玉米田N_2O排放及减排措施研究

N_2O EMISSION IN MAIZE FIELD AND ITS MITIGATION

用封闭式箱法对玉米田Ｎ２Ｏ排放进行了全年、系统的原位观测，发现Ｎ２Ｏ排放有明显的季节变化，主要排放期是在作物的生长季节．另外，玉米植株能通过其根系的作用增加土壤向大气排放Ｎ２Ｏ．应用长效碳酸氢铵和缓释尿素于玉米田中，在施入等量氮的情况下，定时监测Ｎ２Ｏ排放量．结果表明，上述二种长效肥料与普通尿素和碳酸氢铵相比，能明显减少土壤中Ｎ２Ｏ排放，并能提高玉米产量．此外还发现，在玉米生长的后期，它们在土壤中仍然能保持较高含量的硝态氮和铵态氮，说明它们都能使肥料缓慢地释放到土壤中，供作物长期吸收利用，使作物吸收到足够的氮，同时它们的这一特殊作用也减少了土壤微生物的硝化和反硝化过程大量产生的Ｎ２Ｏ．因此，它们具有经济和环境双重效益并有着广阔的应用前景．

N_2O fluxes from maize field were measured systematically in situ for whole year using closed chamber technique. The results showed that N_2O emission has significant seasonal variation, and mainly occurs during the growing stage of crop. In addition, maize plant can stimulate N_2O production through the function of its root in soil. Compared with urea and ammonium bicarbonate, slow-releasing ammonium bicarbonate (ammonium bicarbonate + dicyandiamide) and slowreleasing urea (urea + hydroquinone + dicyandiamide) can not only reduce N_2O emission in maize field but also cause an increase of maize yield for 14%.