Designing resource efficient integrated crop management modules for direct seeded rice-zero till wheat rotation of north western India: Impacts on system productivity, energy-nutrient-carbon dynamics

Eight integrated crop management (ICM) practices were evaluated for six years consecutively, which are ICM1&2: 'business-as-usual' (conventional transplanted rice fb flatbed wheat), ICM3&4: conventional direct seeded rice (DSR) fb furrow irrigated raised-bed wheat without residues, ICM5&6: conservation agriculture (CA)-based zero-tilled (ZT) DSR fb ZT wheat with the wheat and rice residues and ICM7&8: CA-based ZTDSR fb ZT wheat with the wheat, mungbean and rice residues. ICM7-8 produced 9.6-16.4% and 9.4-9.9% greater system rice equivalent yield (REY) than the ICM1-4 and ICM5-6, respectively. Residue-retained CA-based ICM5-8 had 23.2% and 58.5% greater N and P balance, respectively, than the residue removed (ICM1-4); subsequently, negative K balance (-53 to -115.5 kg ha(-1)) was recorded in ICM1-4. ICM5-8 consumed similar to 60-78% of total energy and produced the highest energy output (E-o) in rice (11.5-12.6%)/wheat (7.3-13%) than ICM1-4. In contrast, ICM1-4 had a greater energy use efficiency (EUE) compared to ICM5-8 due to lesser energy input (EI) through indirect renewable sources. At a soil depth of 0.0-0.45 m, the ICM5-8 contributed 7.9% and 20.2% greater active and passive OC pools over the ICM1-4. Thus, CA-based ICM in rice-wheat rotation (RWR) could be a possible substitute for the positive nutrient balance, system yields and energy and carbon dynamics.