Impact of rock-phosphate enriched pressmud and biogass swrry on yield, phosphorus nutrition and utilization by soybean (Glycine max) in a typic hapwstept

Rock phosphate enriched biogas slurry and pressmud alone and in combination with DAP in different ratios (1:3, 1:1 and 3:1) on phosphate basis were evaluated in field with soybean cv. DS-9814 at the institute farm on a sandy loam soil during kharif season of the year 2007 in relation to yield, P uptake, P use efficiency by crop and relative agronomic effectiveness. Increasing levels of P, irrespective of P sources (DAP or manures) significantly enhanced the grain and stover yield and total P uptake by soybean. Among the various ratios of DAP and manures (RPEBGS, RPEPMC and FYM) combination (1:3, 1:1 and 3:1) applied at 80 kg P₂O₅ ha⁻¹, 3:1 ratio performed the highest follows by 1:1 ratio in respect of yield and P utilization. The per cent P utilization in 3:1 ratio (DAP+ RPEBGS) recorded the highest value 19.09. Among the various P sources tried, the performance of DAP was the best followed by RPEBGS and RPEPMC in terms of dry matter yield, P uptake and utilization by soybean. Among manures RPEBGS gave higher relative agronomic effectiveness in terms of grain yield (84.13%) and total P uptake (86%) at 80 kg Pps ha⁻¹ which was further improved with the combined application of DAP and organic source of Pin 3:1 ratio (95.04 and 97.7%).