夜间增温对免耕农田土壤氮矿化与硝化速率的影响

摘要

Open field nighttime warming system was designed to investigate the effects of long-term nighttime warming and successive no-tillage on inorganic nitrogen ( N) and mineralization and nitrification rates in the cropland soil. The experi-ments were conducted with four treatments:normal nighttime temperature with traditional tillage ( CK) , nighttime warming with traditional tillage (W), normal nighttime temperature with no-tillage (NT), and nighttime warming with no-tillage ( WNT) . Compared to CK, alkali-hydrolyzable N and ammonium N remarkably increased under W treatment, which were increased by 26% ~28% and 82% ~133%, respectively in January and February. In the incubation experiments, miner-alization and nitrification rates increased significantly in warming treatments. Under NT treatment, soil average alkali-hydro-lyzable N and ammonium N contents were increased by 15% and 41%, respectively than those of CK, while mineralization rate was significantly highter and nitrification rate was significantly lower in NT than those in CK and W treatments. For WNT treatment, mineralization rate was higher than that in NT treatment, nitrification rate was lower than those in CK and W treatments. Thus, it was concluded that no-tillage could facilitate mineralization process of organic N in cropland soil, inhibit nitrification process, and hence reduce the risk of N loss.%研究了农田土壤氮矿化速率和硝化速率对长期夜间增温和免耕的响应特征。试验设置4种处理：常温＋翻耕( CK)、夜间增温＋翻耕( W)、常温＋免耕( NT)、夜间增温＋免耕( WNT)。与对照相比， W处理下土壤中碱解氮和铵态氮明显增加，其中1~2月增幅分别为26％~28％和82％~133％，且土壤氮矿化速率和硝化速率均显著高于CK处理。 NT处理下，土壤碱解氮和铵态氮的季节均值分别提高了15％和41％；土壤氮总矿化速率显著高于CK和W处理，硝化速率则显著低于CK和W处理。 WNT处理下的土壤氮矿化速率显著高于NT处理，而硝化速率则显著低于CK和W处理，可见，在夜间增温条件下，采取免耕措施将有利于土壤有机氮的矿化过程，降低了土壤硝化速率，从而减小了土壤氮素损失的风险。