干湿交替与秸秆添加对土壤氮动态的影响

Effects of drying-wetting cycles and straw addition on soil nitrogen dynamics

为提高土壤氮肥力和秸秆综合利用率,采用室内模拟控制试验探讨了干湿交替、秸秆添加及其交互作用对土壤有效氮含量及氮矿化速率的影响。结果表明:秸秆添加对土壤有效氮含量无显著影响,但二者的交互作用显著增加了土壤铵态氮、硝态氮及无机氮含量,分别约增加了67%,93%和86%;二者交互作用对土壤氨化速率和硝化速率影响显著,对净氮矿化速率无显著影响。随着干湿交替强度的增加,土壤铵态氮、无机氮含量及氨化速率显著增加,但土壤硝态氮含量、硝化速率和净氮矿化速率变化不显著。方差分离结果表明,干湿交替强度、干湿交替循环次数、秸秆添加三者间的交互作用对土壤有效氮含量及氮矿化速率的方差解释量最大,其次为秸秆添加。研究结果表明,干湿交替可能会促进秸秆添加下的土壤氮转化过程,进而引起土壤氮肥力增加。

To improve soil nitrogen fertility and utilization efficiency of straw,a lab incubation experiment was used to explore the effects of drying-wetting cycles,straw addition and their interaction on soil available nitrogen contents and nitrogen mineralization rates.Only straw addition did not significantly affect soil available nitrogen contents,but the interaction between drying-wetting cycles and straw addition significantly increased soil ammonium,nitrate and inorganic nitrogen contents by about 67%,93%and 86%,respectively.Such interaction significantly affected ammonification and nitrification rates,but exerted no significant effect on net nitrogen mineralization rates.Increasing with drying-wetting intensity,soil ammonium,inorganic nitrogen contents and ammonification rates significantly increased,but soil nitrate contents and nitrification and net nitrogen mineralization rates did not significantly change.The variance separation analysis showed that the interaction of drying-wetting intensity,drying-wetting cycles times and straw addition explained the largest part of variance in the available nitrogen and nitrogen mineralization rates,followed by straw addition.The results indicate that drying-wetting cycles may promote the soil nitrogen transformation after straw addition,which in turn could increase soil nitrogen fertility.