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

Abstract

• Rice residue incorporation and green gram was tested on yield and soil health. • Nitrogen fertilizer up to 75 kg ha −1 was saved by green gram growing before rice. • Sustainability was enhanced by rice residue and green gram incorporation. • Organic C increased by rice residue and green gram incorporation after 7 years. • Saving upto75 Kg N ha −1 in Punjab and Haryana could save $45.1 million yearly. Rice-wheat cropping system and associated residue burning is a major cause of air pollution and soil health depletion in Northern India. This calls for urgent technological interventions to address the issue and improve the profitability of this cropping system. Objective was to study the effect of rice residue incorporation (RRI) and green gram inclusion (GGI) on amount of N applied, productivity and soil health in rice-wheat cropping (RWC) system. Combinations of RRI, nitrogen management and GGI with conventional rice-wheat rotation were tested for 7 years. Eleven treatments with combination of RRI, RR removal, GGI and N management were evaluated. Treatment effects on system productivity, profitability and soil health parameters were measured. Treatment R-W (-RR) - Gg + <25 % N to R and R-W (+RR) - Gg+ <25 % N to R +>25 % N to W produced maximum rice (7677 kg ha −1 ) and wheat yield (5949 kg ha −1 ), though non-significant (P > 0.05) compared to control (Rice = 7508 & Wheat = 5724 kg ha −1 ). Nitrogen fertilizer up to 75 kg ha −1 was saved when GGI was taken up before rice. GGI and RRI was sustainable in terms of higher sustainability value index (SVI = 0.78), wheat equivalent yield (WEY = 20.0 t ha −1 ) and production efficiency (PE = 57.5 kg ha −1 day −1 ). The treatments with GGI + RRI produced 1015$ additional net returns with more than double B:C ratio. Soil health in the form of SOC (0.42 %) and available N (152.6 kg ha −1 ) 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 3.64 m 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.