Green Manure-Based Nitrogen Management in Rice and Zero Tillage in Succeeding Toria and Sweet Corn Sustain System Yield and Soil Quality in Eastern India

Rice-based cropping systems are the predominant sources of livelihood for farmers in South Asia, where soil quality decline is a major concern. An experiment was conducted at Bhubaneswar, Odisha, India, in 2018-2019 and 2019-2020. It comprised two rice cultivars, 'Manaswini' (M) and 'Hasanta' (H), and three nitrogen management practices-100% soil test-based nitrogen (STN) (N100), 75% STN + in situ green manuring (Sesbania) (N75+GM), and 50% STN + green manuring (N50+GM)-in the main plot. Meanwhile, sub-plots consisted of three tillage methods for succeeding toria-sweet corn, namely zero tillage (ZT), conventional tillage (CT), and a furrow-irrigated raised bed (FIRB). The experiment was laid out in a split plot design with four replications to assess system nutrient uptake, productivity, and soil quality. Both rice cultivars were equal in terms of system nutrient uptake. The N75+GM practice recorded the highest system NPK uptake (304.1, 70.34, and 343.5 kg ha-1, respectively), enhancing the system N uptake by 10.7 and 7.4%, P uptake by 18.8 and 12.2%, and K uptake by 9.8 and 9.6% over N100 and N50+GM, respectively. ZT recorded the highest system NPK uptake (299.9, 70.6, and 339.7 kg ha-1, respectively). The most promising treatments, M+(N75+GM)-ZT and H+(N75+GM)-ZT, recorded the maximum system economic yield (10.72 and 10.64 t ha-1), residue yield (22.36 and 21.98 t ha-1), biological yield (33.07 and 32.63 t ha-1), and relative soil quality index (0.84 and 0.91). Correlation and principal component analyses exhibited positive and close relationships between all biological yield and soil quality parameters, except for micro water-stable aggregates, the fungal population, and the bulk density. The application of N75+GM in M or H rice and ZT in succeeding toria-sweet corn can sustain productivity and soil quality in Eastern India.