Definition and introduction of fertilizer use efficiency , Causes for Low and Declining Crop Response to Fertilizers and FUE.Methods to increase fertilizer use efficiency.

1. Fertilizer Use Efficiency
Manasa Muppa
M.Sc Agronomy
Lovely Professional University

2. DEFINITION
• Fertilizer use efficiency is that the output of any crop per unit of
the nutrient applied under a specified set of soil and
atmospheric condition.
• When a fertilizer is applied all of its nutrients aren't absorbed
by the crop. Only fraction of the nutrients is used by the crop.

3. INTRODUCTION:
• Based on the nutrient supplying power of soils as determined by soil test values, fertilizer
recommendations are made. The aim is to get Maximum economic yield with minimum
inputs. Of the various inputs fertilizer is the costly input. This costly input must be
efficiently used and utilized.
• The Efficiency of fertilizer N is only 30-40% in rice and 50-60% in other cereals, while
the efficiency of fertilizer P is 15-20% in most crops. The efficiency of K is 60-80%,
While that for S is 8-12%. As regards the micronutrients, the efficiency of most of them is
below 5%.

4. Causes for Low and Declining Crop Response to Fertilizers and FUE
• Nutrient Supply and Soil fertility related
• NAAS (2006) listed the following causes of declining crop responses to fertilizers:
• Continuous use of fertilizer N alone or with inadequate P and K application leading to mining of
native soil P and K
• Continued practice of intensive cropping systems like 'rice-wheat' with high yielding varieties
even under recommended NPK use, impoverishing soils of secondary and micro nutrients
especially S, Zn, Mn, B and Fe
• Use of high analysis fertilizers and inadequate addition of organic manures resulting in
widespread deficiencies of S and micronutrients

5. • Fertilizer application mostly not based on soil-test values
• Inappropriate time and method of fertilizer application
• Excessive use of irrigation in rice-wheat cropping system, sugarcane and other heavily fertilized
crops leading to leaching of nitrogen and other plant nutrients
• Inadequate availability of appropriate kind of fertilizers at the right time • Antagonistic
reaction between some plant nutrients
• Low status of soil organic carbon

6. • Subsoil impedance to plant root system restricting nutrient uptake
• Soil degradation due to high salinity/sodicity/acidity/waterlogging, affecting nutrient availability
• Lack of adequate and quality soil testing facilities and meagre availability of fertilizer
recommendations under aberrant weather conditions
Environmental degradation, having negative impact on below ground biodiversity, especially
agriculturally important microorganisms.

7. Seed related
• Non-availability of sufficient quantity of seeds of high yielding varieties of crops at affordable
price and at the appropriate time
• Lack of more efficient nutrient using genotypes.

8. Agronomic Practices
• Delayed sowings / plantings
• Low seed rates resulting in poor crop stands
• Poor weed management
• Inefficient tillage
• Inefficient irrigation and rainwater management
• Large scale monoculture
• Lack of consideration of previous cropping in the same field
• Lack of capturing water-nutrient synergic interaction
• Inadequate plant protection.

9. Weather Aberrations
• High intensity rain leading to nutrient loss
• Abnormal high/low temperature.

10. Methods to increase fertilizer use efficiency
• Fertilizers are considered as efficient when maximum yield is obtained with minimum possible amount
of fertilizer application.
• It is indeed difficult to quantify the efficiency of a particular fertilizer since it depends on:
1. Losses due to leaching.
2. Losses in Gaseous forms
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 7. fertilizer characteristics.

11. Type of fertilizer also decide the efficiency:
• Under varied Indian conditions, ammonium and urea fertilizers are more efficient for paddy than
nitrate fertilizers.
• Water soluble phosphorus compounds are more effective for short-term crops and in soils that
range from neutral to alkaline.
• Crops and fertilizers have also been seen to interact in several ways. Paddy, for example,
performs better when ammonium sulphate is used as a nitrogen carrier, while tobacco performs
better when potassium sulphate is used as a potassium carrier.

12. To get a maximum benefit from fertilizer we should follow the
following practical points:4R concept.
1. Right type of fertilizers with Favorable chemical and physical
properties.
2. Right time of fertilizers application
3. Right dose of fertilizers based on nutrients supplying power of soils and
crop need.
4. Right method of application.

13. • For plant growth, soil is the most significant source of nutrients. For all crops and cropping systems in
different agro-ecological zones of the country, balanced fertilization or site-specific fertilizer application
procedures (SSFAP) based on soil-test recommendations must be developed and implemented.
• Apart from their grade, fertilizers differ in terms of solubility. Fertilizer selection is site-specific and
must be determined through field testing. Potassic fertilizers are less popular than nitrogen and phosphatic
fertilizers. Studies on crop response are also more common for N fertilizers than for P or K fertilizers,
because nitrogenous fertilizers have a higher rate of leaching, and their residual effect is minimal or
negligible. The indirect, residual, and cumulative effects of P are more significant. Nitrogen in the form of
NO3 is more susceptible to leaching. Leaching loss is considerably greater during the rainy season
(kharif) than during the summer, and in sandy soils than in clayey soils. Losses can be reduced by
selecting the right time and manner for application.

14. • To gain the most advantage from the fertilizer nutrient, apply it at the right time. If a nutrient is
given before the period when it is needed, it is lost in various ways or absorbed more than is needed.
When applied late, it is either not absorbed or is not used for the intended function, accumulating in
plant components.
• It is critical to put fertilizer in such a way that the nutrient is freely accessible to the crop in order
to maximize fertilizer efficiency. It needs to be close to the roots. Surface broadcast, furrow bottom,
deep at or slightly below the root zone, top dressed, side dressed, or to foliage are all options. The
type of crop, rooting pattern, feeding area, and ease of application all have a role. The interplay of
soil, crop, and fertilizer influences the technique of application as well.