摘要
Reductive soil disinfestations (RSDs), as an alternative to chemical fumigations, have been widely applied to improve degraded greenhouse vegetable soils. However, high nitrous oxide (N2O) emission and nitrate (NO3 (-)) leaching would occur during RSD treatment. The aim of this study was to investigate the effect of pH on the removal of NO3 (-) and its transformed products during RSD treatment. @@@ A N-15 tracing incubation experiment was conducted in a degraded vegetable soil under 30 A degrees C for 360 h. There were five treatments: control (flooding only, noted as CK), flooding + alfalfa (RSD0), and RSD0 + lime at three application rates, which adjusted soil pH to 6.7, 7.7, and 8.4, noted as RSD1, RSD2, and RSD3, respectively. @@@ Increase in pH accelerated the removal of NO3 (-) under flooding condition, with the decrease in Eh. It took 120 and 72 h for RSD0 and RSD0 + lime treatments, respectively, when soil NO3 (-) content dropped from initial 147 to below 25 mg N kg(-1), but NO3 (-) content in the CK was still 32.1 mg N kg(-1) even after 360-h incubation. Liming inhibited dissimilatory NO3 (-) reduction to ammonium (DNRA) process and immobilization of NO3 (-) into organic nitrogen (N). After 360-h incubation, the ratios of N-15 transformed into NH4 (+) and organic N pools accounted for 0.46-1.20 % and 3.11-9.48 % of added (KNO3)-N-15 in RSD treatments, being lower than 2.17 and 16.8 % in CK, respectively. The ratio of cumulative N2O emissions to NO3 (-) disappeared from soil was greatly lower in RSD treatments (0.80-2.29 %) than in CK (5.20 %). @@@ RSD associated with liming accelerated the NO3 (-) removal and reduced the N2O emission but decreased the conversion rates of NO3 (-) to NH4 (+) and organic N.
- 出版日期2015-9
- 单位南京师范大学