Effect of Udaipur Rock Phosphate, Single Super Phosphate and Their Combinations on Soil pH, Available Phosphorus, Available P Build up and ΔP in a Groundnut-maize Cropping System on the Acid Alfisols of Odisha State, India.

Abstract

ABSTRACT To find out the effect of low-grade Udaipur rock phosphate (URP), single super phosphate, and their combinations on available soil phosphorus at different growth stages of groundnut-maize cropping system, a field experiment was conducted in a randomized block design with three replications and eight treatments from 2013–2014 to 2015. The soil has a loam texture, a pH of 5.18, low available nitrogen, and medium phosphorus, and potassium. Except for control P, available phosphorus (P) in all treatments increased from an initial value of 14.64 kg ha−1, attained the peak at 30 DAS, and thereafter declined gradually up to the harvest stage. The available phosphorus in treatments at 30 DAS was in order of SSP+ lime > SSP > URP+SSP (1:3) > URP+SSP (1:1) > URP+SSP (3:1) > URP. The highest available phosphorus build-up of 61.7% was obtained when the crop received lime with SSP. The combined application of URP +SSP mixture in 1:1 ratio recorded higher phosphorus accumulation (46.7%) as compared to standard SSP treatment (39.5%). Based onP the method, maximum dissolution in sole URP treatment (T2 and T7) occurred during 30 to 60 DAS of groundnut and maize crop. On the other hand, when the crop received URP+SSP (T4,T,5 and T6) in a different ratios, maximum phosphorus release was recorded at 30 DAS.