Availability and uptake of phosphorus from organic manures in groundnut (Arachis hypogea L.)–corn (Zea mays L.) sequence using radio tracer technique

This investigation was conducted with four organic fertilizer (FYM, poultry manure, vermicompost and sewage sludge) treatments and single superphosphate, all applied on equal P basis at 17 mg (kg soil)− 1. Carrier-free 32P was applied to all the pots and seeded to groundnut. Another set of 24 pots, identical with the first in all respects but without 32P labeling for groundnut crop, was maintained to study the residual effect of treatments on corn. This was labeled with 32P just prior to seeding with corn. In both the crops, the organic fertilizer had a significant effect on the uptake of P as compared to the single superphosphate and control. The highest P content and uptake in groundnut was due to sewage sludge application, Poultry manure accounted for highest uptake of P from soil (%Pdfs). The mean A values ranged from 5.35 to 13.66 mg 100 g− 1 soil, with poultry manure exhibiting the most pronounced effect. In residual corn, the %Pdff was more for the organic fertilizers than for single super phosphate, obviously due to greater residual availability and P release from organic sources. The highest A value was associated with single superphosphate and the lowest with FYM. The highest P uptake, and therefore the highest P use efficiency, was due to FYM.