Integrated Use of Organic and Inorganic N Fertilizers to Improve Crop N Use Efficiency and to Reduce the N Leaching Losses.

Nutrient management plays the paramount role in improving the crop productivity and maintaining the soil fertility. Integrated nutrient management using inorganic and organic fertilizers is important to improve the crop N use efficiency and reducing the N leaching losses. Meat and bone (MBM) could be a potential organic fertilizer that can be used to supplement the inorganic fertilizers such as CaNO₃ for crop N nutrition. We tested two different forms of MBM; hexane-extracted (EMBM) and non-extracted (NEMBM) and different plant products that influences N mineralization (neem & karanja) as N source in supplementing the inorganic N fertilizers, reducing N leaching losses and improving the soil biological properties. The combination of various fertilizers; CaNO₃ (3 and 2 split), NEMBM+CaNO₃ (3 and 2 split), neem oil coated NEMBM+ CaNO₃ (3 and 2 split), karanja oil coated NEMBM+ CaNO₃ (3 and 2 split), EMBM + CaNO₃ (3 split) and a control were used. The effect of different treatments on soil N levels, NO₃^- leaching, soil protease activity and corn grain yield were measured.

Combination of organic and inorganic fertilizers resulted in a higher soil NH₄⁺ and lowest soil NO₃^- content at 26 days after sowing. We observed significantly higher NO₃^- leaching losses from the soils with CaNO₃ application at 40 DAS. Extracted MBM recorded significantly higher leaching losses at 40 DAS as compared to NEMBM treatments. Highest corn grain yield was recorded in the neem coated NEMBM with 3 split application, which was statistically similar to the all other NEMBM, 3 and 2 splits and CaNO₃ three split application rates. However, CaNO₃ two splits application and EMBM, 3 split application recorded significantly lower grain yield as compared to all other fertilizer treatments except control. Non-extracted MBM could be successfully used as supplement fertilizer to the inorganic fertilizers with benefit of reduced NO₃^- leaching.