizer N applied as PR increases (i.e. as fertilizer cost per unit of N increases
or as the crop value decreases). Conversely, as the PR decreases the economical rate of N would
increase. The difficulty with this approach is that one must use past yield responses to serve as a
predictor of the current year’s crop response to N fertilization. This can lead to inaccurate predictions
of the economical rate of N as crop responses to fertilizer N can vary with factors such as growing
season conditions, N source, method of application and crop variety. Research studies suggest that
variations typically observed in the year to year values of the PR would have much less impact on the
rate of fertilizer N that should be applied compared to the changes in the economical rate of N based
on differences in the crop response to fertilization from one year to the next. While this is an obvious
limitation of this approach for making fertilizer recommendations, alternative approaches such as those
based on yield goal are similarly impacted by the same factors.

Weather and Climate
Nitrogen fertilizer can be lost from agricultural fields especially in regions with moderate to high
rainfall. The risk of N loss will depend to some extent on the form of N applied and conditions after
fertilizer application. Ultimately, the longer the applied fertilizer remains in the soil, the more likely it
will be converted to nitrate and thus prone to leaching or denitrification losses if rainfall amounts or
intensity result in water movement through the soil.


The first period with a high risk of N loss is spring, when soils tend to be wet and before rapid crop
growth begins to pull water out of the soil. This risk ends sooner with crops that begin rapid growth
early in the spring, such as wheat and grass. Early spring application of N for summer crops, like
corn, can result in loss of N and reduction in yield. One usually sees higher N application rates
recommended for pre-plant applications due to these losses. If N is to be applied more than two weeks
before planting, use of anhydrous ammonia is recommended as this may delay nitrification and reduce
risk of nitrate leaching and yield reductions.

A second period of high risk for N loss can occur in late May and June. Urea hydrolysis and
nitrification will have converted a significant amount of applied fertilizer N to nitrate. Even though
rapid crop growth may have started, if heavy rains create saturated or near-saturated soil conditions
for several days or longer, the combination of warm and wet soil conditions can lead to rapid N
loss through leaching and denitrification. The denitrification risk is greatest on poorly drained soils.
Sidedress application of N or use of N stabilizers with pre-plant applications may reduce the risk of
these losses.

The third period of high risk for fertilizer N loss is after the growing season when residual fertilizer N
remains in the soil. Application rates above the economical optimum rate typically result in greater
residual levels of fertilizer N in the soil and thus greater N losses. If one consistently has high residual
soil N levels after crop harvest, reduction of future fertilizer rates is warranted.

Crop Type and Growth Stage
In all crops, rapid uptake of N occurs during the maximum growth period. There is not much risk of
N loss when fertilizer is applied at the beginning of the period of rapid growth as this is usually when
soils are drier. Nitrogen application should be timed to provide adequate amounts of N when plants
are actively growing and using N rapidly. Losses of applied N from fertilizer can be reduced by
delaying application until the crop has emerged (side dressing). Split N applications, where some N is
applied prior to crop emergence and the balance after emergence, can increase crop N-use efficiency
and generally lower fertilizer N requirements on medium and fine-textured soils. While multiple N
splits/application would in theory improve N use efficiency, no consistent benefit has been shown for
many field crops, and additional application costs must be considered for the increased number of
field passes.

Because the Rhizobia bacteria that infect legume roots normally supply adequate N to the host plant,
well-nodulated legumes rarely respond to additions of N fertilizer. Occasionally, however, soybeans
may respond to applications of N late in the season, presumably because N fixation in the nodules
has declined significantly. Such responses are quite erratic though, and late-season applications of N
to soybeans are not routinely recommended. The amount of atmospheric N fixed by non-symbiotic soil
organisms varies with soil types, organic matter present and soil pH.

Planting cover crops after harvest in the fall or between crops will capture or recover a portion of the
residual N in the soil after main crop harvest and potentially help prevent N loss.


Performance Objective 6
Justify the considerations for nitrogen application rate based on:

a. soil characteristics including leaching;
b. topography and runoff;
c. crop conditions, including crop type and growth stage.

Soil Characteristics
Losses of N from the soil generally occur with the mineral forms of N (i.e. ammonium or nitrate).
Leaching losses tend to be greater for coarser textured soils, while denitrification losses are greater for
poorly drained and heavier textured soils. Compared to a silt loam soil, Ontario’s corn N calculator
would generally increase N application rates on finer textured soils (clays, heavy clays, clay loams, silty
clays and silty clay loams) and coarser textured soils (loam, loamy sand, sandy loam and sandy clay).

In southwestern and central Ontario, soil texture also affects the rate of fertilizer N recommended as a
sidedress application on corn. For sand and loamy sand soils, the rate of N recommended as a
pre-plant or sidedress remains the same. For other soil textures, sidedress N rates are decreased by
10% (sandy clay, sandy clay loam and sandy loam) or 20% (clay, clay loam, loam, silt loam, silty clay
and silty clay loam).

Although the vast majority of soil N is in the organic N form, and one might expect greater soil N
supply from soils with higher organic matter content, there is no specific recommendation for changing
N rates based on soil organic matter. This may reflect the fact that the range of soil organic matter
encountered in most field crop situations is insufficient to significantly impact the amount of soil N
actually supplied to the crop. Improved soil conditions due to higher soil organic matter content
improves conditions for crop growth thereby increasing crop N requirement which negates the
additional N supplied from the soil.

Topography and Runoff
Given that the soil’s supply of N to the crop comes almost entirely from the organic N pool, locations
within a field with higher soil organic matter will likely provide more N to the crop. In most fields
where there are substantial changes in topography, soil organic matter content increases as one moves
down slope, reflecting the impact that water redistribution in the landscape has had on plant growth.
While upper slope positions have less soil N, those soils also tend to be shallower, with lower water
holding capacity and drier. Thus, water typically becomes the limiting factor for crop yields and
would predictably reduce the crop’s fertilizer nitrogen requirement under rain-fed conditions. Seasonal
variations in rainfall amount and timing play an important role in determining variations in crop
fertilizer N requirements with slope position. In irrigated systems, increased N application rates may
be justifiable on upper slope positions.


Since most N fertilizers are readily soluble, overland flow and N runoff is unlikely to be a significant
issue as the N will likely be moved into the soil before runoff begins. If runoff is such that erosion has
occurred, then any fertilizer N within the soil will have moved with the soil as well. Eroded areas are
typically lower in soil organic matter, suggesting a greater need for additional N fertilizer. However,
soil conditions (poor structure, water holding capacity, etc.) are usually what limit crop growth and thus
additional fertilizer N is not warranted until the erosion problem has been addressed.

Crop Conditions
See also P.O. 5 above.

For many crops, cumulative N demand usually follows an S-shaped curve, with a slow uptake rate
during establishment and an exponential utilization in the vegetative and reproductive phases. Splitting
N application is thus recommended by applying N in phase with crop demand, providing high
soil-N concentrations at different periods needed for crop growth while minimizing the time for risk of
leaching and denitrification losses. This is why one usually sees a lower N recommendation for planter
and sidedress-applied corn versus pre-plant N applications. While it is expected that the amount of
N required should be lower when using spilt applications, this has not always been observed when
making multiple N applications throughout the growing season.

Crop colour appears to be the most reliable indicator of N stress for a range of crops during the
growing season. Lighter colour indicates more N stress and a need for additional N. While repeated
observations of N stress year in and year out would be indicative of a need for increased N rates,
sporadic occurrences of N deficiency must be placed in the context of the growing season conditions,
timing and severity of the stress, and the potential economic gain versus treatment cost if N was to
be applied in-season. This approach only works for fertilizer applications made during the growing
season. Most producers make in-season applications of N to wheat and forage grasses. Soybeans
may also display pale green colour as seed reserves of N are depleted and nodulation is not yet fully
developed. Application of N fertilizer will alleviate the N stress symptoms but is unlikely to impact yield
and thus is a waste of resources. Sensors can be mounted either on tractor-based or high-clearance
sidedressing equipment and can control application rates of sidedress N. However, numerous other
stresses can cause differences in crop colour and chlorophyll content. Some corn varieties may
respond to later in-season N applications although the full impact of such applications on total crop
fertilizer N requirement, crop yields, crop N uptake and residual soil N is still under investigation.

Imbalanced plant nutrition, and particularly an excess of N, can lead to lush growth which is softer and
is less able to withstand disease. Excess N can also lead to dense plant canopies which trap humidity
within the canopy and create conditions where many fungal diseases can thrive.


Performance Objective 7
Calculate nitrogen credits from:

a. previous nitrogen application;
b. soil organic matter;
c. manure;
d. biosolids and other organic amendments;
e. irrigation applications (groundwater and wastewater);
f. previous legumes.

Previous Nitrogen Application
In the context of fertilizer N applications, one would consider the full amount of fertilizer N applied for
the current crop to be credited towards the crop being planted. In general, issues regarding previous
fertilizer N applications are likely limited to replant situations (as limited carry over of fertilizer N from
one season to another is expected) or accounting for N applied either pre-plant or with the planter
when sidedressing or top-dressing. Organic sources of N, such as manures, will provide a source of N
in subsequent years as well. Based on the amount of manure organic N applied, an N credit would be
calculated as 10% in the second year, 5% in the third year, and 2% in the fourth year. For example,
for every 100 kg ha-1 of organic N applied in manure in 2016, we would calculate a residual manure
N credit of 10 kg ha-1 in 2017, 5 kg ha-1 in 2018 and 2 kg ha-1 in 2019. The N credit for manure in
year of application is discussed in the section pertaining to manure in this PO.

Compost Application.

Courtesy Christine Brown


Soil Organic Matter
While soil organic matter is the dominate pool of N in soil, the mineralization of this N to a plant
available form can be affected by numerous factors. As such, there is no N credit given based strictly
on soil organic matter content. Base N requirements for soil texture in different regions of the province
are provided in Table 2.1. The table indicates a smaller influence of texture on corn N requirements in
Eastern Ontario compared to other corn producing areas in the province.

Table 2.1. Soil Texture and Base N Requirements for Corn

Base N Requirement

Soil Texture Metric Imperial

Southwestern and Eastern Ontario* Southwestern and Eastern Ontario*
Central Ontario Central Ontario

Clay, heavy clay 53 1 47 1

Clay loam 40 1 36 1

Loam 32 1 28 1

Loamy sand 46 19 41 17

Sandy loam 38 19 34 17

Sand 52 19 46 17

Sandy clay, sandy 43 19 38 17
clay loam

Silt loam 20 1 18 1

Silty clay loam 36 1 32 1

Silty clay 49 1 44 1

*Eastern Ontario includes Frontenac, Renfrew and counties to the East of them.

Chart source: Agronomy Guide for Field Crops, Publication 811, 2009, p.21 and 258.

The best way of determining the amount of N from manure is to analyze a sample. Alternately,
average values will provide an estimate of the nutrients available to the crop. Refer to the chart
contained in Performance Objective 9, Proficiency Area 5, Manure Management.

The availability of manure N to the crop depends on the proportion of ammonium and organic N
in the manure, as well as the timing of application and incorporation. The ammonium N in manure
is chemically the same form of N as in many mineral fertilizers and is immediately available to the
crop. Unfortunately, the ammonium form is also subject to loss by volatilization if not incorporated
immediately. The balance of the N in manure is in the organic form, which becomes available to crops
gradually through the process of mineralization as the organic compounds break down.

More precise estimates of available nutrients can be made by accounting for the actual timing and
conditions for manure application, and the lag time before incorporation. Refer to the worksheet,
Calculating Available Nutrients from Spring-Applied Manure Using a Manure Analysis, contained in
Performance Objective 9, Proficiency Area 5, Manure Management.

As mentioned previously, organic N contained in manures can continue to supply N to a crop for
several years after application


Biosolids and Other Organic Amendments
Since biosolids encompass a wide range of materials, their nutrient contents are also quite variable
and, thus, it is essential (and required by law) that the nutrient content of these materials is known
prior to application (see table below). As with manures, there are mineral and organic N forms in the
biosolids that affect both the immediate and long-term N credit from these materials. Liquid biosolids
from aerobic digesters or from lime stabilized biosolids tend to have lower available N levels (primarily
due to lower ammonium N contents) than anaerobically digested materials. Dewatered biosolids
would have a higher proportion of organic N as most mineral forms of N would be removed with
the water. In general, one considers the mineral and organic forms of N in the biosolids to behave
similarly to those found in manures.

Table 2.2. Ammonium Content of Various Biosolids

Type Ammonium

Municipal Biosolids

Aerobic sewage biosolids 1.6%

Anaerobic sewage biosolids 35%

Dewatered sewage biosolids 12%

Lime Stabilized sewage biosolids trace

Paper Mill biosolids trace

Spent Mushroom compost 5

1. Ammonium content increases as liquid concentration increases.
2. Balance of nitrogen is in organic form.

Source: NMAN Software

Irrigation Application (groundwater and wastewater)
This will require a water test to determine the level of N (usually nitrate-N) and application rates
over the season in terms of acre inches of water applied. Typically, nutrients in water samples are
measured in units of ppm. To calculate the amount of N applied, one needs to know the concentration
of N in the water and the amount of water applied.

An acre-foot of water is 2,719,518 lbs., so for every foot of irrigation water one is adding
approximately 2.72 x ppm of nutrient, or ~0.227 x ppm for every inch of irrigation water applied.

For example, if irrigation water contains 10 ppm NO3-N, then each foot of water applied would give
~27.2 lbs. ac-1 of N, or each inch of irrigation water supplies ~2.27 lbs. ac-1.

For metric units, each cm ha-1 of water weighs 100,000 kg, so 0.1 x ppm of nutrient is the kg ha-1 of
nutrient applied. Using the above example, 1 cm of irrigation water with 10 ppm NO3-N would supply
1 x 0.1 x 10 = 1.0 kg ha-1 NO3-N.

If the irrigation water contains significant quantities of NH4-N, a similar calculation can be performed.

Provincial recommendations currently do not consider an N credit based on N content in irrigation


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