Transcript Fertilizers and Fertilizer Management

Fertilizers & Fertilizer
Management
A Game Changer
 Factors Affecting Fertilizer Use
 Types of Fertilizers
 Fertilizer Analysis
 Fertilizer Application methods
 Fertilizer Timing and Ingredients
What are Fertilizers
Fertilizers are sources of plant nutrients that
can be added to soil to supplement its
natural fertility
They are intended to supply plant needs
directly rather than indirectly through
modification of such properties as soil pH
and structure
Fertilizer needs are based on ecosystem
needs (forests, agronomic, urban).
Rise in Fertilizer Use
In general, use of fertilizers in agriculture has seen
dramatic rise across the industrialized economies that make
use of about 80% of all manufactured fertilizers.
Of the 80% of the fertilizer used by those economies, the
United States alone uses about 30% of it.
Fertilizer Changed the World
Modern Agriculture
Subsistence Agriculture
Change from agrarian society and subsistence
agriculture to modern/mechanized agric is marked by
increase in use of fertilizers
Factors Affecting Fertilizer Use
1. Crop factor
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Crops differ in requirements of nutrients
Varieties of the same crop differ as well
2. Soil factor
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Ability of soil to supply nutrients is different
for different soils
Degradation problems may also be different
Factors Affecting Fertilizer Use
3. Climatic factor
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Areas of low rainfall limit fertilizer efficiency
Case in hand, East and West of the US
4. Economic factor
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Price determines how much fertilizer to afford
Crop prizes have the opposite effect
5. Management factor
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Personal preferences for doing things in
particular ways
Biases for and against fertilizer use.
Types of Fertilizers
There are different ways of classifying
fertilizers.
a. Mineral or Organic classes
b. Method of preparation
c. Fertilizer Analysis
Types of manufactured Fertilizers
The most common classification of
fertilizers is that based on the method of
preparation
1.
2.
3.
4.
Single-compound fertilizers
Mixed manufactured fertilizers
Bulk-blend fertilizers
Liquid-mixed fertilizers
Single-compound fertilizers
Single compound fertilizers consist of only one of
the primary nutrients (NPK)
Has advantage of having a known analysis
ie., every grain of fertilizer has the same composition.
• E.g., ammonium nitrate (34-0-0), urea (46-0-0), liquid nitrogen
(30-0-0), superphosphate (0-46-0), potash (0-0-60)
A few single compound fertilizers combine two
fertilizer elements in one compound.
• E.g., ammonium phosphate, potassium nitrate.
Mixed manufactured fertilizers
These are essentially mixed fertilizers
Traditional means of marketing mixed fertilizers
Manufactured fertilizers are marketed in pelletized
form.
Ingredients of manufactured fertilizers are thoroughly
mixed in a moist condition and passed through a rotating
drum to granulate it as it dries.
And the ingredients are chosen to contain a desired
concentration of nutrients but also to granulate well.
Granules do not stick together even after storage.
Bulk-blend fertilizers
Bulk blend is a flexible way of producing
fertilizer of any specified ratio.
These fertilizers are manufactured by
mixing single-compound fertilizers.
Less homogenous than manufactured fertilizers
Segregation of granules may occur before use
Mainly small factories to serve local areas
engage in this.
Liquid fertilizers
Fertilizers that have all nutrient elements in
forms that are soluble in water and therefore
can be applied in liquid form
Liquid can be spread to give a uniform
distribution
Liquid can be added to irrigation water
But corrosive-resistant equipment is required
Fertilizer Analysis
(What the Law says)
Code of Alabama - Title 2: Agriculture - Section 2-22-7 - Labeling of
commercial fertilizers (Acts 1969, No. 434, p. 840, §6.)
Any commercial fertilizer sold in this state for use therein or sold for
importation into this state for use therein in containers shall have printed
on or affixed to the container a label setting forth in clearly legible and
conspicuous form the following information:
(1) The net weight
(2) The brand and grade
(3) The guaranteed analysis
(4) The materials from which the plant nutrients are derived with the
percentage of each as may be required by regulations of the board; and
(5) The name and principal address of the manufacturer or
other person responsible for placing it on the market.
Fertilizer Analysis
(What is in a fertilizer?)
Laws require periodic registration of brands and
accurate labeling of fertilizer grades as follows:
Fertilizer Analysis (contd)
What does 10% N mean for your fertilizer?
10 % total N (Kjeldahl digested)
Calculating N content
N/B atomic mass of N=14
Mass of 1N/N = (1*14)/(1*14) = 1.0
10 % N*1 = 10% N
Therefore the fertilizer contains 10 % Nitrogen.
Fertilizer Analysis (contd)
What does 20% P2O5 mean for your
fertilizer?
20 % P2O5 (Phosphate soluble in dilute ammonium
citrate)
Calculating P content
N/B atomic mass of P=31
Mass of 2P/P2O5 = (2*31)/((2*31) + (5*16)) =
62/142 = 0.44
20 % P2O5*0.44 = 8.8 % P
Therefore the fertilizer contains 8.8 % Phosphorus.
Fertilizer Analysis (contd)
What does 10% K2O mean for your
fertilizer?
10 % K2O (Water soluble)
Calculating K content
N/B atomic mass of K=39
Mass of 2K/ K2O = (2*39)/((2*39) +16) = 78/94 =
0.83
10 % K2O*0.83 = 8.3% K
Therefore the fertilizer contains 8.3 % Potassium.
Fertilizer Analysis (contd)
Fertilizer Analysis
10
20
10
10%N
20%
P2O5
10%
K2O
10% N
5 lbs
8.8% P 8.3% K
4.4 lbs 4.2 lbs
Examples of Nitrogen Fertilizers
Inorganic N Fertilizers
Urea
(NH2)2CO
Ammonium nitrate NH4NO3
Ammonium sulfate (NH4)2SO4
46%
33%
21%
Organic N Fertilizers
Bone meal
Chicken manure
Biosolids
4%
2%
2-12%
Nitrogen Fertilizers Efficiency
N Fertilizer efficiency refers to the portion of
the added fertilizer used by the crop
Nitrogen, fertilizer efficiency ~30-70%
N losses are due to:
Denitrification
Leaching
Immobilization
N efficiency is increased by:
slow release fertilizers
Periodic additions
Irrigation methods
Phosphorus Fertilizers
Rock Phosphate + H2SO4
Superphosphate
16-20% P2O5
Rock Phosphate + H3PO4
Triple
superphosphate
46% P2O5
Examples of Phosphorus Fertilizers
Ca(H2PO4)2
Monoammonium phosphate
NH4H2PO4
Diammonium phosphate (NH4)2HPO4
Basic slag
Rock Phosphate
Apatite
Bone meal
Superphosphate
P fertilizer efficiency is 10-30%.
P losses are due to
• P-fixation
• Soil erosion
• Leaching
16-46%
48%
53%
15-25%
25-30%
23-30%
Potassium Fertilizers
Muriate of Potash KCl
Potassium sulphate K2SO4
Potassium nitrate KNO3
60%
48%
44%
K-fertilizer efficiency is 50-80%
K-losses are due to:
Erosion
Leaching
K-fixation by soil clay
Fertilizer Ingredients
Carriers of N-P-K
Most fertilizers are salts
E.g., of salts (carriers) are (NH4)2SO4,
Ca(H2PO4)2, KCl, etc.
Soil conditioners
Acidity neutralizers
Micronutrients
Herbicides
Fertilizer Application Methods
1.
2.
3.
4.
5.
6.
Soil Injection
Broadcasting
Banding
Side or Top Dressing
Folia Spray
Fertigation (irrigation water)
Fertilizer Application (contd)
Soil injection of fertilizer. E.g., anhydrous ammonia
application
Fertilizer Application (contd)
Fertilizer broadcasting –application involves
broad coverage of an area.
Fertilizer Application (contd)
Fertilizer banding –application involves placement
of fertilizer in a narrow band below and to the side
of the seed
Fertilizer Application (contd)
Top or side dressing fertilizer application –application
is on top and by the side of a crop after the crop has
emerged.
Fertilizer Application (contd)
Folia spray fertilizer application – application
involves spraying fertilizer directly unto the
foliage. This is common with micronutrients.
Timing of Fertilizer Application
The timing of fertilizer application is governed by
many factors:
Making the nutrients available when the plants
need it.
Avoiding excess availability before and after
uptake.
Making nutrients always available for long season
plants and perennial plants.
Conducting application when field conditions make
it possible.
Timing temperate climates
Fall application
Fall is often the most convenient time because:
• Soil will support a spreader truck better
• Fertilizer may be cheaper
• Time and labor may be more available
Spring application
Better fertilizer efficiency due to reduced leaching.
Periodic application
Periodic application during the growing season
increases the fertilizer efficiency.