There are four main approaches to fertilizer recommendations based on soil testing: 1. The build up and maintenance approach applies more fertilizer to increase long-term soil nutrient availability, which decreases the risk of deficiencies but increases the risk of over-fertilizing. 2. The sufficiency approach applies only what is needed for maximum crop profit in a given year while minimizing costs. Higher rates are used when soil tests are low. 3. The basic cation saturation approach aims to maintain specific ratios of calcium, magnesium, and potassium in soil. 4. The quantitative approach uses soil test values directly to calculate fertilizer needs based on crop type, production factors, and nutrient removal by the crop.

1. CONCEPT OF SOIL TEST BASED BALANCE
FERTILIZER APPLICATION AND IPNS APPROACH

2. INTRODUCTION
An approach for giving fertilizer recommendation refer to
the way conclusions are drawn based on soil test.
Soil testing labs and crop
consultant may give
different recommendations
based on the same test
result if the use different
approaches. This may be
very confusing to both
grower and the person who
gives the recommendation.

3. BASIC FERTILIZER RECOMMENDATION
APPROACHES
There are four basic fertilizer recommendation approaches
:-
1. Build up and maintenance approach
2. Sufficiency approach
3. Basic cation saturation approach
4. Quantitative approach

4. THE BUILD UP AND MAINTENANCE
APPROACH
In the build up and maintenance approach, nutrient
availibility in the soil is increased over time for
future years.
In this approach more fertilizer is used. Therefore, the
risk of nutrient deficiencies related to there
availability in soil is decreased.
This approach also holds the risk of over fertilizing
and negative impact on the environment.

5. THE SUFFICIENCY APPROACH
 In this approach, fertilizer are applied only to meet
the nutrient requirements of the crop. The goal of
this approach is to maximum profitability in a given
year, while minimizing fertilizer application and cost.
 When soil test level are low, fertilizer rates that are
higher than the nutrient removal of the crop are
recommended.

6. THE BASIC CATION SATURATION
APPROACH
 This approach assume that a specific ratio of
cations (positive charged) must exist in the soil in
order to achieve maximum yield. It concern only
with rcommendations for calcium, magnesium and
potassium.
 According to this concept, the proportion of cations
should be 65-85% Ca, 6-12% Mg, and 2-5% K

7. THE QUANTITATIVE APPROACH
 This approach uses the soil test values as the
actual amount of nutrient available in soil.
 This approach is very easy to understand and
implements.
 Calculation of fertilizer is done on the basis of
different production factor like – type and variety of
crop, production level, soil type, and type and
method of use of fertilizer etc.
 Total nutrient requirement =
Nutrient supply by soil + nutrient supply by fertilizer
 Quantity of fertilizer nutrient =
Total nutrient requirement- nutrient supplied by soil

8. DIFFERENT METHODS OF FERTILIZER
RECOMMENDATION
In our country , three methods are generally used:-
A) Fertility group approach :- on the basis of soil test, soil
is categorised in to low, medium and high fertility groups
and ferilizer is recommended as per following table :
GRD = General recommended dose
Fertility level of soil Fertilizer recommendation
Low GRD + 50% of GRD
Medium GRD
high GRD – 50% of GRD

9. B) Critical level approach :-
in this method soil are divided
in to two categories on the basis of soil fertility level, this
dividing level is known as critical level.
Beneficial result of fertilizer use may be
received from the soil which have fertility level below
this critical level but the possibility of beneficial result
are very less if fertility level is above the critical level.
- This approach generally used for micronutrients.

10. C) Target Yield approach :-
for obtaining a given yield, a definite
quantity of nutrient must be taken up by the plant.
once this is known, the fertilizers that need to
be applied can be estimated by taking into account the
efficiency of contribution from soil available nutrients and
the efficiency of uptake from applied fertilizer nutrient
towards total uptake of the nutrient.
This form the basis of fertilizer recommendation for
targeted yield of a crop.

11. References
A) www.agriinfo.in Methods of fertilizer application
B) Soil management :- Dr. G.K. Sharma
Dr. D.S. Thakur
Sh. J.L. Chaudhary

12. THANK YOU