Basics of Crop Production
Soil and Plant Fertility
Soil Quality
• This is the most important factor in
farm crop production.
• Soils will determine which plant species
yields the most, the time of harvest, and
ultimately the investment a landowner
must make to yield an acceptable
economic return from management.
Soil Profile
The soil profile
shows the layers,
known as horizons
that represent
the soil.
Horizons formed
over the centuries
due mostly form
weathering.
A lettering system
is used to name
the different
horizons.
Where can you find info
on a farm’s soil?
• In the County Soil Survey Map.
• There are Tables on several land
options such as Woodland Management
and Productivity which provides a lot
of valuable information on the potential
for soil erosion, seedling mortality,
species preference, and tree growth.
County Soils Map
There is even a table in the Soil Survey
Map that evaluates sites for wildlife
habitat.
Factors Controlling Plant
Growth
• Light
• Mechanical Support
• Heat
• Air
• Water
• Nutrients
• All except for light, involves soil
Major Components of Soil
Air
Water
Organ. Matter
Mineral
50%
Soil Terminology
• Soil texture
- concerns the size of mineral
particles, specifically the
relative proportion of various
size groups in a given soil
• Soil structure
- the arrangement of soil particles
into groups of aggregates
Soil Texture
• Soil texture is separated into three soil
separates based on particle size.
1 Sand
2 Silt
3 Clay
Soil Texture
• Silt, clay
- imparts a fine texture and slow
water and air movement, also high
water holding capacity
• Sandy to gravelly
- are referred to as lighter soils with
lower water holding capacity
Soil Texture
• Sandy soils are normally very well
drained and often lack nutrients due to
constant leaching loss.
• Mostly clay soils are at the opposite end
of the soil spectrum. They tend to allow
water to move through more slowly
and will stay wetter longer. They will
hold nutrients.
Soil Terminology
• Pore space
- is that portion of the soil occupied
by air and water
- sandy soils have low soil porosity,
while silt and clay soils have high
soil porosity
• Soil compaction
- fine textured, wet soils are more
easily compacted
- compaction reduces pore spaces
Soil Terminology
• Soil depth
- defined as that depth of soil material
favorable for plant root penetration
- deep, well drained soils are the best
Soil Terminology
• Slope
- land topography largely
determines the amount of
drainage, runoff, and erosion
- the steeper the land, the more
management is required
Soil Terminology
• Organic matter
- it consists of plant and animal
residues in various stages of decay
- adequate levels benefit soil by:
1) improving physical condition
2) increasing water infiltration
3) improving soil tilth
4) decreasing erosion losses
5) supplying plant nutrients
6) holding cation nutrients
Soil Terminology
• pH
- expression of both acidity and
alkalinity on a scale whose values
run from 0 to 14 with 7 representing
neutrality, <7 represents acidity,
and >7 represents alkalinity
• pH has a significant impact on the
availability of soil nutrients
• pH 6.5
- pH objective for most ag crops
pH Scale
The figure shows
the break down
of where acidity
to alkalinity is on
the pH scale.
PH 7 is neutral.
pH Effect on Nutrient
Availability
This graphic shows
how the major plant
nutrients change in
availability with the
increase and
decrease of pH.
The wider the black
band in this
graphic, the more
available the
nutrient.
This has a direct
impact on plant
health. For most
agricultural crop
recommendations,
the goal is to have
a 6.5 pH. At this pH
most of the
essential plant
nutrients are
available.
pH Preferences by Plants
This graphic
shows the range in
pH preferred by
plants. This
shows that it is
important for
producers to know
the fertility and pH
requirements of
the plants they
plan to grow.
As can be seen
from the black
bands, most plants
prefer a pH
between 5.5 and
7.0.
A pH below 5.5 is
considered to be
very acid and
above 7.0 is
alkaline.
.
Limiting Factors
Root
• A layer which restricts the downward
penetration of a plant’s root system
will reduce growth in direct relation
to the depth of the layer.
• On rare occasions, a limiting layer may
increase site productivity, such as on
sandy soils where the layer may retard
leaching of nutrients and increase
available moisture.
Subsoiling
Subsoilers have long shanks that
physically dig down to break
open the hard soil to form
channels where plant roots can
penetrate.
There are farm implements
available that can breakup
soil hard pans and
improve the crop
production in otherwise
limited soils.
16 Essential Elements (part 1)
• Primary
Nitrogen (N)
Phosphorus (P)
Potassium (K)
• Secondary
Sulfur (S)
Magnesium (Mg)
Calcium (Ca)
The primary elements are plant nutrients that
are needed and most used by plants for
growth. The primary nutrients can be found
in commercial complete fertilizers as the
fertilizer number reflects these three
elements, i.e. 10-6-4.
Secondary elements are the next most
needed plant nutrients. Magnesium and
calcium are obtained from liming materials.
During the Industrial revolution, most of our
sulfur came from air pollution (sulfur
dioxide).
In recent years, producers have had to
routinely include supplemental sulfur to
their crop fertility programs as the air
around us becomes less contaminated with
sulfur.
16 Essential Elements (part 2)
• Micro-nutrients
Iron (Fe)
Manganese (Mn)
Boron (B)
Chlorine (Cl)
Zinc (Zn)
Copper (Cu)
Molybdenum (Mo)
16 Essential Elements (part 3)
• The final three (3) essential elements
to plant growth come mostly from air
and water.
• They are:
Carbon (C)
Hydrogen (H)
Oxygen (O)
The Primary Elements
• Nitrogen: It gives plants their green color,
promotes above ground growth, and
regulates utilization of other elements.
• Phosphorus: It has favorable affect on
- cell division
- stem strength
- crop maturation
- root development
- flowering/fruiting - disease resistance
The Primary Elements (con’t)
• Potassium (K)
- It is essential for starch formation
and translocation of sugars. It is
also essential to the development of
chlorophyll. K helps plants
to over-winter.
What is the nutrient content
of commercial fertilizers?
• Expressed as a percent called the
“guaranteed analysis” or fertilizer
grade.
• Nutrient content always appears in
this order:
% total nitrogen
% available phosphate (P2O5), or
phosphoric acid
% soluble potash (K2O)
The Fertilizer Number
The fertilizer number refers to a ratio of N-PK
5-10-5 (1-2-1 ratio) has:
5% N 10% P205 5% K20 = 20%
The other 80% of the material is called the
carrier. This is typically some inert material.
10 - 6 - 4 (2-1-1 ratio)
10 -10 -10 (1-1-1 ratio)
What does a fertilizer guarantee mean?
Ag-Gro-Pro
5-10-15
50 lbs.
This bag contains:
5% nitrogen--10% phosphate--15% potash
or
2.5 lbs. nitrogen
5 lbs. phosphate
7.5 lbs. potash
Common Fertilizers
•
•
•
•
•
•
•
Urea
Ammonium nitrate
UAN
Ammonium sulfate
Diammonium phosphate
Triple superphosphate
Muriate of potash
46 - 0 - 0
34 - 0 - 0
30 - 0 - 0
21 - 0 - 0
18 - 46 - 0
0 - 46 - 0
0 - 0 - 60
Determining Fertilizer Need
Production Goal: Total lb/A N - P - K
soil reserve
N –P - K
crop residue
N
manure
N-P-K
______________
Commercial fertilizer + lb/A N - P - K
Example: Calculating the Quantity of
Commercial Fertilizer Required to meet a
Nutrient Recommendation
Jasper Little Farm:
• needs 60 lbs./A of potash (K2O) on his
soybean crop
• broadcasts muriate of potash (0-0-60)
pre-plant
• see Example 4-1, p.18 in training guide
Calculating Quantity of
Commercial Fertilizer
1) RECORD recommended quantity of
nutrient (see nutrient management
plan).
60 lbs./A
2) RECORD the percentage of nutrient
in the preferred product, muriate of
potash.
60%
3) CONVERT the percentage of
nutrient to a decimal fraction by
multiplying the % by .01
60 x 0.01 = .60
Calculating the Quantity of
Commercial Fertilizer
CALCULATE the quantity of muriate of
potash required in lbs./A: divide the
recommended quantity of nutrient by
the nutrient content expressed as a
decimal fraction.
60 lbs./A ÷ 0.60 = 100 lbs./A
Little needs 100 lbs. of muriate of
potash to supply 60 lbs. of potash.
Done!
Determining Production
Goal
• Cropping history
• Soil Survey Map/Soil Capability Chart
• Investigate species/variety potential
- other growers
- field days
- private and university trial results
• FSA records
• Experimentation
Determining Yield Goal
• Take the average yield for typical
years that a crop is grown in a certain
field.
• Estimate yields goal by averaging the
yield from the best 3 of 5 growing
MASCAP
seasons.
• When actual yield data is not
available, estimated yields for the soil
type in the field can be found in
“MASCAP”.
MARYLAND’S
AGRONOMIC SOIL
CAPABILITY
ASSESSMENT
PROGRAM
Va. A. Bandel, and
E.A. Heger
Agronomy Department
Cooperative Extension
Service
September 1994
University of Maryland
Soil Reserve
• Soil test
- university lab
- private labs
• Frequency of testing
- depends on crop and management
• Typical test looks at P, K, Ca, Mg,
O.M., and pH. Minors are as needed.
Fig. 1-1: Phosphate Recommendation (lbs/A)
as a function of soil fertility level (FIV-P)
for corn grain (yield goal-150 bu/A)
110
100
85
70
80
45 45
60
35
40
30
20 20
20
Low
FIV-P
Optimum
Medium
90
70
50
30
0
0
10
# P205/A
65
110
120
Excessive
Crop Residue
• Benefits left by a previous crop or
cover crop
• Previous crops leave little unless it
was a leguminous crop
• Leguminous crops leave nitrogen
• The amount of N left depends on the
species of legume and the stand
density and maturity.
• Cover crops are not harvested and will
recover nutrients otherwise lost.
Manure
Analysis is available from the University
of Maryland’s Soil Testing Laboratory.
How much of the nitrogen in
manure is plant-available?
It depends on:
* the nitrogen content
* animal species
* incorporation practices
Figure 2- 3b. Distribution of organic nitrogen
& ammonium nitrogen in dairy manure
3
Ammonium
nitrogen
Organic
nitrogen
9
This dairy manure contains 12 pounds of total nitrogen per ton.
Available Organic Nitrogen
Only part of the nitrogen in manure
becomes plant-available -- through the
process of mineralization -- the year it’s
applied.
Nitrogen “Credits”
• Organic nitrogen in organic sources
continues to break down or mineralize
for several years after application.
• The largest proportion of this organic
nitrogen breaks down and becomes
available in the year of application.
• Organic sources include manure,
biosolids (sludge), and composts.
Nitrogen “Credits”
• Progressively smaller amounts of the
organic nitrogen break down and
become available in the subsequent
years.
• Credit needs to be given to this
available nitrogen from previously
applied manure to the current year’s
nitrogen recommendation.
Figure 2- 4b: Distribution of Available Nitrogen
from Organic and Ammonium Nitrogen
Components in Dairy Manure
Ammonium
nitrogen
0.6
lb
2.4 lb
6 lb
3 lb
Available
ammonium
nitrogen
Available
organic
nitrogen
Organic
nitrogen
This dairy manure contains 12 pounds of total nitrogen and
5.4 pounds of available nitrogen per ton
A funny slide to breakup the class. This could be an Iraqi surface to air
missile.
Don’t Overload!
Manure Mineralization Factors
•Vary by animal species.
The mineralization rate of manure varies
between animal species. A table
explaining these differences can be found
in the Nutrient Applicator Guide on page
10.
•See Table 2-1 in the
Nutrient Applicator Guide.
Available Ammonium Nitrogen
• NH4 is a plant-available form of N.
• When manure is left on the soil surface after
application, it can be lost through the
process of volatilization.
Nitrogen Loss
Estimated Manure Values
• Dairy (fresh, spread daily)
89% moist. 7 - 3 - 6 (lb/T)
• Dairy (stored outside, leachate lost)
87% moist. 3 - 2.5 - 4 (lb/T)
• Poultry (layer stored in pit)
65% moist. 25 - 27 - 24 (lb/T)
• Swine (storage tank beneath slotted
floor) 95% moist. 2.5 - 3 - 5 (lb/T)
• Beef (bedded manure pack under roof)
80% moist. 5 - 4 - 8 (lb/T)
Example: Calculating Quantity of Dairy
Manure to Meet Crop Nutrient
Recommendation
Ralph Gonzales Farm
• PAN content of semi-solid dairy
manure is 6 lbs./T
• wants to supply the N for his corn crop
• yield goal is 120 bu/A
• incorporates the manure the same day
as application
• see Example 4-2, p.19 in training guide
Calculating Quantity of Dairy Manure to
Meet Recommendation
Note: The nitrogen recommendation
for corn grain is 1 lb./A of PAN per
bushel of yield.
1) RECORD nitrogen recommendation
(lbs./A) from the nutrient management
plan.
120 lbs./A
2) RECORD PAN of manure (lbs./T)
6 lbs./T
Calculating Quantity of Dairy Manure to
Meet Recommendation
CALCULATE the quantity of manure
required in T/A: divide the nitrogen
recommendation by the PAN of manure.
120 lbs./A ÷ 6 = 20 T/A
Twenty tons of a dairy manure with
this PAN are needed to provide 120
lbs./A of PAN.
Done!
Use of Raw Manure
• Heavy applications can throw off
nutrient balance
• Excess available N can lead to
excessive growth and nitrate buildup
in plant
• Plants with high nitrates do not store
as well and attract insects
• Nitrogen and phosphorus are
pollutants
• Weed seeds pass through animals
Often Forgotten Sources of N
• Carryover from past manure/biosolids
• Cover crops ( fixed & recycled N)
• N released from soil organic matter
(40-80 lb/A)
• Nitrates in rain & irrigation water
• Weeds, plowed down have slow-release N,
85 lb/T pigweed, 80 lb/T lambsquarter
• Crop residues, humus, bedding, and
composts
Component
Input to soil
Loss from soil
The Nitrogen Cycle
Atmospheric
nitrogen
Atmospheric
fixation
and deposition
Industrial fixation
(commercial fertilizers)
Crop
harvest
Animal
manures
and biosolids
Volatilization
Plant
residues
Runoff and
erosion
Biological
fixation by
legume plants
Plant
uptake
Denitrification
Organic
nitrogen
Ammonium
(NH+4)
Nitrate
(NO-3)
Leaching
Component
Input to soil
Loss from soil
The Phosphorus Cycle
Crop
harvest
Animal
manures
and biosolids
Atmospheric
deposition
Mineral
fertilizers
Plant
residues
Organic phosphorus
•Microbial
•Plant residue
•Humus
Leaching
(usually minor)
Plant
uptake
Soil solution
phosphorus
•HPO4-2
•H2PO4-1
Primary
minerals
(apatite)
Runoff and
erosion
Mineral
surfaces
(clays, Fe and
Al oxides,
carbonates)
Secondary
compounds
(CaP, FeP, MnP, AlP)
Component
Input to soil
Loss from soil
The Potassium Cycle
Crop
harvest
Plant
residues
Animal
manures
and biosolids
Mineral
fertilizers
Runoff and
erosion
Plant
uptake
Exchangeable
potassium
Soil solution
potassium (K+)
Leaching
Mineral
potassium
Fixed
potassium
Input to soil
Component
Loss from soil
The Sulfur Cycle
Atmospheric
sulfur
Atmospheric
deposition
Volatilization
Crop
harvest
Mineral
fertilizers
Animal
manures
and biosolids
Plant
residues
Runoff and
erosion
Elemental
sulfur
Absorbed or
mineral sulfur
Plant
uptake
Organic
sulfur
Reduced sulfur
Sulfate
Sulfur
(SO-4)
Leaching
Fertilizer Application Terms
• Broadcast
- fertilizer is applied uniformly to
entire field before crop emerges
• Topdress
- fertilizer is applied uniformly to
entire field after crop emerges
• Plowed down or tilled in
- fertilizer is applied to field then is
tilled in with a disk or a plow
Fertilizer Application Terms
• Banded
- fertilizer is applied directly over
the top of the crop row, generally
before the crop emerges, omitting
the area between the rows
• Side-dressed
- fertilizer is applied directly to
growing crop, generally in a band
at the base of the plant
Calibrating Nutrient
Application Equipment
• Calibration is a way to set your
application equipment to apply
material uniformly at the desired rate.
• It insures application of the required
amount of nutrients without overfertilizing.
• Two common methods are used:
- weight-area method
- load-area method
Basics of Calibration
Determining the square feet in an area is basic to
the calibration of farm equipment. The size of an
area can be determined by multiplying length X
width.
L
e
n
g
t
h
L
e
n
g
t
h
Area = Length x Width
Width
Width
How to Calibrate Nutrient
Application Equipment
• Measure the actual rate of application.
• Compare actual application rate to the
recommended application rate.
• If the application rate is substantially
greater or less than the recommended
rate, try:
- changing equipment settings, or
- changing ground speed of the
tractor
Load-Area Method
Know:
• capacity of the spreader
• size of the area where manure is
spread
Apply nutrient supplying material,
then measure area of application.
Project rate of application to a per-acre
basis.
Weight-Area Method for
Manure
1. Arrange at least 3 plastic sheets in the center
of the spreader’s path.
2. Drive the spreader over the center of the
sheets at a known speed with specific
equipment settings.
3. Collect & weigh the manure on each sheet.
4. Average the quantity applied to the sheets
and project to T/A.
Weight-Area Method
• Works well with calibrating fertilizer
spreaders and planters.
• Works well with calibrating both dry and
liquid manure spreaders.
- pans can be used to catch liquid manure
- plastic sheets can be used to catch dry
manure
Basics of Calibration
Using Sheets and Pans
This diagram shows how pans and sheets can be arranged in a field to calibrate a spreader.
1
Spread
2 manure
2
1
3
4
7
5
Spread manure
8
6
3
9
10
Refer to your “Nutrient
Applicator’s Training Guide “
for additional help
Let’s take a quick look at some
other materials we apply to
our soils.
Limestone
• Supplies calcium and magnesium
• Mined calcium carbonate is the
principle liming material, typically
50% oxides
• CaCO3 equivalent is the basis for
liming material recommendation rates
• Comes in various forms and grades
Comparing Liming Materials
Effective Neutralizing Value
E.N.V.
This is a comparative value that refers
to the ability of a liming material to
modify soil pH within a year.
Reference Standard:
Calcium carbonate (CaCO3)
E.N.V.= 100
This means that liming
materials are compared
(greater than or less than) to
the neutralizing ability of
calcium carbonate. E.N.V.
can be found on the labels of
liming materials and fertilizer
as an indicator of the
products impact on soil pH.
Limestone
• Mesh size determines how quickly it
reacts in the soil
• Good quality ag lime is typically 80%
90-100 mesh and 20% 40 mesh
• Ground dolomite (dolomitic lime) is
over 10% magnesium; it is a good
source of Mg when needed
Other Liming Agents
• These are typically industrial
byproducts
• These include stack dust, sludge lime,
and river mud
• Domino Sugar lime is a new source
• Solubility and % oxides vary, so get an
analysis
• These contain mostly Ca and traces of
other elements and materials
Liming Recommendations
• Know the analysis, especially % oxides
-Application rate is based on lb/A
oxides
• % calcium and magnesium
- may not need additional Mg
• Oxide form of calcium (CaO) is readily
available
• Mesh size of carbonate form of Ca
(CaCO3 ) reflects its availability
- smaller particles work faster
Liming Notes
• Limestone recommendations are based on
raising the pH of the plow layer (top 7-9”)
to 6.5; except for special crops; i.e. alfalfa.
• Limited to 1,500 lb/A oxides/year when not
incorporating; i.e. pastures
• Avoid applying liming products and
fertilizer at, or around the same time.
• Liming materials laying on the surface will
neutralize pesticides.
Compost
Decomposed Plant & animal Matter
• When correctly done:
- pH is near neutral
- C:N ratio is 15:1
- Majority of weed seeds & disease
organisms are dead
- Offers a well balanced slow release
supply of nutrients
- As much as 1/4 of compost weight is
microbes (dead & alive)
Principles of Composting
• Best composts come from piles with
the highest microbial activity
• Temperature is easiest sign of
microbial activity
• Good composts heat to approximately
140 - 1600 F within the first 3 or 4 days
Principles of Composting
• Small particle size makes a greater
surface area available to microbes
- particles that are too small
however can pack a pile
• Adequate volume, or size of pile keeps
it from cooling too quickly
- piles 4 x 4 x 4 ft. do well
Unfinished Composts
• Can hurt crops
• Chemicals formed in process are toxic
to plants
• N can be tied up
• Good composts take 12 - 18 months
• Moisture must be adequate (50 - 70%)
similar to a squeezed sponge
• C:N ratio in initial pile should be 30:1
Common C:N Ratios
• Undisturbed top soil
10:1
• Alfalfa
13:1
• Rotted barnyard manure 20:1
• Corn stalks
60:1
• Small grain straw
80:1
• Oak
200:1
• Spruce
1000:1
Compost Problem Solving
• Bad Odor
- not enough air
- turn the pile more frequently
• Center of pile too dry
- not enough water
- moisten while turning
Compost Problem Solving
• Pile is damp & warm in center, but nowhere
else
- pile is too small
- collect more material and mix the old
ingredients into a new pile
• Pile is damp and sweet smelling, but will
not heat up
- lack of nitrogen
- mix in N-rich material like fresh
grass, manure, or urea
Crop Rotation and Cover Crops
• Benefits crop fertility
- fixed and recaptured nutrients
• Benefits soil structure (tilth)
- cover crops add organic matter
- variability in root growth
improves soil pores and water
penetration
• Pest management
- breaks the parasite life cycle
• Harvest vs. cover crop is the decision
Some Parting Advice
• Seek help when you are not sure about what
you are doing. There are a lot of resources
out there for you.
• Don’t be like the old farmer who told the
County Agent that he did not need any
advice. He told the Agent that he has
already worn out two farms and that he had
his own way of doing things.
THANK YOU