Crop Diversification in Rice-Based Agroecosystem: Medium-Term Effects on Soil Properties, Carbon and Other Nutrients' Stoichiometry, and System Productivity

Soil physical and chemical properties play salient roles in terrestrial nutrient cycling; particularly, how they respond to land use change combined with subsequent crop diversification is less understood, hindering the precise evaluation of soil nutrient dynamics and crop productivity. Therefore, the present study aimed to explore the extent to which the level of diversity of succeeding crops in a rice-based system can affect soil physicochemical properties, their interrelation with nutrient bioavailability, and total system productivity under tropical climatic condition. The soil was sampled from three depths, viz., 0-15 cm, 15-30 cm, and 30-45 cm, from plots of one uncultivated area and four different rice-based cropping systems subjected to the medium-term (7 years) crop diversification impact. Results revealed that increasing cropping practices (CP) and further inclusion of crop diversification under conventional system reduced the total soil organic carbon (SOC) content in the surface layer as well as deeper soil layers. Among cropping practices, the order of mineral N availability was CP1 (rice-fallow) > CP0 (uncultivated) > CP4 (rice-fallow/capsicum/baby corn/groundnut) > CP3 (rice-fallow/capsicum/mungbean) = CP2 (rice-fallow/okra/maize). Due to different crop diversifications, no significant effect was observed on available P at different depths. However, 17.3% lower exchangeable K was observed under CP4 compared to CP0. The order of total system productivity and production efficiency for diversified rice-based cropping practices was CP4 > CP3 > CP2 >> CP1. More diverse cropping systems using lesser inputs can improve the performances of agroecosystem to the better tune, rather than less diverse systems. However, in terms of both sustainable and profitable cropping system, CP4 is best suited as it has the potential to restore SOC in deeper layers and has the highest system productivity.