Methods of Fertilizer Recommendations to Crops By Dr.P.C.Patel

APPROACHES FOR GIVING FERTILIZER RECOMMENDATION
An approach for giving fertilizer recommendations refers to the way conclusions are drawn based on soil tests. The best approach for making fertilizer recommendations depends on several factors such as type of soil, economics and cropping systems. The combination between the build-up and maintenance concept is widely used.
There are four basic fertilizer recommendation approaches:
Buildup and Maintenance;
Sufficiency;
THE BUILD UP AND MAINTENANCE APPROACH
The Build-Up and Maintenance philosophy takes the approach of first building up the soil fertility level to the high category with additions of specific nutrients whose indexes were interpreted as medium or lower per the soil test.
The strategy here is to maintain soil fertility for future years. The goal is to apply more nutrients than the crop removes, so that the nutrient level in the soil is not limiting the yield.
The fertilizer recommendation are made to apply enough fertilizers to both meet the nutrient requirements of the crop and to build up the nutrient level in the soil to a critical soil test level over a planned time frame. Soil test level is maintained at, or above, the critical level by applying fertilizer rates that replace the nutrients removed by the crop.
THE SUFFICIENCY APPROACH
In the sufficiency approach, fertilizers are applied only to meet the nutrient requirements of the crop. The goal of this approach is to maximize profitability in a given year, while minimizing fertilizer applications and costs.
When soil test levels are low, fertilizer rates that are higher than the nutrient removal of the crop are recommended. When soil test levels are high, reaching the critical soil test level, the recommendation decreases to almost zero.