Influence of Water Management Farming Practices on Soil Organic Carbon and Nutrients: A Case Study of Rice Farming in Kilombero Valley, Tanzania

Abstract

Water scarcity and nutrient availability for rice farming have become great matters of concern in the contexts of climate change and land use change globally. Both interact and contribute to crop productivity at the expense of nutrients and future water sustainability. The objective of this study was to understand the on-farm potential response of soil organic carbon (SOC), total nitrogen (TN), and total phosphorous (TP) to water management practices in rice farming within the Kilombero Valley, Tanzania. Soil samples were collected from three villages in the study area at four depths: 0–20, 20–30, 30–40, and 40–50 cm. Four water management regimes, namely: A = traditional flooding (rainfed) without intensification of rice farming; B = traditional flooding (rainfed) involving a system of rice intensification (SRI); C = alternative wetting and drying (AWD) involving SRI for one cropping season; D = abandoned fields (fallow); and E = AWD involving SRI for two cropping seasons, were investigated as regards their impact on SOC, TN, and TP. There were significant (p < 0.05) effects of water management regimes on SOC, TN, and TP. AWD involving SRI for one cropping season indicated a positive effect on SOC and TN across all depths as compared to other practices. We conclude that water management practice that involves AWD with SRI for one cropping season is a plausible approach to maintaining high SOC and TN, with the potential for increasing crop production while minimizing water consumption.