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为了明确土壤氮素转化对免耕和稻草还田的响应,研究了不同耕作对土壤(0～5 cm、5～12 cm和12～20 cm土层)氮素转化强度和铵态氮含量的影响。结果表明,免耕显著提高0～5 cm土层土壤氨化强度和铵态氮含量,但对于5～12 cm和12～20 cm土层趋势则相反;各土层土壤硝化势、反硝化强度免耕明显低于常耕,表明免耕促进0～5 cm土层有机氮的氨化作用和降低5～20 cm土层有机氮的氨化及0～20 cm土层土壤硝化-反硝化损失。稻草还田对土壤氮素转化强度的影响因耕作而异,免耕下,稻草还田促进5～20 cm土层土壤氨化强度及各土层反硝化强度和铵态氮含量,对0～5 cm土层土壤氨化强度和各土层土壤硝化势影响不大;常耕下,稻草还田降低5～20 cm土层铵态氮含量和硝化势,提高各土层氨化强度和反硝化强度。因而,免耕结合稻草还田更有利于土壤氮素的释放、供应,但需注意防止反硝化损失。
In order to clarify the response of soil nitrogen transformation to no-tillage and straw returning, the effects of different tillage treatments on nitrogen transformation intensity and ammonium nitrogen content in soils (0 ~ 5 cm, 5 ~ 12 cm and 12 ~ 20 cm soil layers) influences. The results showed that no tillage significantly increased soil ammonification intensity and ammonium nitrogen content in 0 ~ 5 cm soil layer, but reversed the trend in 5 ~ 12 cm and 12 ~ 20 cm soil layers. Soil nitrification potential, denitrification intensity No-tillage was significantly lower than that of normal tillage, indicating that no-tillage promoted the ammonification of organic nitrogen in 0 ~ 5 cm soil layer and decreased the ammonification of organic nitrogen in 5 ~ 20 cm soil layer and nitrification-denitrification loss in 0 ~ 20 cm soil layer . The effect of rice straw returning to soil N transformation intensity varies with farming. Under non-tillage and straw returning, the soil ammonification intensity and soil denitrification intensity and ammonium nitrogen content in 5 ~ 20 cm soil layer were increased, Soil amination intensity of 5 cm soil layer had little effect on soil nitrification potential of soil layers. Under normal conditions, straw addition of straw reduced soil ammonium nitrogen content and nitrification potential in 5-20 cm soil layer, Nitrification strength. Therefore, no-tillage combined with rice straw is more conducive to soil nitrogen release and supply, but should pay attention to prevent the loss of denitrification.