Impact of long-term drip irrigation on soil organic carbon and nutrient stocks in arid oasis farmlands

Water scarcity in arid regions necessitates efficient irrigation strategies to maintain agricultural productivity. While drip irrigation is increasingly adopted as a more water-efficient alternative to flood irrigation, its longterm impacts on soil properties, particularly on soil organic carbon (SOC) and nutrient dynamics, remain insufficiently explored. This study addresses this gap by investigating the effects of conversion from flood to drip irrigation on SOC pools and nutrient stocks in typical oasis farmlands of northwest China. We employed paired sampling and space-for-time substitution methods to assess soil profiles (0-100 cm) under different durations of drip irrigation (3, 5, 8, and 13 years). Soil organic carbon stocks (SOCS), nitrogen stocks (NS), and phosphorus stocks (PS) were quantified, along with the analysis of general physicochemical properties. Results indicated that SOCS decreased by 19.3 %, NS by 15.5 %, and PS by 12.2 % following the conversion, with the most significant reductions observed in the 20-40 cm soil layer. Additionally, the soil C:N ratio declined, while the C:P and N:P ratios increased. Regression analysis showed a significant negative correlation between the duration of drip irrigation and changes in SOCS and NS. Our findings highlight that conversion from flood to drip irrigation can lead to significant reductions in SOC and nutrient stocks. The trend becomes more pronounced with prolonged use of drip irrigation, underscoring the need for effective conservation practices to sustain soil health and productivity in arid regions. Implementing suitable management strategies in long-term drip-irrigated farmlands is necessary for maintaining agricultural sustainability.