EVALUATION OF PHOSPHORUS ENRICHED POST-METHANATION BIOSLUDGES AS PHOSPHORUS SOURCES: CHEMICAL SPECIATION AND FIELD STUDY

Abstract

□ Phosphorus enriched post-methanation biosludges (PEMB) from molasses-based distilleries have been developed and evaluated as phosphorus (P) sources for rice-wheat rotation under field condition in a Mollisol. Chemical speciation of P and calcium (Ca) in the aqueous solution of these new P sources PEMB 1 (5.1% P) and PEMB 2 (7.61% P) revealed that a higher proportion of soluble Ca in single superphosphate (SSP) existed as free Ca²⁺ while it was complexed by dissolved organic carbon in both PEMB 1 and PEMB 2. In the field experiment, application of PEMB 2 at 16.5 kg P ha⁻¹ resulted in either statistically similar or higher grain yields and total P uptake in both rice and wheat crops than with SSP applied at 22.0 kg P ha⁻¹. Mean apparent P recovery values with PEMB 2 were higher than the respective values observed with PEMB 1 or with SSP applied at 22.0 kg P ha⁻¹.

Keywords:

• apparent P recovery
• post-methanation biosludges
• rice-wheat rotation

ACKNOWLEDGMENTS

This work was financed by the Board of Research in Nuclear Sciences, Department of Atomic Energy, Government of India (2004/35/8/BRNS/257).