Conservation Agriculture Based Integrated Crop Management Sustains the Maize–Wheat Rotation of North-Western India: Five Years’ Impacts on Crops and Water Productivity, Economic Profitability, Sustainable Yield Index and Soil Properties

Abstract We have evaluated eight different integrated crop management (ICM) modules for five years in a maize-wheat rotation (MWR); wherein, ICM1&2- ˈbusiness-as-usualˈ (conventional flatbed maize and wheat, ICM3&4- conventional raised bed (CTRB) maize and wheat without residues, ICM5&6- conservation agriculture (CA)-based zero till (ZT) flatbed maize and wheat with the residues, and ICM7&8- CA-based ZT raised bed maize and wheat with the residues. Results indicated that the ICM7&8 produced significantly (p<0.05) the highest maize grain yield (5 years av.) which was 7.8-21.3% greater than the ICM1-6. However, across years, the ICM5-8 gave statistically similar wheat grain yield, and was 8.4-11.5% greater than the ICM1-4. Similarly, the CA-based residue retained ICM5-8 modules had given 9.5-14.3% (5 years av.) greater system yields in terms of maize grain equivalents (MGEY) over the residue removed CT-based ICM1&4. System water productivity (SWP) was the highest with ICM5-8, being 10.3-17.8% higher than the ICM1-4. Nevertheless, the highest water use (TWU) was recorded in the CT flatbed (ICM1&2), ~7% more than the raised bed and ZT planted crops with or without the residues (ICM4-8). Furthermore, the ICM1-4 had produced 9.54% greater variable production costs compared to the ICM5-8, whereas, the ICM5-8 gave 24.3-27.4% additional returns than the ICM1-4. Also, different ICM modules caused significant (p<0.05) impacts on the soil properties, such as, organic carbon (SOC), microbial biomass carbon (SMBC), dehydrogenase (SDH), alkaline phosphatase (SAP) and urease (URE) activities. In 0.0-0.15 m soil profile, residue retained CA-based (ICM5-8) modules registered a 7.1-14.3% greater SOC and 10.2-17.3% SMBC than the ICM1-4. The sustainable yield index (SYI) of MWR was 13.4-18.6% greater under the ICM7&8 compared to the ICM1-4. Hence, this study conclude that the adoption of the CA-based residue retained ICMs in the MWR could sustain the crop yields, enhance farm profits, save water and improve soil properties of the north-western plan zones of India.