Reductive soil disinfestation promotes vegetable N uptake by regulating soil gross N transformation and improving the quality of degraded soil

Purpose Reductive soil disinfestation (RSD) has been widely applied to improve soil degradation, enhancing vegetable N uptake and productivity. However, its effects on interactions between vegetable N uptake and soil gross N transformation remain unclear. Methods Two degraded vegetable soils were treated with RSD and N-15 tracing pot experiments were conducted to quantify the effects of RSD on N cycling in vegetable-soil systems. Results Vegetable NH4+ and NO3- uptake rates were 1.0-6.5 times higher following RSD than CK, while soil gross N mineralization rates (M) ranged from 0.83-13.00 mg N kg(-1) d(-1), and were significantly higher than the CK (0.21-8.71 mg N kg(-1) d(-1)). Meanwhile, autotropic nitrification rate (O-NH4) increased by 1.7-4.2 following RSD, while NH4+ immobilization rates (I-NH4) were significantly inhibited by RSD in the presence of planting. This induced a decrease in (O-NH4 + I-NH4)/M, and increases in NH4+ retention times and production rates of soil NO3- following RSD. In addition, RSD improved the overall quality of the degraded soils (increasing the pH, and decreasing EC and NO3- contents as well as pathogen abundance), further promoting vegetable N uptake. Conclusion RSD promoted vegetable N uptake by regulating soil gross N transformation rates and improving the quality of degraded vegetable soil. However, NO3- production rates were enhanced following RSD, increasing the risk of NO3- leaching and gaseous N losses. N fertilizer management under RSD therefore requires further attention.