Intercropping in Sugarcane Improves Functional Diversity, Soil Quality and Crop Productivity

Intercropping of mustard or potato in sugarcane in relation to traditional non-intercropping rotation on microbial diversity, soil quality and crop productivity was assessed in a 3-year cropping system trial. The systems consisted of sugarcane + mustard–ratoon–cowpea (SmRC), sugarcane + potato–ratoon–wheat (SpRW) and a standard sugarcane–ratoon–wheat (SRW) rotation. The SpRW system recorded a significantly higher cane equivalent yield (120.4 t ha−1) than SmRC (109.4 t ha−1) and SRW (92.6 t ha−1), which was 10.1% and 30.0% greater, respectively. However, the highest microbial activities (microbial counts, microbial biomass carbon and nitrogen and basal soil respiration), soil enzymes, total carbon (TC) and nitrogen (TN), available N, Zn, Cu, Fe and cation exchange capacity (CEC) were recorded for SmRC system. The available K and S content were greater in SRW, while the highest average substrate oxidation rate was recorded in SmRC (0.00291 OD h−1), which was 14.1% and 7.58% more than that of SpRW and SRW systems, respectively. Moreover, SmRC significantly increased functional diversity indices and soil quality index. Total N, soil organic carbon, available P and S were identified as the key soil quality indicators, contributing 31.8, 30.9, 12.9 and 10.8% toward quality development, respectively. The highest functional diversity indices of microbial community, soil quality and crop productivity under intercropping are the result of greater SOC, TC, TN, microbial and enzymatic activities. In conclusion, intercropping of mustard or potato in sugarcane could be the way to increase crop productivity in limited land resources in subtropical areas of India.