1. The document discusses nutrient use efficiency and factors that affect it, such as leaching, gaseous losses, immobilization, and chemical reactions between fertilizer components. 2. It describes methods of increasing fertilizer use efficiency, including applying fertilizers at the right time and quantity, and using the proper fertilizer source and form for different crops to minimize fixation and maximize availability. 3. Integrated nutrient management is defined as maintaining soil fertility and nutrient supply through optimizing organic, inorganic, and biological components to provide balanced nutrition for crops while sustaining soil quality.

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Soil Chemistry, Fertility and Nutrient Management
(AGL406)
Mr. Rohitashv Nagar
Assistant Professor & HOD
Department of Agronomy
School of Agricultural Sciences
Career Point University, Kota (Raj.)

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Lecture-6
Nutrient Use Efficiency (NUE)

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Nutrient Use Efficiency : Nutrient Use Efficiency is defined as the amount of
dry matter produced per unit of nutrient applied or absorbed.
Nutrient Use Efficiency : Physiological efficiency X Apparent recovery efficiency
Classification of NUE:
1. Agronomic efficiency: it is defined as the economic production obtained per
unit of nutrient applied. It is calculated by the following equation:
(Grain yield of fertilized crop in kg) - (Grain yield of unfertilized crop in kg)
Agronomic efficiency =
(Quantity of fertilizer applied in kg)

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2. Physiological efficiency: it is defined as the biological production obtained per
unit of nutrient applied. It is calculated by the following equation:
(Total drymatter yield of fertilized crop in kg) - (Total drymatter yield of unfertilized crop in kg)
Physiological efficiency =
(Nutrient uptake by fertilizer crop in kg) - (Nutrient uptake by unfertilized crop in kg)

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3. Apparent recovery efficiency: it is defined as the quantity of nutrient
absorbed per unit of nutrient applied. It is calculated by the following
equation:
(Nutrient uptake by fertilized crop ) - (Nutrient uptake by unfertilized crop )
Apparent recovery efficiency =
(Quantity of fertilizer applied )

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Time of fertilizer application
1. Prior to sowing: Some of water insoluble fertilizers such as rock phosphate
and basic slag are applied 2 to 4 weeks before sowing to enable conversion of
water insoluble form to soluble form for efficient crop utilization . In acid
soils, when lime requirement is 2 ton or less, the entire amount should be
applied at one month before sowing of the crop.
2. At sowing: Application of fertilizer at the time of sowing or just before
sowing is called basal application. A part of recommended nitrogen and entire
quantity of phosphatic and potassium fertilizers are applied as basal.

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3. After sowing the crop: Application of fertilizers after the crop
establishment is called top dressing. Depending on the stage of crop,
generally a portion of nitrogen is applied as top dressing.
4. Split application : When fertilizer is applied at two or more deferent
time, the system is called a split application. For long duration crops, N
must be applied in two or three split doses.

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Method of fertilizer application
A. Soil Application
• Broadcasting: Application of fertilizer uniformly on the soil surface is
known as broadcasting of fertilizer. This is done either before sowing of
the crop or in the standing crop (top dressing). Broadcasting is the most
widely practiced method in India due to ease in application.

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• Band Placement: Application of fertilizers in narrow bands beneath and by the
side of the crop rows is known as band placement of fertilizers. Band placement
is done under the following situations: (I) when the crop needs initial good start,
(2) when soil fertility is low, (3) when fertilizer materials react with soil
constituents leading to fixation, and (4) where volatilization losses are high.
Depending on the root system, fertilizer band is placed directly beneath the seed
or by the side of the row. For crops like castor, redgram, cotton etc., with tap
root system, fertilizer band can be 5 cm below the seed. In cereals and millets,
which produce fibrous root system, it is advantageous to place fertilizers 5 cm
away from the seed row and 5 cm deeper than the seed placement.

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3. Point Placement : Placement of fertilizers near the plant either in a
hole or in a depression followed by closing or covering with soil is
known as point placement of fertilizers.
4. Fertigation : Application of fertilizers with irrigation water is
known as fertigation. This saves the application cost and allows the
utilization of relatively inexpensive water soluble fertilizers. Usually
nitrogenous fertilizers are most commonly applied through irrigation
water. It is generally followed with drip irrigation.

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• Application to plant
1. Root Dipping: The roots of the seedlings are dipped in nutrient solution
before transplanting. In soils deficient in phosphorus, roots of rice
seedlings are dipped in phosphorus slurry before planting.
2. Foliar application: Application of fertilizers to foliage of the crop as
spray solution is known as foliar spray of fertilizers. It is also called non-
root feeding. These solutions may be prepared in a low concentration to
apply any one of plant nutrient or a combination of nutrients. This method
is suitable for application of small quantities of fertilizers, especially
micronutrients.

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INTEGRATED NUTRIENT MANAGEMENT
• Integrated Nutrient Management refers to the maintenance of soil fertility and of
plant nutrient supply at an optimum level for sustaining the desired productivity
through optimization of the benefits from all possible sources of organic, inorganic
and biological components in an integrated manner.
Concepts
• Regulated nutrient supply for optimum crop growth and higher productivity.
• Improvement and maintenance of soil fertility.
• Zero adverse impact on agro – ecosystem quality by balanced fertilization of
organic manures, inorganic fertilizers and bio- inoculants.

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Advantages
• Enhances the availability of applied as well as native soil nutrients.
• Synchronizes the nutrient demand of the crop with nutrient supply
from native and applied sources.
• Provides balanced nutrition to crops and minimizes the antagonistic
effects resulting from hidden deficiencies and nutrient imbalance.
• Improves and sustains the physical, chemical and biological
functioning of soil.

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Fertilizer grade : Fertilizer grade is an expression referring to the legal guarantee
of the available plant nutrients expressed as a percentage by weight in a fertilizer,
e.g. a 12-32-16 grade of NPK complex fertilizer indicates the presence of 12 %
nitrogen (N), 32 % phosphorous (P2O5) and 16 % potash (K2O).
• Fertilizer Mixtures :
• Urea can be mixed with all fertilizers.
• Other fertilizers can be mixed just before use. But the efficiency of the following
fertilizers will be lowered if mixed with the fertilizer or amendment noted against
them.
Ammonium sulphate - Basic slag

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FUE(Fertilizer Use Efficiency):
It may be defined as yield per unit fertilizer input or it may be fresh weight or product yield
per unit content of nutrient.
Nutrient use efficiency of different nutrients
Nutrient Efficiency Cause of low efficiency
Nitrogen 30-50 % Immobilization, volatilization, de-nitrification, Leaching
Phosphorus 15-20% Fixation in soils Al – P, Fe – P, Ca – P
Potassium 70-80% Fixation in clay - lattices
Sulphur 8-10% Immobilization, Leaching with water
Micro-nutrients (Zn, Fe, Cu, Mn, B) 1-2% Fixation in soils

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Factors affecting FUE/NUE
1. Leaching (NO3).
2. Gaseous Losses (NH3,N2O,N2).
3.Immobilization by chemical precipitation, adsorption on exchange
complex and microbial cells.
4.Chemical reactions between various components in fertilizers during
mixing, before application to soil.
5. Physical properties of soil.
6. Chemical properties of soil.
7. Fertilizer characteristics.

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Methods of Increasing Fertilizer Use Efficiency
• Following methods which can be adopted to increase FUE:
• Agronomic methods
• Chemical methods
1. Agronomic methods :
i. Application of fertilizers at right time with required quantity
The phosphates in general are more efficient when the entire dose applied as
basal dressing, potash entire quantity as basal dressing or part as basal and
rest in split doses depending on the soil texture and the nitrogen in 2-3 (or
4) split doses.

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Example:
• In Sugarcane,
Potassium application normally done along with N application because of
better utilization of N, in the presence of K. therefore K is applied at 45,
90 DAS.

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2.Chemical methods :
Synthetic or chemical fertilizers should be good quality and right source for crops.
Examples:
• Oilseed- Generally Sulphate fertilizers like elemental sulphur @ 25Kg/ha, ZnSO4 @ 25
Kg/ha, Borax @ 1-2% application must be done.
• In tobacco plant avoid using of fertilizers containing chlorine for preventing from scorching
effect.
• In tea plantation use of (NH)2SO4 is best.
• In Paddy, Ammonium and urea fertilizer are more efficient for paddy under different Indian
conditions than nitrate fertilizers.

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