Rock phosphate enriched compost: an approach to improve low-grade Indian rock phosphate.
In this study, rock phosphate enriched composts (RP-compost) were prepared by mixing four low-grade Indian rock phosphates with rice straw with and without Aspergillus awamori. RP-compost had higher total P, citrate soluble P (CSP), organic P (Org.P), acid and alkaline phosphatase activities, and lower water soluble P (WSP) and microbial biomass C (MBC) than normal compost. Inoculation with A. awamori increased total P, WSP, CSP, Org.P, MBC and acid phosphatase activity. RP-compost recorded lower Olsen P at the initial period of incubation study than diammonium phosphate (DAP), but improved significantly with the progress of time. RP-compost prepared at 4% charged rate resulted in higher Olsen P throughout the incubation period compared to 2% charged rate. Similar trend were obtained with those RP-composts prepared with A. awamori. Data on pot experiment revealed higher yield and P uptake by mungbean (Vigna radiata) due to addition of RP-composts over control. The effectiveness of RP-compost ranged from 61.4% (MussoorieRP-compost) to 94.1% (PuruliaRP-compost) as that of DAP on dry matter yield and 48.8% (JhabuaRP-compost) to 83.7% (PuruliaRP-compost) on total P uptake. Enriched compost prepared at 4% charged rate recorded 15.8% and 10.6% extra yield and P uptake, respectively by mungbean over 2% charged compost. Also RP-compost inoculated with A. awamori resulted in 13.0 and 21.5% extra yield and P uptake than without A. awamori treated group. Thus, RP enriched compost could be an alternative and viable technology to utilize both low-grade RPs and rice straw efficiently.
Division of Soil Science and Agricultural Chemistry, Indian Agricultural Research Institute, New Delhi, India. drb_ssac@yahoo.com
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Biswas
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Narayanasamy
D001230:Aspergillus / Q000378:metabolism*; D005308:Fertilizers / Q000032:analysis* / Q000382:microbiology; D007194:India; D012275:Oryza / Q000378:metabolism* / Q000382:microbiology; D010710:Phosphates; D012987:Soil / Q000032:analysis*; D012988:Soil Microbiology
D005308:Fertilizers; D010710:Phosphates; D012987:Soil