Performing estimation and basic calculation

TECHNICAL EDUCATION AND SKILLS DEVELOPMENT AUTHORITY
QUEZON NATIONAL AGRICULTURAL SCHOOL

Web Script for Agricultural Crop Production NC III

Objectives PERFORM ESTIMATION AND BASIC CALCULATION
Introduction
LESSON 1 At the end of this unit, you should be able to:
1. perform basic workplace calculation
TOPIC 1
2.

Calculation
Calculation - the procedure of calculating; determining something by mathematical or logical
methods computation, computing transposition - (mathematics) the transfer of a quantity from
one side of an equation to the other along with a change of sign number crunching - performing
complex and lengthy numerical calculations
Quantity of Feeds on Swine Production

PIG FOOD REQUIREMENTS
A pig’s food and water requirements change as pigs grow.

Piglets (Under 40 lbs.)
Piglets, younger pigs that weigh less than 40 pounds,
should be introduced to a solid diet through creep
feeding while they are still suckling. Dietary needs will
increase daily with a pig’s weight.

Growing & Finishing Pigs (40+ lbs.)
Growing pigs, those weighing 40 to 125 pounds, and
finishing pigs, those weighing 125 pounds to market weight (approximately 230 pounds or
more) should transition from the grower feeds that are nutrient dense with more protein to
the finisher feeds that are less dense.

Expected Pig Growth Rates
Because a pig eats approximately 4% of its body weight per day, they require a number of
essential nutrients to meet their daily needs, i.e., water, carbohydrates, fats, protein (amino
acids), minerals, and vitamins. With a proper diet, expect weight gains of about 1.5 to 1.7
pounds per day up to approximately 110 pounds. After that, weight gains of 1.8 to 2.2
pounds per day.

How much to feed pigs

As a rule of thumb, you feed 1lb (450g) of food each day for each month of age, up to a
maximum of 6lbs (2.75kg) per day. Do not feed more than this - you will waste money and
end up with over-fat pigs. Only lactating sows need more food than this. Furthermore, weigh
the food. Six pounds is probably less than you think.

E-Learning for Agricultural Crop Date Developed: Version No. 1
Production NC III May 2020
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Module Title: Developed by:
Performing Estimation and Basic ROBERT R. SITJAR

Calculation

TECHNICAL EDUCATION AND SKILLS DEVELOPMENT AUTHORITY
QUEZON NATIONAL AGRICULTURAL SCHOOL

As a second rule of thumb, all feed should be cleared up within 20-30 minutes – if not,
reduce the amount then increase gradually as appetite increases. On average, taking a
weaner from 8 weeks to slaughter six and a half months later will use about 380kg of feed
(19 x 20kg bags).

On our Pig Paradise course, there was a couple that had successfully raised two
Saddleback weaners and were about to get their second pair. When we were shown how
much six pounds of feed was, they were aghast and said that they had been feeding this
amount twice per day. They also admitted that their pigs had killed out with about six inches
of back fat!

Split the feeds into at least two per day. Pigs like feeding so give them as much fun as
possible. If it is very wet underfoot, you may have to use a trough but if it is reasonably dry,
scattering the pellets on the ground makes feed-time last longer. If you are using a trough,
make sure there is enough space for all the pigs to feed in comfort.

Supplementing feed with fresh produce

You can supplement the bagged feed with fruit and vegetables but be aware that it is illegal
to feed them any catering waste i.e. any food that has been in any kitchen, whether

domestic or commercial.

If you are feeding large quantities of fruit and vegetables,
reduce the amount of bagged feed on a 1:4 ratio i.e. if
you feed 4kg of bananas, reduce the bagged feed by
1kg.

TOPIC 2 Amount of Fertilizer

The amount of fertilizer needed per acre is dependent upon many factors,
including the type of plant being fertilized. In addition, the amount of nitrogen in
the ground must be considered before applying fertilizer.

According to the UGA Center for Urban Agriculture, grass needs a pound of

fertilizer per every 1000 feet. Hay, however, requires 40 to 60 pounds of fertilizer

per acre. According to the University of Arkansas, most food plots require about

E-Learning for Agricultural Crop Date Developed: Version No. 1
Production NC III May 2020

Module Title: Developed by: Page 2 of 8
Performing Estimation and Basic ROBERT R. SITJAR

Calculation

TECHNICAL EDUCATION AND SKILLS DEVELOPMENT AUTHORITY
QUEZON NATIONAL AGRICULTURAL SCHOOL

50 pounds of fertilizer per acre.

Determining how many bags of fertilizer to use is dependent upon how much
nitrogen is in each bag of fertilizer. To calculate this amount, take the amount of
nitrogen required per 1000 feet and divide it by the amount of nitrogen contained
in a single bag of fertilizer.

Understand how much nutrients (NPK) the crop needs to produce a ton of
grain per hectare and translate that amount to what you have to apply on the
field.

N, P and K are the most needed nutrients in rice

Nitrogen (N) promotes rapid plant
growth and improves grain yield and
grain quality. N is generally the most
limiting nutrient as it is needed in large
amounts and is readily lost as a gas
(volatilized) and by leaching (washing
out of the root zone).

Nitrogen deficiency is the most common nutrient
problem. The plants give a lower yield due to
limited photosynthesis and assimilation.

Phosphorus (P) is essential for root
development, tillering, early flowering,
and ripening. It is especially deficient
in sandy soils with low organic matter
contents, in very acid soils and in
alkaline soils.

P deficient plants are stunted, tillering is reduced,
the leaves often have a blackish green color, and

maturity is delayed.

E-Learning for Agricultural Crop Date Developed: Version No. 1
Production NC III May 2020
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Module Title: Developed by:
Performing Estimation and Basic ROBERT R. SITJAR

Calculation

TECHNICAL EDUCATION AND SKILLS DEVELOPMENT AUTHORITY
QUEZON NATIONAL AGRICULTURAL SCHOOL

Potassium (K) is essential for root
growth and plant vigor. It also helps
against lodging and improves the crop
resistance to diseases. Potassium can
quickly become yield limiting in high
yielding rice systems where most of
the straw is removed because rice
straw is rich in K!

K deficient plants are stunted dark green plants
with yellowish brown leaf margins older leaves can

have necrotic tips and margins, and lodging is
more frequent.

Zinc and sometimes sulfur deficiencies are much less frequent but can be important
locally.

Nitrogen, phosphorous and potassium make the rice plant strong and healthy with
many tillers which result in a high yield.

The different benefits of N, P and K to the rice plant

How much nutrients does the crop need?

In the previous lessons we explained that the crop needs nutrients to grow and mature
normally.
The rice crop needs the following uptake of N, P and K to produce 1 ton of grain per
hectare:

• Nitrogen (N):15-20 kg

• Phosphorous (P): 2-3 kg

• Potassium (K): 15-20 kg (If all straw remains in the field and is evenly
distributed, K requirements can be reduced to 3-5 kg/ha per ton of grain yield.

E-Learning for Agricultural Crop Date Developed: Version No. 1
Production NC III May 2020
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Module Title: Developed by:
Performing Estimation and Basic ROBERT R. SITJAR

Calculation

TECHNICAL EDUCATION AND SKILLS DEVELOPMENT AUTHORITY
QUEZON NATIONAL AGRICULTURAL SCHOOL

Fertilizer Application

In every field, you will get a certain grain yield even if you don�t apply any fertilizer.
The nutrients for this yield are supplied by the soil. If you want to increase the yield, it
is necessary to apply fertilizers.

However, it is very important to understand that of all the fertilizer you apply on the
field, the crop can only take up a fraction.

For nitrogen, for example, even with good management about half the applied
fertilizer (50%) is lost. We said above that the plants need to take up 15 to 20 kg of
nitrogen per hectare to produce 1 ton of grain. This means we have to apply twice as
much fertilizer, or 30 to 40 kg of N per hectare, to produce an extra ton of grain!

So, imagine:

Notes:

o This example uses 15kg as needed N uptake. The needed N crop uptake ranges from 15 to 20 kg N

per ton of grain/hectare.

o These calculations assume nitrogen is the major factor limiting yields.

E-Learning for Agricultural Crop Date Developed: Version No. 1
Production NC III May 2020
Page 5 of 8
Module Title: Developed by:
Performing Estimation and Basic ROBERT R. SITJAR

Calculation

TECHNICAL EDUCATION AND SKILLS DEVELOPMENT AUTHORITY
QUEZON NATIONAL AGRICULTURAL SCHOOL

LESSON 2 Estimating Crop Yields
A simple method to estimate the yield of a range of field crops for use by farmers and
agribusiness is outlined.

Introduction

Accurate, early estimation of grain yield is an important skill. Farmers require accurate yield
estimates for a number of reasons:

• Crop insurance purposes
• Delivery estimates
• Planning harvest and storage requirements
• Cash-flow budgeting

Extensive personal experience is essential for estimating yield at early stages of growth. As
crops near maturity, it becomes easier to estimate yield with greater accuracy.

Estimation methods

There are many methods available for farmers and others to estimate yield of various crops.
Some are straightforward whereas others are more complicated. The method presented in
this article is one that can be undertaken relatively quickly and easily Steps are as follows:

1. Select an area that is representative of the paddock. Using some type of measuring
rod/tape, measure out an area 1 meter square and count the number of heads/pods.

2. Do this 5 times to get an average of the crop.

3. Count the number of grains in at least 20 heads/pods and average.

4. Using Table 1 below determine the grain weight for the crop concerned and follow through
the calculation outlined below

Accuracy of yield estimates depends upon an adequate number of counts being taken so as
to get a representative average of the paddock. The yield estimate determined will only be a
guide and assumptions made from the estimates contain a degree of uncertainty.

This type of yield estimation is one of the easiest and quickest to complete and should be
able to be used in a number of situations on a grain growing property. Grain losses both
before and during harvest can be significant and an allowance for 5-10 per cent loss should
be included in your final calculations.

E-Learning for Agricultural Crop Date Developed: Version No. 1
Production NC III May 2020
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Module Title: Developed by:
Performing Estimation and Basic ROBERT R. SITJAR

Calculation

TECHNICAL EDUCATION AND SKILLS DEVELOPMENT AUTHORITY
QUEZON NATIONAL AGRICULTURAL SCHOOL

Table 1: Grain weights expressed as weight per 100 grains.

Crop type Weight of 100 grains (in grams)
Canola 0.4
Wheat 3.4
Lentils 3.0-5.0
Safflower 3.8
Oats & triticale 4
Barley 4.2
Lupin (narrow leaf) 16
Chickpea (desi) 18
Field pea 20
Lupin (broad leaf) 30
Chickpea(kabuli) 40
Faba bean 50

Methodology for estimating wheat yield

Number of heads/pods per square meter (A) Example 220

Average number of grains per head/pod (B) Example 24

Number of grains per square metre = AxB (C) Example = 220 x 24 = 5280

Yield per square meter = C/100 x 3.4gms (D) Example = 5280/100 x 3.4 = 179.52gms

Yield in t/ha = D/100 Example = 179.52/100 = 1.79t/ha

The same method can be used for any other grain crop as long as you choose the correct
seed weight from Table 1.
The basis behind this method for estimating yields is the counting of heads or pods per
square meter.

http://agriculture.vic.gov.au/agriculture/grains-and-other-crops/crop-production/estimating-crop-
yields-a-brief-guide

E-Learning for Agricultural Crop Date Developed: Version No. 1
Production NC III May 2020
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Module Title: Developed by:
Performing Estimation and Basic ROBERT R. SITJAR

Calculation

TECHNICAL EDUCATION AND SKILLS DEVELOPMENT AUTHORITY
QUEZON NATIONAL AGRICULTURAL SCHOOL

ACP3 Ref.

https://search.yahoo.com/search?fr=mcafee&type=E211US885G0&p=calculation
https://osbornelivestockequipment.com/2018/09/pig-feeding-guide/
https://www.accidentalsmallholder.net/livestock/pigs/feeding-pigs/
https://www.reference.com/world-view/much-fertilizer-should-used-per-acre-fbd2dab97a1ff87b
http://www.knowledgebank.irri.org/ericeproduction/IV.3_Nutrient_calculator.htm
http://agriculture.vic.gov.au/agriculture/grains-and-other-crops/crop-production/estimating-crop-yields-a-brief-
guide

E-Learning for Agricultural Crop Date Developed: Version No. 1
Production NC III May 2020
Page 8 of 8
Module Title: Developed by:
Performing Estimation and Basic ROBERT R. SITJAR

Calculation