Research experiences in the past are clearly indicating that soils having low P status respond largely to P fertilization compared to high P status soils. This trend is common irrespective of soil groups although the degree of response may vary (Table 1).

Table 1: Yield response of rice to phosphorus application grown in important soil groups of southern region



Primary Source: Goswami et. al., 1971; Secondary Source: Singh & Sharma, 1994

As per the revised information on soil P fertility status, 70 percent of total 63 districts in four southern states are low in available phosphorus and 30 percent in medium status. None of the districts have high P fertility status, indicating the extent of the phosphorus requirement of these soils (Table 2 ).

Table2: Distribution of southern districts according to the soil phosphorus fertility classes


Source: Hasan, 1996 (Ref: Hasan, R. 1996 Better Crops International 10(2), 4-5)

The information above indicates that crops grown on these soils have a large P requirement and response to P fertilization could be considerable.

Response to P application - IPNI India Programme Experience

India Programme supports various research projects in the region with the view to generate information on the response of various crops to P and K fertilization. The Table below illustrates how crops respond to P fertilization. Besides the essential nature of P in staple food crop production, P fertilization is especially remunerative with cash crops and high value crops.