TY - GEN A1 - Wang, Guan A1 - Zhu, Zihong A1 - Cao, Jianhua A1 - Zhu, Tongbin A1 - Zhou, Jinxing A1 - Müller, Christoph A1 - Li, Junran A1 - Freese, Dirk A1 - Le Roux, Xavier T1 - Agricultural cultivation duration affects soil inorganic N turnover and supply capacity : Evidence in subtropical karst regions T2 - Agriculture, Ecosystems & Environment N2 - The conversion of indigenous woodlands to agricultural lands has significantly altered nitrogen (N) cycling, impacting both ecosystem productivity and environmental health locally and globally. The relationship between cultivation duration and soil N availability and the mechanisms that drive these changes, however, remain unclear. In this study, we aimed to investigate how the duration of agricultural reclamation influences soil N cycling in the karst landscapes of southwestern China. We selected economic crops that have been cultivated for 1, 5, 15, and 30 years and conducted a regional survey using 15N labeling and molecular biology techniques to assess the effects of cultivation duration on soil N cycling. Our results show that short-term reclamation (< 5 years) caused minimal changes in soil N dynamics, with little effect on the net production rates of NH4+ and NO3–. However, as cultivation duration increased, we observed progressive declines in mineralization, nitrification, and microbial immobilization rates of NH4+ and NO3–. This led to a substantial reduction in soil inorganic N availability (–39 % for NH4+ and –70 % for NO3–) and a significant increase in the mean residence time of NH4+ and NO3–, indicating a slower N turnover. Long-term reclamation (30 years) resulted in the most pronounced effects, reducing the soil’s capacity to supply inorganic N by impairing soil organic matter input, degrading soil structure, and lowering soil pH. Key soil variables such as soil organic carbon content, pH, total N, and soil aggregate stability explained over 80 % of the variance in N turnover rates. Overall, our findings suggest that while shortterm reclamation has little impact, long-term agricultural practices significantly impair soil N cycling and availability. Sustainable agricultural practices that enhance soil organic matter content and promote soil aggregate stability could help preserve soil health and maintain productivity in karst and similar regions worldwide. Y1 - 2025 U6 - https://doi.org/10.1016/j.agee.2024.109462 SN - 0167-8809 VL - 381 PB - Elsevier BV ER -