Incorporation of rice residue and green gram cultivation saves nitrogen, improve soil health and sustainability of rice-wheat system

Abstract

Rice - wheat cropping system and associated residue burning is a major cause of air pollution and soil health depletion in Northern India. This calls for urgent technological interventions to address the issue and improve the profitability of this cropping system. Objective was to study the effect of rice residue incorporation (RRI) and green gram inclusion (GGI) on amount of N applied, productivity and soil health in rice - wheat cropping (RWC) system. Combinations of RRI, nitrogen management and GGI with conventional rice - wheat rotation were tested for 7 years. Eleven treatments with combination of RRI, RR removal, GGI and N management were evaluated. Treatment effects on system productivity, profitability and soil health parameters were measured. Treatment R - W ( - RR) - Gg + <25 % N to R and R - W ( + RR) - Gg + <25 % N to R + >25 % N to W produced maximum rice (7677kg ha1) and wheat yield (5949kg ha1), though non - significant (P>0.05) compared to control (Rice=7508 & Wheat=5724kg ha1). Nitrogen fertilizer up to 75kg ha1 was saved when GGI was taken up before rice. GGI and RRI was sustainable in terms of higher sustainability value index (SVI=0.78), wheat equivalent yield (WEY=20.0t ha1) and production efficiency (PE=57.5kg ha1 day1). The treatments with GGI + RRI produced 1015$ additional net returns with more than double B:C ratio. Soil health in the form of SOC (0.42 %) and available N (152.6kg ha1) were also improved with GGI + RRI in treatment R - W ( + RR) - Gg + <25 % N to R + >25 % N to W. Adoption of RRI + GGI over 3.64m ha area under RWC system of studied ecology may save 45.1 million US $ worth N fertilizer annually in addition to substantial reduction in air pollution.