Reductive soil disinfestation promoted vegetable N uptake by regulating soil gross N transformations and improving the quality of degraded vegetable soils

Abstract

Aims Reductive soil disinfestation (RSD) has been widely applied to improve soil degradation, thereby enhancing vegetable N uptake and subsequently productivity. However, the effect of RSD on interactions between vegetable N uptake and soil gross N transformation remain unclear. Methods Two degraded vegetable soils were treated with RSD. Untreated soils served as control (CK). To quantify the effects of RSD on N cycling in vegetable-soil systems, 15N tracing pot experiments were conducted. Results Vegetable NH4+ and NO3− uptake rates were 1.0–6.5 times higher in RSD treatments than CK. Soil gross N mineralization rates (M) in RSD ranged from 0.83 to 13.00 mg N kg− 1 d− 1, and were significantly higher than in CK (0.21 to 8.71 mg N kg− 1 d− 1). Autotropic nitrification rates (ONH4) increased by 1.7–4.2 times after RSD. NH4+ immobilization rates (INH4) were significantly inhibited by RSD in the presence of vegetables. These induced decreasing (ONH4 + INH4)/M, increasing NH4+ retention times and production rates of soil NO3− after RSD treatment. Thus, RSD promoted N supply to vegetables and subsequently N uptake by vegetables on degraded soils. In addition, RSD improved the quality on degraded soils (i.e. increasing soil pH, and decreasing soil EC and NO3− contents and pathogen abundances), which could also be an important factor promoting vegetable N uptake. Conclusion Thus, RSD can promote vegetable N uptake by regulating soil gross N transformations and improving the quality of degraded vegetable soils. However, N fertilizer management still needs attention because of stimulated NO3− production rates after RSD, which may lead to more rapid NO3− leaching or gaseous N losses.