秸秆覆盖与平衡施肥对巢湖流域农田氮素流失的影响研究

通过野外径流小区观测试验,研究了巢湖流域旱地秸秆覆盖与平衡施肥条件下的径流、泥沙和氮素流失特征。结果表明,相对于当地传统耕作区,秸秆覆盖和平衡施肥能分别减少30.47%和21.61%的径流量,减少22.88%和20.59%的泥沙量,表现出显著的水土保持作用。当地传统耕作处理氮向水体迁移的负荷量为3.04 kghm-2,流失系数为1.35,其中溶解态氮是氮迁移的主要形式,其浓度占总氮浓度的60%~88%。秸秆覆盖与平衡施肥均能有效的降低径流氮的流失量,可分别降低27.42%和21.88%的氮流失,但其对径流氮浓度的影响却不明显。作物生长情况显著影响土壤氮素的流失,地上部分生物量与径流总氮的迁移量呈负相关关系。因此秸秆覆盖和平衡施肥可以作为源头控制农田养分流失的较好措施加以推广。

Effects of Straw Mulch and Balanced Fertilization on Nitrogen Loss from Farmland in Chaohu Lake Region

A field experiment was carried out in Chaohu Lake Region to study the characteristics of nitrogen loss by runoff from farmland.Three treatments of conventional tillage(T),straw mulch(TS) and balanced fertilization(BF) were set up with three replications.Total nitrogen(TN),dissolved nitrogen(DN),particulate nitrogen(PN),NH4+-N and NO3——N were measured or calculated for the water samples.The results showed that compared with T treatment,the runoff of TS and BF decreased by 30.47% and 21.61% respectively,and the sediment decreased by 22.88% and 20.59% respectively,implying significant effects of balanced fertilization and straw mulch on soil and water conservation.The nitrogen loading and coefficient of surface runoff from farmland in T treatment was 3.04 kg hm-2 and 1.35 respectively.Dissolved nitrogen(DN) was the main form of nitrogen from surface runoff,accounting for 60%-88% of total nitrogen.Straw mulch and balanced fertilization could decrease 27.42% and 21.88% of nitrogen loss,but they had no significant influences on nitrogen concentration.The biological properties significantly affected the loss of nitrogen,and there was a negative correlation between the loss of nitrogen and the aboveground biomass.Therefore,straw mulch and balanced fertilization should be popularized in this area in order to control the agriculture non-point source pollution.