【摘要】 利用长期定位试验探讨了施氮磷肥、秸秆还田和不同耕作方式下长期不施钾肥对土壤速效钾变化及其对作物产量的影响。结果表明:长期不施钾肥土壤速效钾处于下降趋势:30年内耕层(0~20 cm)土壤速效钾含量降低了26.46%~54.64%,年均降低0.88%~1.82%;而亚耕层(20~40 cm)降低了10.66%~42.22%,年均降低0.36%~1.41%。在前15年(1985~2000年)土壤速效钾含量减少的速度较缓慢,而中10年(2000~2010年)则较快,2010年以后则较为平缓。长期不施钾肥、但同时施用氮磷肥将促进作物对土壤钾素的消耗;较高作物产量可导致速效钾的大量减少,而单施氮肥或磷肥处理的土壤速效钾含量变化较小。秸秆还田缓解了土壤钾素的减少,但对弥补土壤钾素的亏损作用很小。免耕相对于秸秆覆盖还田和秸秆翻耕还田对土壤钾素亏损的影响较少,但因其作物产量较低,秸秆翻耕还田较有利于作物产量的提高。更多还原

【Abstract】 The changes of soil available potassium(K) and the effects of nitrogen and phosphorus fertilizer applications,straw returning and tillage on grain yield were studied in a long term fertilization experiment. The results showed that the contents of available K decreased with increasing treatment years in the null K fertilizer treatment and the contents decreased by 26.46%- 54.64% in the topsoil layer(0- 20 cm) with annual rate 0.88%- 1.82%, and by 10.66%-42.22% in subsoil layer(20- 40 cm) at annual 0.36%- 1.41% after 30 years. Available K decreased slowly in the earlier 15 years(1985- 2000 years), but changed more rapidly from 2000 to 2010, and smoothly after 2010. The long-term application of both N and P fertilizer without K fertilizer promoted the consumption of available K by crops and increased crop yields, which led to the reduction in available K content. However, the single application of N or P fertilizer had little effect on the available K content. Straw returning to the field did not offset the loss of soil K.Compared with straw mulching and plowing tillage combined with straw returing, no-tillage decreased the decline in available K content and crop yields. But, plowing tillage combined with straw returning was beneficial for grain production.更多还原