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R. K. Kaleeswari ¹

Affiliations
1 Department of Soil Science and Agricultural Chemistry, Tamil Nadu Agricultural University, Coimbatore (T.N.), IN

Abstract

The efficiency of P fertilizers of varying water solubility was evaluated by comparing the grain yield, P uptake and economic returns. The results revealed that application of SSP @ 50 kg P₂O₅ha^-1+ Azophos @ 2 kg ha^-1+ FYM @ 12.5 tha^-1 recorded the highest grain yield (4760 kg ha^-1). Among the P sources, highest grain yield was recorded due to the application of SSP as compared to URP. Among the microorganisms inoculated, Azophos enhanced the rice yield followed by VAM and phosphobacteria. The B: C ratio was higher under SSP @ 50 kg P₂O₅ ha^-1 + Azophos @ 2 kg ha^-1. Though the B:C ratio was low in FYM treated plots, incorporation of FYM increased the grain yield and P uptake. For better dissolution of P, Azophos can be used as an efficient P solubilizer under low land ecosystem.

Keywords

Rice Yield, Phosphorus, P Solubilising Microorganisms, Phosphorus, Uptake, FYM.

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R. K. Kaleeswari ¹

Affiliations
1 Department of Soil Science and Agricultural Chemistry, Tamil Nadu Agricultural University, Coimbatore (T.N.), IN

Abstract

Field experiments were conducted with rice under flooded condition to evaluate the efficacy of various soil tests for available P. Available P status as estimated by different extractants and its relationship with different inorganic P forms as influenced by various organic manures and P fertilizers under wetland ecosystem is reported.Among different indices of P availability,Olsen’s soil test was found to be the most suitable method.The P extracting power of different extractants was in the order: Mehlich I > Bray I > Truog > Olsen > Morgan. Olsen and Bray No.1 extractants were consistent in extracting P from specific P fractions than the other three extractants. Iron-P was the dominant inorganic P fraction followed by Ca-P, Al-P and saloid-P. Available P in this rice soil depended on the concentration of Fe-P and saloid-P. Inorganic P forms jointly contributed to 94 per cent variations in Olsen-P.

Keywords

Labile P, Soil Tests, Inorganic P Forms, P Fertilizers, Organic Manures.

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