Build-up of Soil Organic Carbon, Nitrogen and Phosphorus and their Mineralization with the Long-term Application of Phosphatic Fertilizers

摘要

Soil organic C, N and P levels and their mineralization were studied in a pearl millet-wheat cropping sequence receiving phosphatic fertilizers varying in their water solubility for the last 35 years. The maximum increase in soil organic C and total Nwas observed with the application of water soluble P sources such as single super phosphate (SSP), diammonium phosphate (DAP) and urea ammonium phosphate (UAP), compared to partially water soluble P source such as suphala, and insoluble P source such asMussoorie rock phosphate (MRP). There was more accumulation of soil organic C and N when SSP, DAP and UAP were applied @ 60 kg P_2O_5/ha as compared to 30 kg P_2O_5/ha. The rate of C, N and P mineralization increased from 5.4, 0.82, 0.01 to 12.4, 1.29 and 0.089 mg/kg soil/day, respectively, in P fertilized soils.