4R Nutrient Management Study Guide

Table 4.2. Liquid Fertilizers

Analyses Weight/ Weight/ Weight/ Imp. gal/ US gal/ Litre/
US gal (lb) Imp. gal (lb) litre (lb) tonne tonne tonne

8-25-3 11.11 13.35 2.94 165.1 198.4 749.9

6-18-6 10.69 12.85 2.83 171.6 206.2 779.0

3-11-11 10.45 12.55 2.76 175.7 211.0 798.8

9-9-9 10.49 12.60 2.77 175.0 210.2 795.9

7-7-7 10.41 12.5 2.75 176.4 211.8 801.7

6-24-6 11.07 13.30 2.93 165.8 199.2 752.4

9-18-9 11.07 13.30 2.92 165.8 199.2 755

5-10-15 10.7 12.85 2.83 171.6 206.0 799

2-10-15 10.62 12.75 2.81 172.9 207.6 784.6

10-34-0 11.6 14.0 3.09 157.0 188.5 715.8

UAN 10.65 12.8 2.82 172.2 207.0 781.8
(28% to 32%)

Aqua ammonia 7.49 9 1.98 245 294.3 1113.4
20-0-0

54% phos. acid 13.15 15.8 3.48 139.5 167.7 633.5

1 Imperial gallon = 1.201 US gallons 1 US gallon = 0.8326 Imperial gallons
1 US gallon = 3.785 litres 1 Imperial gallon = 4.546 litres

Source: Adapted from Table 7-2 Blended liquid fertilizers, Soil Fertility Handbook, Publication 611, OMAFRA, 2006, p. 156.

Potassium (K) sources

Muriate of potash (0-0-60 or 0-0-62)

• KCl potassium

chloride

• most common

and least expensive

source of K

• c ontains chlorine

(47%), an

essential plant

nutrient needed

for cell division,

photosynthesis

and disease

suppression, in the

chloride form

• a small amount

(less than 100

grams per tonne)

of an amine/oil Muriate of Potash (red). Courtesy Fertilizer Canada

anti-caking agent is often included in the shipped product

• the availability of the K to plants is equal from red and white forms.

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 101

Red muriate of potash (0-0-60)
• mined primarily in Saskatchewan and some in New Brunswick
• c ontains about 97% potassium chloride (KCl), balance is mostly iron impurities which are
responsible for the colour


White muriate of potash (0-0-62)

• obtained by crystallizing potassium chloride out of the mining liquor solution
• almost pure potassium chloride

Potassium sulphate (0-0-50)
• K2SO4
• extracted from the brines of Great Salt Lake in Utah
• a lso contains 17% sulphur in the water soluble form

Potassium sulphate, or sulphate of potash, has a lower salt index and is more expensive than muriate of
potash. It is used mainly on crops sensitive to chloride, such as tobacco, potatoes, tree fruits and some
vegetables, or where sulphur is required for the crop.

Sulphate of potash-magnesia (0-0-22)
• potassium-magnesium sulphate K2SO4•2MgSO4
• mined from deposits in New Mexico
• commonly referred to as K-Mag (brand name of Mosiac Fertilizers’ product) and Sul-Po-Mag

Potassium-magnesium sulphate, or sulphate of potash-magnesia, has a higher cost per unit of K than the
muriate form. It also contains 11% magnesium and 22% sulphur in water soluble form and therefore
readily available to plants. It is useful as a source of soluble magnesium in fields where lime is not
required.

Potassium nitrate (12-0-44)
• KNO3
• produced commercially by reacting sodium nitrate with potassium chloride
• h igher cost per unit of K than other sources, so generally used only for specialty fertilizers
where soluble forms of both K and N are required

Livestock manure
• K concentration in manure varies widely, typically ranges from 2.5% to 4.5% of dry matter,
depending on livestock species and storage system
• Most of the K in manure is soluble and plant available

102 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Secondary Macronutrients
Secondary nutrients are needed occasionally in Ontario soils. If required, they may be applied as part
of a fertilizer blend or added as part of a lime application to correct soil acidity.

The secondary macronutrients include: magnesium, calcium, and sulphur. As indicated in Table
4.3, these nutrients can also be supplied in some of the commonly available fertilizer materials. For
example, sulphate of potash magnesia contains both magnesium and sulphur. Sulphate of potash
contains sulphur as well. Calcium ammonium nitrate can contain small amounts of magnesium along
with calcium. Calcium nitrate is an excellent source of N for speciality crops and contains soluble
calcium. Gypsum (calcium sulphate) provides both calcium and sulphur.

The requirements for calcium and magnesium are most often associated with acidic soil conditions and
the need to correct for proper pH. The two main products used are calcitic or dolomitic limestone.

Calcium
Limestone (either calcitic or dolomitic) is the most common source of calcium. It also increases the pH
of acidic soils. To be effective, it must be finely ground and thoroughly incorporated into the root zone.
Limestone is available in powder form or in pellets made from finely ground limestone. The solubility of
limestone drops quickly as soil pH increases.

In soils with neutral or alkaline pH, gypsum (calcium sulfate) is the preferred form of calcium because it
is more soluble than lime. Gypsum has no effect on soil pH.

Calcium chloride and calcium nitrate are occasionally used as foliar or soil applied sources of calcium.
However, Ca is not translocated within the plant, so foliar application is only effective for deficiencies
in parts of the plant the spray can reach.

Magnesium
Magnesium deficiency is most common in acidic soils. If dolomitic limestone is added to correct the
acidity, it will also supply enough magnesium to correct the deficiency. The solubility of dolomitic
limestone decreases as the soil pH increases, thus it is not effective when applied to alkaline soils. In
neutral or alkaline soils, Epsom salts (magnesium sulphate) or sulphate of potash magnesia can be used
for supplemental magnesium.

Sulphur
Sulphate sulphur is present in a number of common fertilizer materials and can be included in a
fertilizer blend. Most common are ammonium sulphate, potassium sulphate, and sulphate of potash
magnesia. Gypsum (calcium sulphate) can also be used as a sulphur source. Product availability,
transportation costs and crop requirements for other nutrients will dictate which source of sulphur is most
economical.

Granular elemental sulphur (90% S) can be another source. It will also acidify the soil. The sulphur
must be oxidized to sulphate before it is available to the crop, which can take several months. Some of
the intermediate products in the oxidation process can be toxic to crops; therefore, high rates should
be broadcast rather than banded. Broadcasting increases soil contact and hastens conversion to the
sulphate form. After the initial year of application, the pool of plant available sulphate S will most
likely increase.

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 103

Micronutrients

The main micronutrients of concern to Ontario agriculture are zinc, manganese and boron. On
occasion, copper and molybdenum may be required. There are many forms of commercially available
micronutrient products (almost too many to mention), so the choice of product will depend on price,
solubility of the nutrient, and suitability of the product for available application systems. Table 4.3 lists
some of the common materials available.

Table 4.3. Common Secondary and Micronutrient Sources

Nutrient Source % Other Application
Nutrients
Calcium (Ca) calcitic limestone Nutrient Soil Foliar
dolomitic limestone 6%–13% Mg
Magnesium (Mg) gypsum (CaSO4) 22%–40% 23% S *
Sulphur (S) calcium chloride (CaCl2) 16%–22% 64% Cl *
Boron (B) calcium nitrate (Ca(NO3)2) 15.5% N *
Copper (Cu) pelletized lime 29% **
cement kiln dust 36% 2%–9% K2O **
19% 16%–22% Ca *
dolomitic limestone *
26%–32% 13% S
Epsom salts (MgSO4) sulphate of potash 22% K2O; 20% S *
magnesia 6%–13% **
9% 34% N *
ammonium sulphate 11% 50% K2O
potassium sulphate 22% K2O; 11% Mg *
sulphate of potash magnesia 24% 29% Ca *
calcium sulphate 18% *
granular sulphur 22% *
23% *
various granular materials 90%
Solubor™ *
12%–15% *
copper sulphate 20%
copper chelates *
25%
Manganese (Mn) manganese sulphate manganese chelates 5%–13% *
*
Molybdenum (Mo) sodium molybdate 28%–32%
5%–12% *
Zinc (Zn) zinc sulphate
zinc oxysulphate 39% **
zinc chelates *
36%
8%–36% *
9%–14%

Source: Soil Fertility Handbook, Publication 611, OMAFRA, 2006, p. 158.

Granular micronutrients
These products are blended with other fertilizer ingredients for broadcast application or used as a
starter fertilizer. Compatibility with the other ingredients is important, both chemically and in granule
size. Since certain micronutrients are toxic to plants if over-applied, segregation of the fertilizer blends
must be avoided.

104 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Oxy-sulphates
• combinations of the oxide and sulphate forms of the micronutrient
• sulphates much more soluble and available than the oxides
• oxides much more stable in a blended product
• oxides only slowly available to the crop

These products have been declining in popularity because of the inconsistency in plant availability and
crop response.

DDP- Dry Dispersible Powders
These are finely ground oxy-sulphate materials that are intended to be added to dry blended fertilizer.
The static charge causes these nutrients to cling to each and every granule in the blend with the idea
that micronutrients are better distributed throughout the blend and subsequent application enhancing
nutrient uptake.

Sulphates
• more soluble than oxides
• tend to be hygroscopic and can cause problems with caking or clumping when mixed with
other fertilizer ingredients. This can be managed by applying the fertilizer soon after blending.

Despite these concerns, their consistent plant availability has made them popular in fertilizer blends.

Liquid and soluble micronutrients
These materials may be mixed with water and sprayed on crop foliage or mixed with liquid fertilizers.

Chelates
• c omplex organic molecules that bind metallic ions, protecting them from reactions with other
minerals to form insoluble compounds
• allows many of these nutrients to be mixed with liquid fertilizers without forming insoluble
precipitates
• may increase the availability of the nutrients in soil
• most commonly used chelating agents are EDTA and DTPA
• o ther organic materials (humic acids, lignosulphonates, glucoheptonates) will form complexes
with metallic ions but do not hold them as tightly as a true chelate

Chelates are considerably more expensive than other soluble forms of micronutrients. They should be
used with care, since they can complex minerals already in the soil and make the deficiency worse.

Soluble powders
• least expensive form of micronutrients for foliar application and the most consistently reliable
• most require a sprayer with good agitation to keep material in solution
• sticker-spreader needed to get the nutrient through the cuticle and into the leaf.

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 105

Performance Objective 2
Discuss considerations that may be used to determine the right source of
potassium, secondary macronutrients, and micronutrients based on:

a. crop type;
b. cropping system;
c. crop growth stage;
d. soil test or tissue test;
e. timing of application.

Choosing the Right Source of Potassium based on Crop Type
The four main product choices are muriate of potash, sulphate of potash, sulphate of potash magnesia,
and potassium nitrate. All the potassium sources are essentially equal in K availability, so the choices
come down to crop safety for particular application methods (that may vary with crop species), other
nutrients in the fertilizer with the K, and absence of Cl for specific sensitive crops (e.g. tobacco,
raspberries).

Muriate of Potash (MOP)
Muriate of potash is used on a broad range of crops
and is by far the most common choice. It is readily
soluble and plant available. It does contain chloride
which can add to the salt index and cause crop
damage early in the season if placed too close to the
seed and at high rates. Similar considerations apply
when contemplating its use on soybeans and wheat
and during the establishment year of forages.

Sulphate of Potash Magnesia (SPM) Red Muriate of Potash. Courtesy Fertilizer Canada
This may be a good choice if the soil pH is in the
proper range and there is a clear need for both
supplemental sulphur and magnesium.

Sulphate of Potash (SOP)
This product is considered a low salt index product. If there is a need for sulphur and no other sources
of sulphur are coming from other materials then this may be a good choice. However, it is the most
expensive form of potassium. Another consideration is for crops sensitive to chloride such as tobacco.
Then, muriate of potash has limited application and SOP is substituted for part of the potassium
requirement.

Potassium Nitrate
This product is soluble enough to be fertigated throughout the season and provide supplement N and
K at critical crop developmental stages. It may be an appropriate choice in vegetable production or
where drip irrigation is implemented.

106 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Livestock Manure
Manure is an excellent source of potassium. Potassium content varies by livestock class. A manure
lab test or use of book values will be necessary to assess nutrient content and determine rates of
application. The K content of manure is highly available in the year of application, it is estimated to
be 90%. Manure also contains other nutrients and therefore consideration of other nutrients contained
in the manure such as nitrogen and phosphorus may limit the application rate. Various crops in the
rotation may have a high demand for K but a low demand for nitrogen thereby limiting application
rates. Soils test may be high in P and require no further supplementation of P which may limit manure
as a viable source to supply all the required K. Manure is also a good source of micronutrients. Soils
that receive regular manure applications are seldom deficient in micronutrients.

Choosing the Right Source of Potassium based on the Cropping System
The cropping systems in Ontario are varied. Corn, soybean and wheat rotations both in conventional
till and no-till are common cash crop scenarios. Forages, small grains, silage corn and pastures are
common amongst livestock producers. Vegetable and specialty crops is another distinct system.

The choice of product depends on the need for supplemental potassium. Muriate of potash is the most
flexible and economical in a number of cropping rotations. It can be fall or spring applied, banded
(within limits), broadcast or blended with other fertilizers.

Manures may be a viable option if soil tests for P and K indicate that they are required and nitrogen
recommendations are not exceeded by the determined application rate.

Crop rotations that include forages and corn silage with high crop nutrient removal are likely the acres
to benefit the most from manure applications.

If tobacco is in the rotation, reducing the use of MOP and increasing the use of SOP or SPM will
improve quality.

Choosing the Right Source of Potassium based on the Crop Growth Stage
In most crop rotations, it is the vegetative growth stage that requires the most potassium. Applying
the potassium ahead of time to the soil will insure adequate supply for root uptake. Depending on a
foliar application to provide sufficient K is not a good strategy. None of the potassium products can be
applied safely and with sufficient quantity to meet the crop demands without causing crop damage.

On soils testing low in K, placing a small amount of K in a starter band on corn has shown significant
yield advantage over broadcast K only.

Applying manure in crop has drawbacks both in terms of specialized equipment and practicality of
performing the task. Therefore, early pre-plant spring applications that capture most of the available N
can be a significant source to supply nitrogen, phosphorus and potassium. Fall applied manure results
in lower N availability for the following year but can be a significant source of K to the following crops
along with P and micronutrients.

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 107

Choosing the Right Source of Potassium based on the Soil Test or Tissue K
Soil testing should always be used to determine the need for supplemental potassium. However, the soil
test does not specify the source of K to use. The source should be based on availability of supply, crop
quality needs and economics. In most cases, MOP can be used. With some speciality crops such as
tobacco a mix of MOP, SOP and sulphate of potash magnesia may be required to reduce the chloride
content and/or supply magnesium or sulphur. If high rates of K (>200 kg K2O/ha, or >250 kg N +
K2O/ha) are required for spring application on sand soils, SOP may provide greater crop safety, either
on its own or as a replacement for part of the MOP.

Manure that is either fall or spring applied can offer significant amounts of N, P and K. Manure is a
bundle of nutrients therefore the application rate should be considered relative to the particular nutrient
needs of the crop and the nutrient content of the manure. This approach will avoid over application of
nutrients and offer greater insight in perhaps using manure more effectively in lower testing soils that
require more P and K.

Plant tissue K will indicate whether the plant K content is above or below a critical level. If the test is
below the critical level, then crop growth and yield may be reduced by the lower K concentration.
Seldom is it economical to apply foliar K. There may be an opportunity, if caught early enough, to
supply supplemental K to the soil, however, this is rarely practical. Usually, low K is symptomatic of
something else limiting K uptake such as dry soil or soil compaction limiting root growth and diffusion
rates or surface stratification of K due to shallow incorporation.

Choosing the Right Source of Potassium based on the Timing of Application
The timing of K application takes into account crop needs, application equipment options and tillage
practices. In the 4R stewardship approach, all the Rs are interconnected. It is difficult to talk about
source without including timing, rate and place.

MOP is flexible in so far as it can be banded, broadcast and incorporated in fall or spring. The
most important part is to soil test to determine the need, crop quality considerations and apply the
appropriate amount to optimize crop performance. K has limited mobility and therefore requires the
K to be applied ahead of crop needs and incorporated into the root zone by tillage or equipment that
can place it in the root zone.

Small amounts placed in a band as a starter in low K test soils has proven to be a viable option for
applying some of the K at planting time. The balance can be broadcast and incorporated in either the
fall or spring on the appropriate soil texture.

108 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Choosing Sources of Secondary and Micronutrients
Magnesium
The first consideration is to determine the soil pH. If lime is required, the choice of dolomitic limestone
will provide a source of magnesium. If pH adjustments are not needed, then a product such as sulphate
of potash magnesia would be a choice especially if sulphur and potash are also required. If it is
determined that only magnesium is required, there are numerous sources of magnesium sulphate or
magnesium oxy sulphate from which to choose.

Calcium
The choice of calcium follows the same logic as dolomitic limestone. If pH adjustments are needed and
magnesium levels are greater than 100 ppm, then choose either calcitic or dolomitic limestone. It is
rare for a soil to have inadequate calcium if the pH is in the agronomic range. If supplemental calcium
is needed, choose products such as gypsum if sulphur is also required or calcium nitrate if it is also
appropriate to add nitrogen.

Sulphur
The plant available form of sulphur is sulphate. For in-season applications, it is important to choose
products that contain sulphate sulphur. There are numerous products as previously mentioned. If
nitrogen is also required, ammonium sulphate is a good source. Use of elemental sulphur requires it to
be converted to sulphate forms by soil bacteria. As such, it is not considered a readily available form of
sulphur for plants until it converts to sulphate form which could take weeks to several months to convert.
Farms with a history of manure applications may have sufficient levels of plant available sulphate
sulphur.

Zinc
The most plant available forms of dry zinc are those that contain a significant portion of sulphate.
The least available are zinc oxides. Farms with a history of manure may also have elevated levels of
micronutrients, the organic chelates in manure as well as significant levels of zinc contained in most
manure will maintain soil test levels.

Manganese
As with zinc, the most plant available forms of dry manganese are those that contain a significant
portion of sulphate. The least available are manganese oxides. Soil applications are best done in
banded starter fertilizers rather than broadcast. However, soil applied manganese is the least effective
way to supply manganese. Foliar applications will give more consistent responses for correcting Mn
deficiency because they avoid soil reactions that reduce availability.

Boron
Numerous boron formulations in both dry and liquid are commercially available. Boron can be toxic to
plants if over applied, care is required not to exceed recommended rates.

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 109

Choosing the Right Source of Calcium, Magnesium and Sulphur based on the Crop Type
With few exceptions, the choice of products for calcium and magnesium is done by determining the
need for limestone applications using pH and BpH determinations. Most of our agronomically important
crops require soil pH near neutral or slightly below for optimum performance. An exception is potatoes
which, due to disease control reasons, prefer lower pH for scab control but may require higher calcium
levels for quality. Gypsum is an option here to supply calcium but not influence soil pH.

Sulphur needs are increasing because environmental regulations have reduced industrial sulphur
emissions, and therefore reduced wet deposition on agricultural areas. Winter wheat, canola and
alfalfa are three crops that are most likely to respond to supplemental sulphur, although responses have
not been consistent. The most appropriate sources of sulphur, for the current year’s growth, are those
that provide sulphate sulphur. Elemental S may be utilized for longer-term applications. After the initial
year of elemental S application the pool of plant available sulphate in the soil will most likely increase.

Choosing the Right Source of Calcium, Magnesium and Sulphur based on the Cropping System
In a crop rotation, the choice of calcium and magnesium is often dependent upon the soil pH. It is the
most sensitive crop in the rotation that determines the pH required for optimum growth and therefore the
need for limestone. The choice of calcitic or dolomitic is based on the need for magnesium.

If the pH is in the correct range, then the need for supplemental magnesium, calcium or sulphur
would require the use of products other than limestone. Products such as sulphate of potash magnesia
would be a choice especially if sulphur and potassium are also required. If it is determined that only
magnesium is required, there are numerous sources of magnesium sulphate or magnesium oxy-sulphate
materials to choose from. If calcium is required, then gypsum is an obvious choice.

Crops in the rotation, mainly wheat or alfalfa, will dictate the need for plant available sulphate sulphur.
Choosing products that only supply sulphate is difficult. Choose products that supply other nutrients that
are also required. For example, ammonium sulphate supplies both plant available sulphur and nitrogen,
and so is appropriate for application on wheat, but potassium sulphate may be more appropriate for
application on alfalfa. Blending products (e.g. ammonium sulphate and urea) can provide the needed
nutrients at appropriate rates for the lowest cost.

Choosing the Right Source of Calcium Magnesium and Sulphur based on the Crop Growth Stage
Calcium, magnesium and sulphur are taken up all season long by most crops. An adequate soil supply
is required. To assure an adequate supply requires adjusting soil pH with either calcitic or dolomitic
limestone the year ahead to give time for reactions to occur. If pH is adequate and soil tests indicate
need for supplemental sulphur magnesium or calcium, then applying the most soluble sources ahead
of planting and incorporating into the root zone is a good option. Applying these elements as foliar
fertilizers generally is ineffective. The main exception is sulphur on canola. A foliar application of
sulphur and boron prior to flowering has resulted in improved canola yields.

Sulphate sulphur sources can be band applied in corn starter fertilizers or in sidedressed UAN nitrogen.

110 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Choosing the Right Source of Calcium, Magnesium and Sulphur based on the Soil Test or Tissue Tests
Soil test results will measure calcium and magnesium as part of the analysis with potassium. Once
again, calcium and magnesium are closely related to soil pH. If soil pH is in range, the soil report will
indicate a requirement for magnesium if the test is below 20 ppm. These results will dictate if limestone
or other soluble fertilizer sources are required. There is currently no accredited test for soil sulphur. As
such, the recommendation is based on unique crop requirements. Currently wheat, canola and alfalfa
are indicated as crops with greater need for supplemental sulphur.

Tissue tests can measure plant nutrient tissue levels and compare them to a critical value. This value
is relevant if the timing and specific plant part(s) were collected and subsequently analyzed in an
accredited lab. Nutrient deficiencies will be indicated on a report.

Applying foliar calcium on field crops is not practical. Magnesium can be applied foliar as well as
sulphur. However, applying secondary elements as a foliar may provide short term alleviation of
a deficiency. Generally, it is impractical to spray these as a foliar application due to limitations in
applying sufficient quantities, and because these elements do not translocate within the plant from
the leaves to the area where the mineral is deficient. Foliar calcium is a standard practice in some
horticultural crops. It is only effective if calcium comes in contact with the plant part requiring the
calcium.

Choosing the Right Source of Calcium, Magnesium and Sulphur based on the Timing of Application
Choosing the correct source of these materials depends on soil tests, crop, cropping system and
equipment systems available to apply them

Calcium, magnesium and sulphur are best soil applied ahead of cropping needs. Calcium and
magnesium can be adjusted at the beginning of a cropping rotation cycle and move very little in the
soil. Liming practices often adjust calcium and or magnesium to desired levels. Sulphur, in particular
sulphate sources, is mobile in the soil and is best applied annually ahead of planting. Any number of
sulphate sources can be included in a crop plan depending on the crop needs for other nutrients.

Choosing the Right Source of Micronutrients based on Crop Type
Corn has a high requirement for zinc and responds best to soil applied zinc placed in starter bands at
planting time. Zinc sulphate is often the best choice followed by zinc oxy-sulphate blends that contain
at least 35% sulphate sources. Liquid sources that are compatible in liquid starter fertilizers are also an
option. Foliar products can be used but often times the application is too late to be of benefit.

Soybeans and cereals have a higher requirement for manganese. It is most effective to apply soluble
products as a foliar application to avoid soil reactions that reduce availability. Foliar applications that
are made within a few days after visual symptoms appear will prevent yield loss.

Forages, mainly alfalfa and vegetable root crops, often have a high requirement for boron. Soil
applications can be effective but there is also a need to apply boron foliar to some of the root crops to
maintain crop quality and enhance storage life.

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 111

Choosing the Right Source of Micronutrients based on the Cropping System
Crops in a crop rotation can have similar or differing micronutrient requirements. Corn and white beans
can have similar needs for zinc. It may be possible to build up zinc soil levels to handle the needs
of the second crop. Zinc sulphate or zinc oxy-sulphates could be used. Applying liquid products or
chelates may not provide sufficient quantities.

Applying boron for two crops may lead to toxicity regardless of the source used. Utilizing mixed
products that contain more than one element may not be beneficial to rotational crops.

Soil applying dry or liquid manganese sources is usually ineffective in reducing nutrient deficiencies.

Choosing the Right Source of Micronutrients based on the Crop Growth Stage
Micronutrient deficiencies are best addressed in the early growth stages on most crops. Some
micronutrients such as boron may require multiple applications at critical growth stages for crop quality
reasons.

Manganese on soybeans may require repeated applications based on severity and persistency of the
deficiency

Foliar applications require liquid formulations or water soluble powders dissolved in sufficient carrier
to make a spray solution. Using multi-element products may result in an application of a nutrient not
required for optimum yield.

Choosing the Right Source of Micronutrient based on the Soil Test or Tissue Test
Soil testing for micronutrients can be done. The accredited tests cover zinc and manganese but not for
boron in Ontario. Zinc index values below 15 indicate a greater chance for an economic response.

Soil applied products for zinc include sulphate and oxy-sulphate sources. Liquid chelated products are
not as effective in building soil test levels and are more expensive choices. Liquid sources are good for
foliar applications although waiting to treat zinc deficiencies may result in reduced ability to capture
yield responses.

Manganese, due to its highly reactive nature, is best applied as a foliar spray of a soluble product.

Plant tissue samples taken at the appropriate time and the correct plant part can confirm visual
symptoms or detect deficiencies that are not visible to the naked eye.

Foliar manganese applications of liquid or dry water soluble powdered products mixed in water carrier
and applied to sufficient leaf canopy will bypass soil reactions and provide a more rapid relief of
deficiencies.

112 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Choosing the Right Source of micronutrients based on the Timing of Application
In a well-designed, field nutrient plan based on soil tests, the micronutrient needs can be addressed
ahead of time. Soil application may be best for zinc and boron whereas a foliar program may be best
for manganese. Micronutrients are non-mobile in plants, therefore having an adequate supply in the soil
ahead of time is one of the better strategies for managing micronutrients. Any number of sulphates or
oxy-sulphates is an appropriate choice for soil application. If indeed deficiencies do occur, then foliar
applications are an option. For manganese, a foliar program is considered to be most effective using
liquid and soluble dry formulations. The earlier the deficiency is relieved, the higher the potential yield
capture.
Foliar boron, using water soluble sources, may be necessary for some speciality crops to improve both
yield and quality. Often times, an application just prior to reproductive stages improves storage quality
on root crops.
A soil applied spring application after first cut of alfalfa on coarse soils often is sufficient to reduce
deficiencies and improve crop growth and yields. A fall application may result in leaching losses.
Applying boron to crops that do not demonstrate a clear need may in fact actually cause a yield loss
due to toxicity.

Performance Objective 3
Discuss how managing the 4Rs for potassium, secondary macronutrients,
and micronutrients influences nitrogen and phosphorus losses to surface
water and groundwater.

One of the underlying principles of nutrient utilization and interactions in the 4R approach is best
described by Von Liebeg’s barrel. Also known as “The law of the minimum “. It is not how much nutrient
is in the soil of any one element but rather it is the element in the least amount of supply that determines
crop growth and subsequent nutrient utilization.
Von Liebeg’s Barrel - “The law of the minimum”

Source: Yara Crop Nutrition, http://yara.co.uk/crop-nutrition/
three-steps/step-1/, accessed March 31, 2016

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 113

Potassium Influence on Nitrogen and Phosphorus Losses to Surface or Groundwater
Potassium and Nitrogen
Nitrogen can be absorbed both as an anion and a cation. This presents a potential cation-anion
interaction with K or a cation-cation interaction. As nitrogen increases in the soil solution, the uptake
of phosphorus increases. This effect could be caused by a decrease in pH when there is a greater
amount of ammonium ions in the soil solution. Also, increased nitrogen uptake increases the rate of
translocation of phosphorus from the root to the plant shoot.

Plants supplied with predominately ammonium N (NH4+) require an adequate supply of K to increase
crop growth and reduce any potential toxicity caused by excess ammonium accumulation in the early
growth stages. No such issues are observed with nitrate sources. Numerous studies show the need
for increased K supply as N rates increase. Therefore, if N application rates are increased in a low
K environment then crop growth will be limited and N may be underutilized reducing nutrient use
efficiency and leaving unused N subject to environmental losses.

Potassium and Phosphorous
Potassium and phosphorus interactions are less evident in research literature. P uptake is independent
of K uptake. However, since both P and K are essential nutrients, normal plant metabolism requires
both to be present to build the necessary cation anion balance in plant cells and produce the desired
compounds for growth. One notable exception is the impact of K on the well-known P-Zn interaction.
Increasing levels of K reduce the influence of excessive P on zinc uptake (Stukenholtz et al, 1966). It
appears that K increases the exchange of Zn and Mn, increasing the supply of both and reducing the
negative effect of higher P availability.

With adequate K nutrition, overall plant metabolism is increased and all essential nutrients including N
and P are better utilized.

Influence of Calcium and Magnesium on N and P losses
Potassium (K), Calcium (Ca) and Magnesium (Mg)
These three cations are dominant in soil and soil solution. They are competitive at the root sites for
uptake. Excessive potassium can interfere with magnesium and to some degree Ca uptake. Conversely,
excess magnesium can depress K uptake. While no ratios are prescribed as being ideal, the effects
are known. A soil test and tissue test will offer insight into nutrient relationships. As stated earlier, Ca
and Mg are associated with the need for liming due to low soil pH. With proper pH, both N and P are
better utilized by the crop.

Documentation can be found on high K rates lowering Ca and Mg in plant tissues. It is often due to
dilution because of the stimulatory growth effects of K increasing crop growth and yield and demand
for N and P.

114 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Influence of Sulphur on N and P losses
Nitrogen and sulphur are both involved in protein synthesis. If the sulphate sulphur supply is low in the
soil then the nitrogen utilization may be limited as the sulphur supply becomes the first limiting factor
on crop growth. Increasing N rates without due consideration for S supply will reduce growth and
utilization of both N and P.
The ratio of N:S in plant tissues ranges from 7:1 to 15:1 depending on the species and the stage of
growth. Crops that receive high rates of nitrogen when sulphur supply from the soil is low can suffer
from induced sulphur deficiency. This has led to a common practice in western Canada of applying
one pound of sulphate sulphur to canola for every six to eight pounds of nitrogen. Ontario growers
may have to consider a similar practice for intensively managed canola, alfalfa, and wheat crops,
particularly if atmospheric deposition of sulphur continues to decline.
Influence of Zinc (Zn), Manganese (Mn) and Boron (B) on N and P losses
Zinc is important in early plant growth and in grain and seed formation. It plays a role in chlorophyll
and carbohydrate production. Plants that grow efficiently will use more N and P when adequate zinc
supply keeps plants growing and allowing them to metabolize normally.
Manganese is involved in photosynthesis and chlorophyll production. It helps to activate enzymes and
is involved in the distribution of growth regulators within the plant. Nitrogen and magnesium are key
elements in chlorophyll, therefore both adequate Zn and Mn keep plants metabolizing normally and
taking up N and P to meet desired production levels.
Boron plays an important role in the structural integrity of cell walls, fruit set, seed development, and
carbohydrate and protein metabolism. Plants that are adequately supplied with B will continue to use
N, P and other essential nutrients more effectively to make sugar and develop seeds which, in turn
depending on the crop, can be high in both N and P.
Plants that have access to all essential nutrients will metabolize more efficiently. Any essential nutrient
that is missing in a field nutrient program runs the risk of causing other nutrients that have been applied
for a specified yield goal to be underutilized and increase the risk of environmental loss if those
nutrients are N and P. Refer to Von Liebeg’s Barrel.

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 115

Competency Area 2
Determining the Right Rate of Potassium

Performance Objective 4
Interpret how soil test potassium levels relate to crop yield response and potential
environmental impacts.

The following table relates the soil test K level to a relative response rating and a recommended rate of
K2O available to the crop. In this case corn. Each crop type has its own recommendations.

Soil test rating Interpretation Possible Economic Response
HR Highly responsive High economic response to the application
MR Moderately responsive
LR Medium response to the application
RR Low response Low economic response to the application
NR Rarely responsive
Rarely pays to apply nutrients
Not responsive Applying nutrients almost always results in economic loss

A soil test level of 50 ppm results in a rating of HR - highly responsive to the recommended rate
of 110 kg/ha.

Table 4.4. Phosphate and Potash Recommendations for Corn Based on OMAFRA-Accredited Soil Tests

Ammonium Acetate Potassium Rating1 Potash (K2O)2 Required kg/ha
Soil Test (ppm)
0-15 HR 170
16-30 HR 160
31-45 HR 140
46-60 HR 110
61-80 MR 80
81-100 MR 50
101-120 MR 30
121-150 LR 0
151-250 RR 0
251+ NR3 0

Source: Agronomy Guide for Field Crops, Publication 811, OMAFRA, 2009, p. 22.

Applying potassium fertilizer in excess of the recommended rate mostly results in an economic loss in
the year of application. The choice of the fertilizer product and its accompanying ion may pose a risk
such as using potassium nitrate when nitrogen is supplied by another source.

116 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Performance Objective 5
Evaluate how soil moisture content and sampling
time may affect soil test potassium levels.

Field conditions at time of taking the soil sample may impact on the results. Field conditions that are
excessively dry may make it difficult to maintain a proper, consistent sampling depth which could
cause elevated K tests in no till or minimum till cropping systems. Drying and wetting of soil may also
influence soil test K results. Illitic and vermiculite clays can influence the amounts of exchangeable K
based upon their ability to fix K ions in the inner layers of the structure especially under dry conditions.

Exchangeable K can either increase or decrease upon drying and is dependent upon the
clay minerals present. Potassium fixation (K becomes non-exchangeable) can occur from drying
soils with high exchangeable K or recent K fertilizer applications. Fixation is a result of K
becoming trapped within clay sheets as they dry and collapse. This may result in a lower soil test value.
More K could be released in soils low in exchangeable K as they dry because the clay sheets roll back
and release K (McLean and Watson, 1985).

Thus, the time of soil sampling in relation to field wetting and drying cycles may influence soil test
levels. It becomes important to pay attention to these conditions and make an effort to sample at the
same time each year or if possible under similar conditions and be aware of current fertility practices
that may alter results due to recent fertilizer applications.

Performance Objective 6
Estimate how potassium rates may be affected by soil
characteristics, which may include:

a. cation exchange capacity (CEC);
b. organic matter;
c. texture;
d. clay type.

Cation Exchange Capacity (CEC)
Finer textured soils will have a higher CEC and hold and release more exchangeable K. As such, clay
soils tend to be higher in K and need less supplemental K added to meet production levels. In contrast,
low CEC sandy soils have a lower ability to hold sufficient K and may test lower in available K resulting
in the possible need for higher amounts and more frequent applications.

Organic Matter
Soil organic matter can act as a storehouse of some available K. However, organic matter increases the
CEC and nutrient holding power of a given soil imparting some of the same actions on exchangeable K
as the CEC.

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 117

Texture
Soil texture is influenced by the relative amounts of sand silt and clay. Higher clay soils will have
higher CEC (see CEC). Rates of application will be dependent upon soil test levels which are directly
influenced by texture and accompanying CECs.
Clay Type
Various clays exhibit differences in their ability to bind and release K which is also influenced by soil
moisture. Refer to Performance Objective 5 above.

Source: International Plant Nutrition Institute

118 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Performance Objective 7
Calculate potassium credits from:

a. previous potassium application;
b. manure;
c. biosolids;
d. irrigation water;
e. wastewater.

Previous Potassium Application
It is expected that applications were made based on a soil test, as such, the rate applied was based
on need. If for an unforeseen situation, such as drought, yields were lower than expected, the need to
calculate carryover or a credit is really of little consequence. Always base fertility needs on a soil test. If
fertility was not removed then the soil test values should be higher reflecting the need for lower rates of
application going forward.

Manure
Use the NMan calculator or manual worksheets. You will need to know the type of manure, either book
values or a manure test, and rates of application to determine the K credits applied per hectare or acre.

The formula below shows how to calculate the available K20. Some labs may already have done these
calculations. If a manure analysis is not available, use the typical manure analysis by livestock type.
Refer to the chart contained in Performance Objective 9, Proficiency Area 5, Manure Management.

Convert to Metric Convert to Imperial
multiply by 10
% kg/1,000 L multiply by 10 % lb per 1,000 gallons multiply by 100
% kg/tonne divide by 10,000 20
mg/L % % lb per ton multiply by 10,000

ppm % divide by

Available K2O: X 10 = _____kg/1,000 L/tonne
Percent K ___ x 1.08 = _____ % available K2O X 100 =_____ lb/1,000 gal
X 20 = _____lb/ton

As an example, if the K content of manure was 0.17% and it was liquid manure
K credit in kg/ te = % Total K x 1.21 x 10 x 0.9
K credit as Kg/te = 0.17 x 1.21 x 10 x .90

= 1.85
Assume an application of 5000 lt/ha (1 lt = 1kg). Therefore 5 te applied.
Total applied K2O = 5 X 1.85

= 9.25 kg / ha
Biosolids – same as for manure above

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 119

Irrigation Water
This will require a water test to determine the level of K and application rates over the season in terms
of acre inches (cubic meters) of water applied. The kg of K applied per ha is determined by ppm K *
0.00113 * cubic meters of water applied/ha
Example: A water test reveals 5 ppm K and 1020 cubic meters are applied per/ha/season
5 ppm *0.00113 * 1020 = 5.76 kg/ha of K (multiply by 1.2 to equate to K2O) which is
6.91 kg/ ha of K2O
Waste Water – refer to manure and irrigation water.

Performance Objective 8
Justify the rate of potassium applied based on potassium placement.

Potassium is a relatively non-mobile nutrient and, as such, it should be placed into the root zone for
optimum uptake by plant roots. The recommended rate of potassium is based on soil tests. Efficiencies
from placement are not considered for K as there is a need to apply at appropriate rates due to
relatively large quantities taken up by plants.
Often times, the safe rate of banded K fertilizer with nitrogen determines the optimum rates for banding
versus broadcasting.
There is Ontario research supporting the inclusion of small amounts of K in a starter fertilizer on corn in
low K testing soils. However, yields were maximized with additional broadcast K.
On forages, the only option is to surface broadcast to meet crop requirements. K is sufficiently mobile
to reach near surface feeder roots. However, prior to the year of establishment, it is advised to apply
and incorporate K into the root zone. Often early spring or fall applications just prior to fall rest
period are good times to apply due to the likelihood of higher rainfall events to move K into the soil for
established stands.

120 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Competency Area 3
Determining the Right Timing of Potassium Application

Performance Objective 9
Discuss how the timing and method of potassium
application can impact crop response.

Two guiding principles of potassium placement and timing relate to K mobility in the soil and relative
large amounts of K needed by crops.

Potassium moves only short distances by the process of diffusion. This necessitates the need to place K
where the roots are actively growing to be in a position for optimizing uptake. Placing small amounts
of K in starter bands assures early season uptake. Placing the bulk required into the soil root zone,
either by broadcasting and incorporating or utilizing placement technology such as strip tillers to place
K in concentrated bands to produce a nutrient rich zone, will facilitate K uptake.

Surface applying and not incorporating K may not place sufficient quantities into the root zone for
optimal uptake. Potassium ions only travel short distances at a relatively slow speed of approximately
0.1 cm/day (Tinker G.S. Sekhon, Potash Research Institute, India, 1978).

Table 4.5 contains data from Ontario research trials that evaluated corn grain yield response to various
starter fertilizers. When soil-test K levels were less than 90 ppm and no broadcast K was applied,
applying a MAP/potash blend in a 5 cm x 5 cm (2 in. x 2 in.) starter band increased corn yields
significantly. In these same circumstances, seed placed liquid fertilizers that also contain a small amount
of K can be expected to produce higher corn yields than where no starter fertilizer is used or where
starter fertilizers contain P only. On these lower testing soils, when K is broadcast prior to planting
(fall or spring) yields, are improved significantly by the broadcast K and the magnitude of the yield
response due to the starters is reduced (Refer to Table 4.5).

The data generally indicates that broadcasting K on the lower testing soils is advised, but in situations
where land tenure is in question and broadcasting a significant amount of K to build soil tests is risky, a
grower who has the capability to band dry fertilizer P and K blends can generate yields equivalent to
other options.

On higher testing soils, the size of the yield responses to any applied K is much less. However, some
of the same trends are observed. Some K in a starter band can improve yields, but generally the
advantage to higher K rates in dry 5 cm X 5 cm (2 in X 2 in) bands compared to lower in-furrow rates
is marginal.

If broadcast K is to be applied either in the fall or spring prior to corn planting, the need for K in the
starter is significantly reduced unless soil tests are low (i.e. less than 61 ppm). In these low testing
situations, broadcasting to build soil test and banding to help meet the immediate crop requirements
are likely both profitable.

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 121

The following table illustrates the impact of soil test K, placement methods, and fertilizer sources on
corn yield.

Table 4.5. Impact of Broadcast K Applications and Various Starter Fertilizer Options on Corn Yields.

Soil Test K (ppm) Convert to Imperial No Broadcast K Broadcast K

Bu/ac Tonnes/ha Bu/ac Tonnes/ha

none 120 7.6 156 9.8

< 90 6-24-6 (liquid in furrow) 139 8.7 158 9.9

P and K (dry in 2X2 band) 168 10.4 166 10.5

none 176 11.0 186 11.7

> 90 6-24-6 (liquid in furrow) 186 11.7 192 12.0

P and K (dry in 2X2 band) 190 10.9 195 12.2

6-24-6 applied at 47 litres/ha (5 gal/acre)
P and K applied at rates of 35-62 kg/ha (31-55 lbs/ac) of P2O5 and K2O each in a blend
Soil test averages for sites in the < 90 group averaged 71 ppm K and 21 ppm P
Soil test averages for sites in the > 90 group averaged 122 ppm K and 27 ppm P

Chart source: Stewart, G., Janovicek, K., P and K Considerations in Corn, OMAFRA 2014,
http://www.omafra.gov.on.ca/english/crops/field/news/croptalk/2014/ct-1114a1.htm, accessed April 1, 2016

Competency Area 4
Determining the Right Placement/Method of Application for Potassium

Performance Objective 10
Discuss considerations to determine the proper placement and method of
application of potassium based on the:

a. crop type;
b. cropping system;
c. methods of tillage.

Crop Type
Placement of K for various crop types will be dependent upon a number of factors including:

• perennial versus annual;
• K demand;
• safe rates;
• root structure - tap, fibrous;
• field variability of K;
• soil texture; and,
• cropping system.

Perennial versus Annual
Perennial crops may have larger or smaller demands for K. Tree fruits may have smaller annual
demands whereas alfalfa will have much larger demands. Applications may be limited to broadcast
applications with no soil disturbance whereas other crops with drip irrigation may provide for a more
timely application method throughout the season to meet demands.

122 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Potassium Demand
Some crops have higher K demands than others; this may necessitate a combination of placement
options to apply sufficient quantities to meet early and later season uptake patterns. Potatoes and
tomatoes may require applications split between pre-plant, banding in the seed bed and a final layby
with nitrogen just prior to row closure

Table 4.6. Field Crop Nutrient Uptake and Removal in Ontario

Crop Yield N* P2O5 K2O Ca Mg S
bu/ac
lb/ac

GRAINS, OILSEEDS

Grain corn 150 uptake 173–23 74–109 133–243 26–49 18–3 13–16
removal 97–149 55–66 39–44 1 13 10–11

Soybean 50 uptake 230–29 40–50 120–220 25–30 20–25 17
removal 187–200 40–44 69–70 9–11 7–9 5

Winter wheat 75 uptake 140–15 51–56 94–152 13 17–23 15–19
removal 86–94 41–47 26–28 2 12 6

Barley 75 uptake 93–112 36–41 75–112 17 8–13 13–15
removal 65–83 28–30 19–26 2 46

Oats 75 uptake 70–86 30–33 89–109 9 10–15 14
removal 47–60 19 14–15 2 3 5

Winter rye 50 uptake 83–84 28–42 50–120 13 7 14–15
removal 54–61 17–23 17–18 3 4 5–10

Dry beans 30 uptake 75 25 25 2 2 5
removal

Canola 45 uptake 135–144 59–75 107–120 ** ** 27–28
removal 90–100 50–60 25–30 9–12 12–15 15

FORAGES TON/AC DM†

Corn silage 8 173–239 74–109 133–243 26–49 18–30 13–16

Legume haylage 5 266–367 53–79 224–354 113–177 19–36 19–20

Mixed haylage 5 228–338 52–78 224–355 95–164 16–34 15–29

Grass haylage 4 129–219 39–62 163–287 42–90 10–21 **

Legume hay, 1st cut 5 223–331 52–80 206–350 101–154 21–34 19–27

Mixed hay, 1st cut 5 172–273 50–72 170–297 82–135 18–30 13–21

Grass hay, 1st cut 4 103–181 35–56 111–224 42–85 11–21 11–16

Hay, 2nd cut 3 152–215 34–47 119–191 68–102 14–23 11–17

* Soybeans, dry beans, forage legumes get most of their nitrogen from the air. † Tons per acre of dry matter
**Data not available
Ranges of nutrient uptake and removal for yield levels typical of good growing conditions for field crops. Figures are based on Ontario field data where possible and are estimates.
Actual uptake and removal will vary with yield, and nutrient concentrations will also vary with year, level of soil fertility and crop variety. Precise nutrient management planning
would require analysis of each crop each year. Actual changes to soil fertility may differ from the amount removed by the crop. In some instances, weathering of soil materials
and organic matter may compensate for part of the nutrient removal by crops. In other instances, nutrients may be chemically fixed by the soil or lost to leaching, and the loss of
nutrients will exceed crop removal.

Chart source: Soil Fertility Handbook, Publication 611, OMAFRA, 2006, p. 146.

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 123

Table 4.7. Horticultural Crop Nutrient Uptake and Removal Ontario

Crop Yield N* P2O5 K2O Ca Mg S
ton/ac
lb/ac ** 21 **
** ** **
Beans, green 5 uptake 170–173 16–41 100–204
10 55 ** ** **
removal 120 ** ** **

Broccoli 5 uptake 165 10 210 84 35–36 64–77
removal 20 2 45 84 35 64

Cabbage 35 uptake 225–270 63–84 249–280 ** ** **
84 280 ** ** **
removal 225
** 27 15
Carrot 25 uptake 145 25 345 ** ** **
removal 80 20 200
30 12 25–48
Corn, sweet 6 uptake 155–187 20–63 105–181 29–30 5–12 29–48
8 30
removal 55 ** 29 16
** ** **
Onion 20 uptake 120–145 25–53 105–155
removal 110–120 20–53 105–110 ** 40 18
5 10 10–12
Peas, green 2 uptake 170–260 22–56 80–168
10 30 ** 59 32–33
removal 100 ** ** 13

Potato 20 uptake 215–228 66–72 298–437 ** 16 13
removal 128–133 37–50 216–250 75 18 14

Sugar beets 22 uptake 186–211 29–67 386–403 ** 36 54
removal 88–92 11–40 143–183 14–24 22–24 28

Tobacco 1 uptake 84–110 17–30 170–171 ** 24 **
removal 56–75 10–15 104–120
** 9 **
Tomato 40 uptake 232 87 463
removal 144–160 48–68 280–288 11 ** **

Apple 12 uptake 100 46 180

Grapes 6 uptake 51 18 80

Peaches 15 uptake 50 20 60

Ranges of nutrient uptake and removal for yield levels typical of good growing conditions for horticultural crops
* Legumes such as beans and peas get much of their nitrogen from the air
** Data not available

Chart source: Soil Fertility Handbook, Publication 611, OMAFRA, 2006, p. 147.

Annual crops such as cereals, oilseeds and corn can have numerous placement options, broadcast
in the fall or spring and incorporated, or applied pre-plant and some in the starter or popup band. If
the soil test indicates a small amount of K, less than 25 kg, it may be included in a 2 x 2 starter band
as long as the maximum safe rates are followed. Higher rates of K could be included depending on
nitrogen rates.

124 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Safe Rates

Table 4.8. Maximum Safe Rates of Nutrients

Crop N (Nk+g/Kh2aO)
(kg/ha)

SPRING OAT AND BARLEY (FERTILIZER WITH SEED)

Sands, sandy loam

Urea (46-0-0) 10 30

Di-ammonium phosphate (18-46-0) 20 35

Other fertilizers 35 55

Loams, silt, clay loams

Urea (46-0-0) 10 30

Di-ammonium phosphate (18-46-0) 30 55

Other fertilizers 45 70

WINTER WHEAT, TRITICALE OR BARLEY (FERTILIZER WITH SEED)

All soils

Urea (46-0-0) 0 (fall) 0 (fall)

Di-ammonium phosphate (18-46-0) 0 (fall) 0 (fall)

Other fertilizers 15 30

CORN (FERTILIZER BANDED WITH THE SEED)

All soils

Urea (46-0-0) 00

Di-ammonium phosphate (18-46-0) 00

Other fertilizers - 100-cm rows 7

- 75-cm rows 10

- 50-cm rows 14

Note: Sweet corn can be more sensitive to fertilizer placed with the seed. Do not apply fertilizer with the seed of super sweet
hybrid sweet corn.

CORN (FERTILIZER BANDED 5 CM TO THE SIDE AND 5 CM BELOW THE SEED)

All soils

Urea (46-0-0) 40 60

Other fertilizers 55 90

At higher rates, band at least 15 cm from seed. At row widths other than 100 cm, the rate may be adjusted to provide the same
maximum concentration in the row (e.g., in 50-cm row, the safe rate = 100/50 x 55 = 110 N).

CORN (FERTILIZER BROADCAST)

Sands, sandy loam

Urea (46-0-0) 200 250

CANOLA (FERTILIZER WITH THE SEED)

Up to 20 kg/ha phosphate fertilizer may be drilled with the seed as superphosphate or mono-ammonium phosphate. Do not apply
N (except as mono-ammonium phosphate) or K with the seed.

FLAX (NO FERTILIZER WITH THE SEED)

Rates recommended are normally safe when broadcast.

PEAS, BEANS AND SOYBEANS (NO FERTILIZER WITH THE SEED)

All soils, fertilizer banded 5 cm to the side and 5 30 90
cm below the seed

Source: Soil Fertility Handbook, Publication 611, OMAFRA, 2006, p. 171.

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 125

Fertilizers containing more than half as much N as P2O5 (e.g.16-16-16) often contain urea. Fertilizers
containing urea are not suitable for banding at seeding in many cases.

Root Structure
Fibrous roots tend to be near the surface and have a greater surface area. They may be able obtain
adequate K from shallow broadcast placement with adequate soil moisture. In a dry year, the K may
not be available to the roots. A continued practice of surface broadcast with minimal incorporation
may result in nutrient stratification.

Taproots tend to be deeper and occupy lower soil volume. Placement throughout the root zone with a
combination of banding and broadcasting at various depths may augment K uptake.

Field Variability
Field variability of K may also influence placement and method. If the K test across a field landscape
is highly variable, the demand for K may increase. A number of options exist. A single rate of
application may be justified based on economic response from the lower testing areas or, a preferred
variable rate targeted application that is best done by broadcast or strip till depending rate and on the
technology available.

Table 4.9. Influence of Soil Test K Variability on Optimum K Fertilizer Rate in Ontario

Average soil test K ppm Uniform Soil test variability Moderate High
optimum K2O rate (kg/ha)
106
45 100 101 77
58
90 50 58

135 0 30

Source: Kachanoski and Fairchild, 1994. Coefficient of variation for low variability site = 0%, medium = 53% and high = 131%.

Chart source: Soil Fertility Handbook, Publication 611, OMAFRA, 2006, p. 140.

The image below illustrates variability of soil test
K across the field. The field average is 128 ppm
of K but ranges from 88 to 196 ppm of K. This
creates an opportunity to practice 4R stewardship
and target the application to the area(s) of
greatest need.

Source: AGRIS Cooperative, 2016

126 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Soil Texture
There are inherent differences in soil textures. Sand, loam and clays will have different K contents and
will influence the K soil test and subsequent recommendations. Sands with low buffering capacity will
require more frequent applications. Clays will require, as a rule, less frequent applications due to
higher buffering capacities. Loams fit in between. Soil textures may limit spring applications. Sandy soil
may tolerate an extra pass for application in the spring whereas clays may not be conducive to extra
traffic or deeper placement technology for fear of soil compaction. Fall application may be preferred
on clay soils. Loams may afford many more options for either fall or spring applications.

Cropping System
The cropping system or rotation sequence may require different approaches based on K demand of the
crops in the rotation. Planning ahead for opportune times to effectively apply and place K in the root
zone should be considered. Often, looking at the entire K needs for four-year rotation will offer insight
into K needs and placement methods.

The following table illustrates the differing amounts of K2O required in a typical crop rotation for
a dairy operation. One can readily see the crops with the greatest need and can plan a nutrient
application strategy to address the K demands ahead of time. Corn silage K applications could be
addressed the fall before or in the spring. Alfalfa could be fertilized a year ahead with annual
top-dressing after each cut or ahead of the fall rest period. Barley needs could be done at
planting time.

Crop Yield te/ha K kg / ha
Corn silage 17 200
3 years of alfalfa 33 963
2 24
Barley 1187
Total

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 127

Performance Objective 11
Estimate the proper placement and method of application of potassium based on
current potassium soil test levels and soil texture.

Example: Basic soil test information, fall application for a new seeding:

Crop K ppm Texture
Alfalfa 65 F

The OMAFRA recommendation at 65 ppm is 200 kg per ha of K2O. Broadcast applying a year ahead
in the early fall and incorporating all the potash into the root zone may be the best option. Alfalfa has
a high K demand and potassium has limited soil mobility so placement into the root zone where the
roots will be actively growing will enhance K uptake.

This is a fine-textured (F) or clay soil therefore there will be no issue with K leaching as clays tend to
have higher CEC. If this was C textured soil, for a coarse or sandy soil texture, we may opt for a lower
rate for spring application ahead of seeding to reduce potential K leaching due to lower CEC and
apply more frequently after each cut and before the fall rest period.

Table 4.10. Potash Requirements for Forages Based on OMAFRA - Accredited Soil Tests

Ammonium At Seeding With or Without Nurse Crop Fall Applications for New Seeding
Acetate Potassium and Established Stands

Soil Test (ppm) Rating1 RPeoqtuaisrehd(Kk2gO/)h2a Rating1 RPeoqtuaisrehd(Kk2gO/)h2a

0-15 90 480

16-30 80 400

31-45 HR 70 HR 320

46-60 50 270

61-80 40 200

81-100 30 130

101-120 MR 20 MR 70

121-150 20 20

151-180 LR 0 LR 0

181-250 RR 0 RR 0

251+ NR3 0 NR3 0

Chart source: Agronomy Guide for Field Crops, Publication 811, OMAFRA, 2009, p. 68.

128 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Competency Area 5
Determining the Right Rate, Timing and Placement
of Secondary Macronutrients

Performance Objective 12
Discuss considerations to determine the proper rate, timing and
placement of magnesium based on the:

a. crop type;
b. cropping system;
c. crop growth stage;
d. soil test or tissue test;
e. timing of application;
f. method of application.

Consideration for magnesium (Mg) is often addressed if a limestone application is required.
Depending on soil test Mg level, dolomitic lime may be the appropriate choice and would be applied
broadcast and incorporated into the root zone (see P.O. 18 for more details). If lime is not needed
and the Mg soil test is below 20 ppm, then supplementing with one of many soluble magnesium
sources such as magnesium sulphate or sul-po-mag if potassium and sulphur are also required. The
recommended rate is 30 kg/ha of Mg.

Placement options can be in starter bands or broadcast and incorporated. Magnesium has limited
mobility but greater than both K and Ca. It is still best to soil apply and incorporate into the root zone.
Mg uptake can be reduced in high K soils and may impact on livestock consuming forages grown
under those conditions. Monitor soil test and avoid excessive K applications.

Crop Type
Mg is an essential nutrient and plants require adequate amounts to grow normally. Most of the uptake
occurs during vegetative stages of growth much like K. Having a balanced supply in the soil at all
times, will aid in uptake and meet crop demands.

Cropping Systems
Crop rotations that contain forages may have a more critical need to watch both K and Mg soil test
levels. Excessive K will reduce Mg uptake in forages, this may be a health concern when livestock
consume forages testing low in Mg. Managing the crop rotation with current soil tests and addressing
pH, K and Mg levels throughout the rotation, should avoid any Mg nutritional issues.

Crop Growth Stage
The greatest need for Mg is during the vegetative growth stages. Therefore, maintaining proper pH and
soil test Mg level should meet nutrient demands of a majority of Ontario crops.

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 129

Soil Test and Tissue Test
Mg is easily determined by a soil test. Maintaining Mg above 20 ppm and proper soil pH are two
of the factors a soil test can monitor. Plant tissue testing at the appropriate time and collecting the
proper plant parts can offer insight into Mg uptake. Plant tissue reports from accredited labs offer an
interpretation based on a critical tissue content level. There are often other circumstances that can
influence tissue test levels.

“High levels of the other cations, such as ammonium (NH4+), potassium (K+), and calcium (Ca2+),
can compete with Mg for plant uptake and effectively reduce the amount of Mg taken up by the
plant. Magnesium, NH4+, and Ca2+ ions are primarily taken up via a mechanism called mass flow
that is dependent on the amount of water the plant removes from the soil and transpires through the
leaf stomata openings to cool the leaves. The cations move with the water flow and are taken up and
accumulated by the plant. Excessive moisture present in the soil and high relative humidity may reduce
the amount of water that the plant can transpire. This may be one factor causing lower uptake. Often
times a little detective work is required to understand what has occurred and what some of the other
influences are that are impacting on tissue levels”.
Richard Taylor, Extension Agronomist; [email protected]

If the soil test is low in Mg or pH needs adjustment, then an application to the soil of an appropriate
source ahead of planting will remedy the shortages. If plant tissue reveals deficient Mg levels then a
foliar application may be required to keep plants growing normally. However, Mg is a secondary
nutrient usually required in amounts beyond what single foliar application may provide. Depending
on crop and crop growth stages, it may be possible to soil apply Mg and gain a response such as
banding Mg with sidedress nitrogen at V5 growth stage for corn. As the season progresses, fewer
options are available that make agronomic or economic sense.

Timing of Application
Mg can be applied with other nutrients when it fits in with other nutrient application operations in
either fall or spring. As stated previously, the greatest demand is during vegetative growth stages. With
limited soil mobility, it is best applied ahead of time into the root zone for optimum uptake.

Method of Application
The preferred method is a soil application, in either a starter band, strip till or broadcast and
incorporated. A need for lime will require a separate field operation. Foliar applied Mg sources are
the least effective method of application due to the quantities that may be required.

130 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Performance Objective 13
Discuss considerations to determine the proper rate, timing and placement of
calcium based on the:

a. crop type;
b. cropping system;
c. crop growth stage;
d. soil test or tissue test;
e. timing of application;
f. method of application.

Considerations for calcium (Ca) follow very closely those of magnesium. Ca is often associated with
the need for limestone applications. The choice of lime is dictated by the Mg soil test level. If it is above
100 ppm then choose calcitic lime (see P.O. 18).

There are some special considerations beyond the pH adjustment. Soils testing low in Ca (<350 ppm)
may have cropping situations where a response can be obtained from added Ca application. A
number of cole crops will have a higher need based mostly on quality, storage and extended shelf life.
In some plant diseases, such as club root, elevated soil Ca levels along with other mitigating practices
help reduce incidence and severity. At this point, there are no provincially approved recommended
rates for Ca applications. Farmers are often using best judgement, economics, product availability and
crop experience to determine rates on their farms.

Crop Type
All crops need calcium. For the most part, Ontario soils are well supplied with Ca. Keeping soils in the
proper pH range is a best management practice to assure adequate Ca supply.

Cropping System
A regular soil test program will help insure an adequate supply of Ca. If pH sensitive crops are in the
rotation, it may be critical to make soil adjustments one or two years ahead of time. Potatoes are a crop
that do best at pH less than 6.0 whereas wheat in the rotation may do best at pH 7.0. This rotation
would pose potential issues in optimizing both crops based on the time it takes to adjust pH and rarely
can pH be brought down quickly or economically enough to be effective.

Crop Growth Stage
Ca uptake is greatest during the vegetative growth stages. Very little Ca is translocated to the grain.

Soil Test and Tissue Test
Soil tests are very effective in determining Ca levels. Although it is not an accredited test it is extracted
at the same time as K and Mg and therefore is easily reported. Although the extracted calcium value
may be compromised by soils containing excessive amounts of free lime. Tissue tests can also determine
Ca uptake. Interpretation of tissue test results are dependent upon collecting the sample at the correct
growth stage and plant part. The results are compared to a critical level based on those parameters.
Because soils usually contain high calcium levels, any soil splash onto plant parts could skew the results
to a high bias. Careful sample preparation is required

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 131

Timing of Application
Calcium needs are best addressed ahead of planting, usually associated with lime applications to
adjust pH. Depending on lime quality, it may require more than 12 months to react and make a full
adjustment to the targeted pH. In some horticultural crops, there is a practice of applying multiple
foliar applications of calcium, in particular on apple and other fruit trees. In potatoes, applying calcium
sulphate in the seedbed at planting aids in better tuber sizing and storage quality.

Method of Application
Applications for calcium are often associated with limestone (see P.O. 18) with no official
recommendation for supplemental Ca. Other application techniques are adopted from farmer
experience. Generally, granular gypsum is applied in starter bands on potatoes and tomatoes and/or
broadcast treatments applied ahead of time and incorporated.

Performance Objective 14
Discuss considerations to determine the proper rate, timing and placement of
sulphur based on the:

a. crop type;
b. cropping system;
c. crop growth stage;
d. soil test or tissue test;
e. timing of application;
f. method of application.
g. atmospheric deposition of sulfur.

Crop Type
Supplemental sulphur requirements have been identified and confirmed on canola, alfalfa and wheat in
Ontario.

Recent studies in Ontario on winter wheat indicate a 10 lb application rate of sulphate sulphur applied
in the spring with nitrogen was the optimal rate. There were some sites with up to a 20 bushel yield
penalty without sulphur from sulphate sources applied.

Yield response of the six responsive sites show maximum benefit at 10 lbs/ac of sulphur, with no
additional yield gain from increased sulphur rates (see graph below). This is a critical finding, as it
gives an application level above which growers can expect no response. With variable winter wheat
yield responses across locations and years, many growers will opt to apply some sulphur. A yield
penalty of 20 bu/ac has been observed when no sulphur is applied on deficient fields. If a small
amount of sulphur can be applied to avoid a significant yield loss, and average yield gain will cover
the cost of this application, many growers will consider this a reasonable “insurance” application; 10
lbs/ac sulphur would appear to be that breakpoint.

132 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Sulphur Response at Six Responsive Sites (P=0.05)

Source: Johnston, P., Field Crop News, Do I need to apply sulphur to winter wheat?, April 3, 2013, www.fieldcropnews.com, accessed April 1, 2016

Alfalfa has the highest S requirements of any of the field crops. A five ton/ac crop of alfalfa removes
about 25 lbs/ac of sulphur. By comparison, a 45 bu/ac spring canola crop, also a high user of
sulphur, removes 15 lbs/ac. A 150 bu/ac corn crop removes 10 lbs/ac of sulphur.
Rates of sulphur on forages for Ontario are still being researched. Other jurisdictions suggest five to
25 lbs of S per tonne of production. A general thumb rule for S application on alfalfa is 5 lb/ac per
ton of dry matter yield. The University of Wisconsin recommends 15 - 25 lbs/ac of S in the sulphate
broadcast on established stands, or 25 - 50 lbs/ac of elemental S incorporated at seeding.
In Ontario, sulphur deposition from acid rain has decreased steadily. The amount of S deposited has
decreased by over 50% since 1990. Instances of S deficiency have also increased due to reductions in
the organic matter pool, higher crop yields and higher protein yields. S deficiencies in alfalfa are more
likely to occur on soils that have not had a manure application within two years
There currently is not a reliable soil test for sulphur in Ontario. However, tissue testing of alfalfa (at
late-bud stage) is considered a suitable diagnostic approach for determining sulphur deficiencies. The
critical level below which alfalfa is considered S deficient and may benefit from applying sulphur is
0.25%. A 2012 field survey of Ontario alfalfa stands indicated that 21% of fields had S-tissue analysis
below this level. Put another way, 79% of these fields would have been unlikely to have an economic
response to applying sulphur. It is also noteworthy that 37% of these fields tested below the critical K
value of 1.7%.
Recent trials support a 15 to 25 lb per acre application sulphur from sulphate sources on canola.
Cropping System
Sulphur needs within a rotation will be mostly based on the crop and crop demand for sulphur. From
previous research, a canola, wheat rotation would have significantly greater demand for S than a corn
soybean rotation. If you add in forages, it becomes even greater.

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 133

Crop Growth Stage
The timing of sulphur demands is similar to N as both are linked to the formation of protein. Applying
N and S together has been a common practice. The plant available form is sulphate and can be
prone to leaching losses over the winter so applying with N in the spring is a good practice. Most S is
applied with a nitrogen source such as ammonium sulphate. The exception to this is in alfalfa where a
fall application of elemental S seems to offer sufficient availability by being converted to sulphate forms
over winter and early spring in time to meet uptake demands.

Soil Test or Tissue Test
Currently, in Ontario, there is no accredited soil test for S. Other jurisdictions do offer them but use them
with caution. There are many factors influencing the utility of the test and questions around consistent
predictability of S responses to low soil test. Plant tissue tests are offering some insight on alfalfa from
Ontario based research.

Tissue testing of alfalfa (at late-bud stage) is considered a suitable diagnostic approach for determining
sulphur deficiencies. The critical level below which alfalfa is considered S deficient, and may benefit
from applying sulphur, is 0.25%.

Timing of Application
The plant available form of S is sulphate which is an anion and moves freely in soil solution. This fact
would indicate that a spring application, most likely with N, is the preferred timing. The only exception
is elemental S fall applied on forages. It will take 10 to 12 months to convert to plant available
sulphate.

Method of Application
The method of application may be dictated by the N application method as most economical and
agronomic significant sources of sulphate S are mixtures with N such as ammonium sulphate.
Generally, broadcast and incorporated, or top-dressed in the case of wheat or possibly canola, are the
main application strategies. Placing S in a starter band is also an option when higher rates of N in the
starter are also being addressed.

Potassium sulphate is another source that is usually applied when potash is applied and is the single
most expensive form of K and S. Foliar applications generally do not supply sufficient S, the exception
may be to apply foliar S to canola that is suffering from chronic S deficiency. Foliar application on
wheat has not been successful.

Atmospheric Deposition of Sulphur
Over the past 30 years, there has been a significant reduction in wet deposition of sulphur from
rainfall. This is mostly attributed to efforts to reduce industrial discharge of sulphur compounds into
the air from large industrial emitters and removal of S from diesel fuel. The result is less sulphur being
added to the soil and the beginning of observations and evidence to support the need to supplement
crops with S for optimum yields. The graphic on the next page illustrates the reduction in deposition of
sulphate sulphur in our region from 40kg/ha in 1990 to less than 12 kg/ha in 2010. With a crop like
alfalfa removing more than that amount in each cut, it is one of the reasons why we are seeing such
large responses to additional S in forages.

134 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Changes in Annual Wet Sulfate Deposition, 1990-2010

1990 Annual Wet Sulfate Deposition

2010 Annual Wet Sulfate Deposition

Source: Canada-United States Air Quality Agreement Progress Report 2012, Environment and Climate Change Canada, www.ec.gc.ca , accessed April 1, 2016.

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 135

Competency Area 6
Determining the Right Rate, Timing and Placement of Micronutrients

Performance Objective 15
Discuss considerations to determine the proper rate,
timing and placement of zinc based on the:

a. crop type;
b. cropping system;
c. crop growth stage;
d. soil test or tissue test;
e. timing of application;
f. method of application.

Micronutrient needs vary by crop type. One of the first steps is to identify the micronutrient requirements
of individual crops throughout the rotation. The table on the next page illustrates response to
micronutrients for some of Ontario’s agronomically important crops. Crops with a high demand are
most likely to be responsive to additional applications if a suitable soil test indicates a need.

Foliar application of micronutrients.

Photo courtesy of New Holland - Agriculture

136 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Table 4.11 Response of Crops to Micronutrient Fertilizers

Manganese Boron Copper Zinc Molybdenum

alfalfa low high high low med

barley med low med low low

clover med med med low high

corn med low med high low

edible beans high low low high med

oats high low high low low

rye low low low low low

soybeans high low low med med

wheat high low high low low

asparagus low low low low low

broccoli, med high med high
cauliflower

cabbage med med med low med

carrots, parsnips med med med low low

celery med high med low

cucumbers high low med

lettuce high med high med high

onions high low high high high

peas high low low low med

peppers med low low med

potatoes high low low med low

radishes high med med med med

red beets high high high med high

spinach high med high high high

sugar beets high med med med med

sweet corn high med med high low

tomatoes med med high med med

blueberries low low med

Highly responsive crops often respond to micronutrient fertilizer if the micronutrient concentration in the soil is low. Medium responsive crops are less likely to respond, and low
responsive crops do not usually respond even at the lowest soil micronutrient levels.
Source: Michigan State University Publication E-486. Secondary and Micronutrients for Vegetables and Field Crops, 1994.

Chart source: Soil Fertility Handbook, Publication 611, OMAFRA, 2006, p. 72.

Crop Type
From the table above, you can determine the crops with a high Zinc (Zn) demand. Crops such as
corn and edible beans would be crops that a grower should pay attention to regarding the need for
supplemental zinc. In contrast, a crop such as wheat has a lower requirement.

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 137

Cropping System
The crops in a crop rotation will draw more on the soil zinc supply; a rotation of corn and edible beans
with higher Zn demands may require a more frequent application. Zn is a nutrient that has limited
mobility and could be soil applied ahead to meet crop demands in future years. A corn, soybean and
wheat rotation may only require Zn supplementation for the corn. Applying Zn in a starter band is
likely the most efficient way to position Zn for uptake. With limited mobility in both the soil and the
plant, placing Zn in the root zone will optimize uptake.

Crop Growth Stage
The demand for micronutrients is generally important in the early vegetative growth stages although
recent research has demonstrated a season long uptake pattern.

Soil Test or Tissue Test
There is an accredited test for Ontario using the DTPA extraction method and reporting the value as an
index that is modified by soil pH. The critical index is 15; any values below would indicate a need for
zinc on high demand crops.

Table 4.12 Zinc Soil Index Interpretation

Zinc Soil Index1 Suggested Treatments

Greater than 200 Contamination of the sample or of the field is likely.

25 to 200 Soil zinc availability is adequate for most field-grown crops.

15 to 25 Zinc availability is adequate for most field crops. If the field sampled is uneven in soil texture,
pH, or erosion, some areas may respond to zinc applications.

Less than 15 Zinc is likely to be deficient and should be applied in the fertilizer.

Zinc Index = 203 + 4.5(DTPA extractable zinc in mg/L soil) - 50.7(soil pH) + 3.33(soil pH)2

1. These values are indices of zinc availability based on extractable soil zinc and soil pH.

Source: Micronutrients – Soil Diagnostics, Ontario Crop IPM, http://www.omafra.gov.on.ca/IPM/english/soil-diagnostics/micronutrients.html, accessed April 4, 2016.

When zinc is required, it may be applied to the soil, mixed in the fertilizer at rates supplying 4-14
kg/ha (3.5-12.5 lb/acre). The higher rate should be sufficient for up to three years. Not more than
4 kg/ha (3.5 lb/acre) should be banded at planting. Zinc may be applied as a foliar spray at rates
supplying 60 g/100 L (0.6 lb/100 gal). A wetting agent should be added. Spray to leaf wetness.

Tissue testing can be used to determine the zinc status of plants. Assuming critical levels are available
for interpretation or sample good and bad areas separately for direct comparison of values. Often a
foliar application is used if the values indicate a need to supplement. Since micronutrients are needed
in small amounts, foliar applications can often deliver a sufficient quantity to the right plant part (the
newest growth) where deficiencies are most pronounced.

Timing of Application
Timing of zinc is thought to be better in the early season as often the deficiencies can be seen as
early as three to five leaf corn. Placing Zn in a starter band close to the developing roots will aid in
early season uptake. Zn uptake is lower in high pH soils. Placing Zn in an acidifying band with P will
enhance Zn availability.

138 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Method of Application
As stated earlier, zinc can be either soil applied or foliar. With a proactive soil testing program and
field nutrient plans, the need for zinc can be addressed early in the crop rotation and amended with
soil applications. Foliar applications are best suited as a rescue treatment or used when unusual
circumstances require additional applications.

Performance Objective 16
Discuss considerations to determine the proper rate, timing and placement of
manganese (Mn) based on the:

a. crop type;
b. cropping system;
c. crop growth stage;
d. soil test or tissue test;
e. timing of application;
f. method of application.

Crop Type
Similar to zinc, using Table 4.11 the demand for Mn by crop can be determined. Soybeans and
wheat are two crops with high requirements for Mn as are most of the vegetable crops especially in
muck soils. Rates of application can be based on a soil test. Usually, soil test recommendations will be
based on a salt formulation. Divide that by eight to obtain a foliar rate. There are many foliar products
available, choose the ones with the appropriate content. Many are multi-nutrient offering a shotgun
approach to foliar nutrition, others are more single element based. Follow manufacturer’s labelled
recommendations.

Cropping System
Regardless of cropping system, soil applied Mn is not the most efficient method of application. The
major process involved in Mn availability in the soil is oxidation reduction reactions. This process can
limit plant availability, increasing when it is wet and decreasing when it is dry. Soil applications can be
made but require higher rates and should be band applied in a starter fertilizer such as MAP to limit
soil contact and be in the acidifying environment to keep availability high.

Crop Growth Stage
Early season applications are thought to be best. If soil applying, place in bands rather than broadcast.
Most likely, a foliar application is best and may have to be repeated as new growth appears.
Insufficient leaf surface area may limit the amount of Mn taken up early in the growth stages. Soybeans
may need more than one spray as deficiencies can appear based on weather conditions throughout the
vegetative stages.

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 139

Soil Test and Tissue Test
There is an accredited test for Mn using the phosphoric acid extraction methodology. Soil test values
are expressed as an index modified by soil pH with the critical value based on 16. Table 4.13 offers
an interpretation.

Tissue tests can also be used to determine nutritional status. Most labs will offer an interpretation based
on a critical level. Follow lab protocols for sample submissions.

Table 4.13 Manganese Soil Test Interpretation

Manganese Index1 Suggested Treatments

greater than 30 Soil manganese availability is adequate for field-grown crops.

16 to 30 Soil manganese availability is adequate for many crops but is approaching deficiency levels for oat,
barley, wheat and soybeans. If deficiency symptoms appear, spray with manganese. Consider a re-
check for deficiency using plant analysis.

below 16 Soil manganese availability is believed to be insufficient for oat, barley, wheat and soybeans. Spray
with manganese at the 4-leaf stage and again 3 weeks later if required. Manganese deficiency has
not been diagnosed on corn in Ontario, even on soils that are very deficient for wheat.

1. These values are indices of manganese availability based on extractable soil manganese and soil pH.

Chart source: Agronomy Guide for Field Crops, Publication 811, OMAFRA, 2009, p. 161.

Table 4.14 Manganese Requirements Vegetable Crops

Manganese Index1 Manganese (Mn) Required2 - kg/ha

Onions, Lettuce, Beets Other Vegetable Crops

0-7 2 03

8-15 2 0

16-49 0 0

50+ Above Normal 0 0

1. Manganese Index = 498 + 0.248 (phosphoric acid extractable Mn in mg/L of soil) - 137 (soil pH) + 9.64 (soil pH)2
2. Manganese should be applied as foliar spray of manganese sulphate. Soil applications are inefficient.
3. T he manganese soil test is low, however manganese deficiency is not expected on this crop. If deficiency symptoms appear, make a foliar application of 2 kg Mn/ha in 200 L

water (1.8 lb Mn/acre in 18 gal water).

Source: Micronutrients, Specialty Crop Opportunities, http://www.omafra.gov.on.ca/CropOp/en/general_agronomics/nutrient_management/micronutrients.html#manganese, accessed
April 4, 2016.

Timing of Application
See explanation under cropping system and crop growth stage.

Method of Application
See explanation under cropping system and crop growth stage.

140 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Performance Objective 17
Discuss considerations to determine the proper rate, timing and
placement of boron (B) based on the:

a. crop type;
b. cropping system;
c. crop growth stage;
d. soil test or tissue test;
e. timing of application;
f. method of application.

Crop Type
From Table 4.11, choose the crops with high demand for boron (B). Alfalfa, broccoli and cauliflower
stand out as needing B. Canola is not in the table but current research is suggesting response to foliar
B. Foliar B applications on canola can help reduce the negative impacts of high temperature during
flowering. On alfalfa, a deficiency can usually be corrected or prevented by an application of 1.0-2.0
kg/ha of boron broadcast annually. Boron should not be banded at seeding. Boron application on
crops that have not demonstrated a need may actually cause yield declines.

Cropping System
Depending on the crop rotation, the need for B will be determined. Alfalfa has a high demand and
would most likely require supplemental B especially on higher pH coarse-textured soils. Care must
be taken not to over apply B and have carryover to sensitive crops following the alfalfa. Careful field
nutrient planning would account for nutrient needs ahead of time and formulate an application strategy.
B on alfalfa may be best applied in the spring before dormancy breaks or just after the first cut.

Crop Growth Stage
Boron is initially involved in root elongation early in the season and then becomes a sugar mover. It
is involved in cell wall structures and reproduction processes later in the season. A continuous supply
throughout the season, especially on vegetables, usually means multiple smaller rates of applications to
meet metabolic requirements.

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 141

Soil Test and Tissue Test
Currently, there is no accredited soil test but labs do offer a hot water extractable methodology.
Interpretation is lacking. If applying foliar, follow manufacturer’s recommendations. For alfalfa B
application see comment under crop type above. Tissue tests are available and will interpret nutrient
status based on critical levels. See Table 4.15, any values below 20 ppm on alfalfa for B would
indicate a deficiency.

Table 4.15 Interpretation of Plant Analysis for Alfalfa

Nutrient Units Critical Concentration1 Maximum Normal
Concentration2
Nitrogen (N) % - 5.5
0.20 0.5
Phosphorus (P) % 1.70 3.5
4.0
Potassium (K) % - 1.0
0.20 -
Calcium (Ca) % 0.22 90.0
20.0 30.0
Magnesium (Mg) % 5.0 100.0
20.0 5.0
Sulphur (S) % 0.5 70.0
10.0
Boron (B) ppm

Copper (Cu) ppm

Manganese (Mn) ppm

Molybdenum (Mo) ppm

Zinc (Zn) ppm

Chart source: Agronomy Guide for Field Crops, Publication 811, OMAFRA, 2009, p. 68.

Timing of Application
Boron is very soluble and mobile in the soil. Early season broadcast on alfalfa with dry granular B
mixed in potash is common and an acceptable practice. Foliar B on alfalfa has limited value as the
rates required are too high and the risk of foliar burn limits its appeal (no point in burning the foliage
that is needed for feed value). In vegetable crops, a combination of soil applied and foliar at critical
developmental stages is practiced by most growers. In apple trees, pre- or post-bloom spray, based on
tissue test critical levels, suggest a rate of 200 g/ha of actual B.

Method of Application
Banding or seed row placed boron can be toxic to plants and is not recommended. In alfalfa, the
recommendation to correct a boron deficiency is to broadcast 1 – 2 kg/ha of actual boron, applied
annually. The benefit of broadcast and incorporated B in canola has not been tested in Ontario. If B is
to be applied foliar in canola, the recommended rate is 0.3 – 0.5 lb/ac (0.34-0.56 kg/ha) of actual
boron. Many other field crops have low B requirements and can be injured by B applications. Most
notable are the grass family, dry beans, cereals, soybeans, corn, and peas. If these crops are to follow
in the rotation, do not apply boron the previous fall, or exceed the recommended rate in the previous
alfalfa or canola crop.

142 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Competency Area 7
Determining the Right Rate, Timing and Placement
of Lime for pH adjustment

Performance Objective 18
Discuss considerations to determine the proper rate, timing and placement of
agricultural lime based on:

a. target pH by crop;
b. soil test pH and buffer pH, and magnesium;
c. timing of application;
d. method of application;
e. sources of lime;
f. major nutrient contribution from lime.

Soil pH is one of the most important nutrient parameters in crop production. Soil pH controls the
availability of essential nutrients by influencing water solubility and therefore plant availability of
nutrients. Soil pH also influences many biological activities involved in nutrient cycling.
Choosing the rate of limestone involves determining the target pH, using the BpH to determine lime
rate, looking at the Mg soil test to determine type of lime, and making an application that is most
effective in both timing, cropping system and depth of incorporation. And, finally, a rate adjustment
based on the Ag Index.

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 143

Table 4.16 Lime Requirements to Correct Soil Acidity Based on Soil pH and Soil Buffer pH

Buffer pH1 7.0 Target Soil pH 5.54
6.52 6.03
1 (0.5)
7.0 2 (0.9) 2 (0.9) 1 (0.5) 1 (0.5)
1 (0.5)
6.9 3 (1.3) 2 (0.9) 1 (0.5) 1 (0.5)
1 (0.5)
6.8 3 (1.3) 2 (0.9) 1 (0.5)
1 (0.5)
6.7 4 (1.8) 2 (0.9) 2 (0.9) 2 (0.9)
2 (0.9)
6.6 5 (2.2 3 (1.3) 2 (0.9) 2 (0.9)
2 (0.9)
6.5 6 (2.7) 3 (1.3) 2 (0.9)
3 (1.3)
6.4 7 (3.1) 4 (1.8) 3 (1.3) 4 (1.8)
4 (1.8)
6.3 8 (3.6) 5 (2.2) 3 (1.3) 5 (2.2)
6 (2.7)
6.2 10 (4.5) 6 (2.7) 4 (1.8)
8 (3.6)
6.1 11 (4.9) 7 (3.1) 5 (2.2) 9 (4.0)
10 (4.5)
6.0 13 (5.8) 9 (4.0) 6 (2.7) 11 (4.9)
13 (5.8)
5.9 14 (6.2) 10 (4.5) 7 (3.1)
15 (6.7)
5.8 16 (7.1) 12 (5.4) 8 (3.6) 16 (7.1)
18 (8.0)
5.7 18 (8.0) 13 (5.8) 9 (4.0) 20 (8.9)
20 (8.9)
5.6 20 (8.9) 15 (6.7) 11 (4.9)

5.5 20 (8.9) 17 (7.6) 12 (5.4)

5.4 20 (8.9) 19 (8.5) 14 (6.2)

5.3 20 (8.9) 20 (8.9) 15 (6.7)

5.2 20 (8.9) 20 (8.9) 17 (7.6)

5.1 20 (8.9) 20 (8.9) 19 (8.5)

5.0 20 (8.9) 20 (8.9) 20 (8.9)

4.9 20 (8.9) 20 (8.9) 20 (8.9)

4.8 20 (8.9) 20 (8.9) 20 (8.9)

4.7 20 (8.9) 20 (8.9) 20 (8.9)

4.6 20 (8.9) 20 (8.9) 20 (8.9)

Chart source: Agronomy Guide for Field Crops, Publication 811, OMAFRA, 2009, p. 159.

144 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Target pH by Crop
Different crops have optimum pH ranges in which they grow best. These have been established for
agronomically important crops in Ontario see Table 4.17 for ranges

Table 4.17 Soil pH at Which Lime is Recommended for Ontario Crops

Crops Soil pH Below Which Target Soil pH1
Lime is Recommended

Coarse and medium-textured mineral soils (sand, sandy loams, loams and silt loams)

Perennial legumes, oat, barley, wheat, triticale, beans, peas, canola, flax, 6.1 6.5
tomatoes, raspberries, strawberries, all other crops not listed below

Corn, soybeans, rye, grass, hay, pasture, tobacco 5.6 6.0

Potatoes 5.1 5.5

Fine-textured mineral soils (clays and clay loams)

Alfalfa, cole crops, rutabagas 6.1 6.5

Other perennial legumes, oat, barley, wheat, triticale, soybeans, beans, 5.6 6.0
peas, canola, flax, tomatoes, raspberries, all other crops not listed above
or below

Corn, rye, grass hay, pasture 5.1 5.5

Organic soils (peats and mucks)

All field and vegetable crops 5.1 5.5

1. W here a crop is grown in rotation with other crops requiring a higher pH (for example, corn in rotation with wheat or alfalfa), lime the soil to the higher pH.

Chart source: Agronomy Guide for Field Crops, Publication 811, OMAFRA, 2009, p. 158.

Soil Test pH and Buffer pH
Soil pH controls the availability of essential nutrients. The flowing graphic illustrates the range of
availability influenced by the pH. The area of each nutrient in the bar graph at its widest point is the
area of maximum availability.

Source: Spectrum Analytic, http://www.spectrumanalytic.com/doc/library/articles/soil_buffer_ph, accessed April 21, 2016

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 145

As an example, in phosphorus we can see from the graph the bar narrows at pH below 6.5 and again
at pH 7.5. The ideal pH for all nutrients is 6.8 as a vertical line from 6.8 will intersect most nutrients at
the widest part of the bar graph.

Muck soils will tend to have optimum nutrient availability at pH 5.5. These soils exhibit very high CEC
and can hold high amounts of exchangeable cations, mainly calcium, and still be 50% saturated with
hydrogen. Muck soils are derived from decaying plant matter with organic matter usually greater than
50%. They lack the mineral content that can provide aluminum, one of the major contributors to soil
acidity that increases phyto-toxicity to roots. As a result, vegetable crops can grow under lower pH and
still find ample calcium and experience no deleterious effects of aluminum. Seldom is there a need to
lime muck soils.

Soil pH measures active acidity whereas Buffer pH measures reserve acidity. Both values are
determined by a lab test. Magnesium soil value is used to determine which kind of limestone to use.
Two types of limestone are available in Ontario; dolomitic which contains Mg as well as Ca and
calcitic lime that contains predominately calcium. Dolomitic is chosen when the soil test is below 100
ppm to supply additional Mg. This is often the most cost effective way to increase soil test Mg and
reduce acidity

Timing of Application
Timing of application is often determined by the most sensitive crop in the rotation, the limestone quality
or Ag Index, and the time needed to make an effective pH change. Usually a fall application is done
when there is more time for that task. After winter wheat harvest is usually an effective time to sample
and apply limestone. Soil testing can be done with ample time to allow turnaround time from soil test
lab, view results, make a field nutrient plan, source the appropriate lime and apply.

Method of Application
For lime to be effective, it needs to be broadcast applied and thoroughly incorporated into the bulk
of the soil so the reaction can take place to neutralize the acidity. This often means plowing and
incorporating into the root zone. In no till, this may require a one-time tillage operation. Applying half
the rate twice as often has been another practice that producers have adopted in no till or minimum till
systems. It may mean a slower rate of reaction or in some cases near surface acidity is all that needs to
be corrected. Banding of limestone is not effective.

146 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

Sources of Lime
There are two main sources of limestone, calcitic and dolomitic. They can vary in quality. To evaluate
quality, an Ag Index is used to provide a combined measure of neutralizing value and fineness rating
into one value. The final adjustments to recommended rates are made with the Ag Index. Most labs
assume an Ag Index 75 lime will be used when offering a limestone recommendation. Based on
lime source and quality, an adjustment to the final recommended rate may be required to account for
neutralizing differences in sources.

There are other source materials that can be used such as wood ash and other industrial by-products
or other mineral deposits. They do need a lab test to determine neutralizing value to allow for rate
adjustments with an Ag Index. These materials may contain other nutrients and sometimes undesirable
heavy metals. When a non-traditional material comes to market, always perform a lab test. Note that
gypsum is an ineffective lime source; it has no neutralizing value but can supply calcium and sulphur.

Table 4.18 Calcium Sources

Formula Neutralizing value relative to calcium carbonate
100
Calcitic lime (calcium carbonate) CaCO3 119
Magnesium carbonate MgCO3 109
CaMg(CO3)2 135
Dolomitic lime (calcium magnesium carbonate) Ca(OH)2 179
Calcium hydroxide 172
Calcium oxide CaO 250
90
Magnesium hydroxide Mg(OH)2 0
Magnesium oxide MgO 40-80

Potassium hydroxide KOH

Gypsum (Calcium sulphate) CaSO4•2H2O
Wood Ashes n/a

Chart source: Soil Fertility Handbook, Publication 611, OMAFRA, 2006, p. 89.

Table 4.19 Example Calculation of Fineness Rating of a Limestone

Particle Size % of Sample Fineness Factor
x0
Coarser than No.10 sieve1 10 x 0.4 =0
x 1.0 = 16
No.10 to No. 60 sieve2 40 = 50
= 66
Passing through No. 60 sieve 50

Fineness Rating

1. A #10 Tyler sieve has wires spaced 2.0 mm apart.
2. A #60 Tyler sieve has wires spaced 0.25 mm apart.

Chart source: Agronomy Guide for Field Crops, Publication 811, OMAFRA, 2009, p. 159.

PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients 147

The Agricultural Index
This index has been developed in Ontario as a means of combining the neutralizing value and the
fineness rating to compare various limestones that are available.

The Agricultural Index = (neutralizing value x fineness rating) ÷ 100

The Agricultural Index can be used to compare the relative value of different limestones for
neutralization of soil acidity. Lime with a high Agricultural Index is worth proportionately more than lime
with a low index because it may be applied at a lower rate.

For example, if two ground limestones, A and B, have Agricultural Indices of 50 and 80 respectively,
the rate of application of limestone A required for a particular soil will be 80/50 x the rate required for
limestone B. Limestone A spread on your farm is worth 50/80 x the price of limestone B per tonne.

Recommendations from the OMAFRA soil test service are based on limestone with an Agricultural Index
of 75. If the Agricultural Index is known, a rate of application specifically for limestone of that quality
can be calculated. This can be done using the following equation:

Limestone application rate from soil text x (75 ÷ Agricultural Index of Limestone) = Rate of Application
of Limestone

For example, if there is a limestone requirement by soil test of 9 t/ha, and the most suitable source of
limestone from a quality and price standpoint has an Agricultural Index of 90, then apply 7.5 t/ha
(75/90 x 9).

The Agricultural Index does not provide information about magnesium content. Dolomitic limestone
should be used on soils low in magnesium.

Tillage Depth
Lime recommendations presented here should raise the pH of the top 15 cm (6 in) of a soil to the listed
target pH. If the soil is plowed to a lesser or greater depth than 15 cm, proportionately more or less
lime is required to reach the same target pH. Where reduced tillage depths are used, reduce rates of
application proportionately. More frequent liming will be needed

Major Nutrient Contribution from Lime
The two main nutrients that come from lime are calcium from calcitic limestone and calcium and
magnesium in dolomitic lime. These nutrients are readily available from lime when it reacts in acidic
conditions. Limestone reacts in the presence of hydrogen ions. The accompanying carbonates or
hydroxyl ions do the work of neutralizing acidity by removing H ions and then the calcium and
magnesium can re-saturate the exchange complex.

Calcitic lime usually contains calcium in the range of 35% to 39%; there may be up to 2% of Mg in
some sources.

Dolomitic lime can contain Ca in a range of 19% to 21% and Mg from 9% to 13%.

148 PROFICIENCY AREA IV - Potassium, Secondary Macronutrients and Micronutrients

PROFICIENCY AREA V

MANURE
MANAGEMENT

Competency Area 1
Whole-Herd or Whole-Flock Total Annual
Manure and Nutrient Production

Performance Objective 1
Calculate the total number of nutrient units in an operation.

In Regulation 267/03 under the Nutrient Management Act, 2002, a nutrient unit is defined as “the
amount of nutrients that give the fertilizer replacement value of the lower of 43 kg of nitrogen or 55 kg
of phosphate as nutrient as established by reference to the Nutrient Management Protocol”. Nutrient
units are calculated by looking at Table 1 in the Nutrient Management Tables. It lists various species
and sizes of animals, and the number of each it takes to generate one NU. The complete tables can
be found at http://www.omafra.gov.on.ca/english/nm/regs/nmpro/nmtab01-15.htm. If the farm unit
has more than one type of farm animal present on it then this calculation would have to be completed
for each type of animal separately, then all the results totaled to give the total NU generated by farm
animals on the farm.

Below are two excerpts from Table 1 from the Nutrient Management Tables, mentioned in the above
paragraph, as examples.

Table 5.1. Excerpts from Table 1 in the Nutrient Management Tables

Beef - Backgrounders (7 - 12.5 months)

Sub Ave. Weight Utilization Liquid Amt Liquid Solid Amt Solid Nutrient Livestock
Sub-Type (kg) (%) (m3 1000 DM* (m3 1000 DM* Units Housing
kg/day) (%) kg/day) (%) Capacity
(animal/NU) (m2 animal)

Confinement 308 90 0.0724 9.0 0.0604 22 3 4.65

Yard/Barn 308 90 0.0604 22 3 3.72

Horses – Medium Frame (including unweaned offspring)

Sub Ave. Weight Utilization Liquid Amt Liquid Solid Amt Solid Nutrient Livestock
Sub-Type (kg) (%) (m3 1000 DM* (m3 1000 DM* Units Housing
kg/day) (%) kg/day) (%) Capacity
Box Stalls 454 (animal/NU) (m2 animal)
100 9 0.0887 46
1 23.2

PROFICIENCY AREA V - Manure Management 149

Calculation example for a farm with 120 beef backgrounders and 10 horses:

Livestock Nutrient unit conversion factor Nutrient Units
(from Table 1 in the NM Tables)
120 beef backgrounders 40
10 medium frame horses 3 10
50
Total Nutrient Units 1

Performance Objective 2
Distinguish the difference between animal units and nutrient units.

As noted in the Performance Objective above, a nutrient unit is defined under the Nutrient Management
Act 2002 as “the amount of nutrients that give the fertilizer replacement value of the lower of 43 kg
of nitrogen or 55 kg of phosphate as nutrient as established by reference to the Nutrient Management
Protocol”.

In other jurisdictions, including the U.S., they use the term “animal unit” when conducting nutrient
management plans. The animal unit factor is determined by dividing the average mature animal weight
by 1,000, so one AU is the equivalent of 1,000 pounds animal live weight. Individual regulations and
legislation will have prepared tables listing the standard unit of measurement for typical animal feeding
operations. Below is an example from the Illinois Livestock Management Facilities Act:

Sec.10.10. “Animal unit” means a unit of measurement for any animal feeding operation calculated
as follows:

1. Brood cows and slaughter and feeder cattle multiplied by 1.0.
2. Milking dairy cows multiplied by 1.4.
3. Young dairy stock multiplied by 0.6.
4. Swine weighing over 55 pounds multiplied by 0.4.
5. Swine weighing under 55 pounds multiplied by 0.03.
6. Sheep, lambs, or goats multiplied by 0.1.
7. Horses multiplied by 2.0.
8. Turkeys multiplied by 0.02.
9. Laying hens or broilers multiplied by 0.01 (if the facility has continuous

overflow watering).
10. Laying hens or broilers multiplied by 0.03 (if the facility has a liquid manure

handling system).
11. Ducks multiplied by 0.02.

150 PROFICIENCY AREA V - Manure Management