秸秆还田对紫色土坡耕地养分流失的影响

Effects of Returned Straw on Nutrient Loss from Slope Cropland of Purple Soil

通过对川中丘陵区不同施肥坡地径流、泥沙和养分流失的观测与测定分析，研究了紫色土坡耕地暴雨下的产流产沙特征和氮、磷养分流失特征。结果表明，秸秆还田显著影响雨季紫色土坡耕地土壤侵蚀和产流情况；相比单施化肥处理。秸秆还田的泥沙量减少了70％～82％．地表径流量减少了26％～31％，渗漏径流量增加了30％～52％。秸秆还田显著减少了N、P的流失．减幅为60％～76％；各处理P流失的强度顺序依次为：NPK〉RSD〉RSDNPK〉RSDNP〉RSDN，N流失的强度顺序为：NPK〉RSDN〉RSDNPK〉RSDNP〉RSD；地表径流损失是P的主要流失途径。颗粒态是地表径流中P的主要迁移形态．磷酸盐是地表径流中溶解态总磷的主要组成部分，渗漏径流中的PO4^3- -P／DTP显著下降。渗漏淋失是N的主要流失途径．硝态氮是渗漏液中N的主要迁移形态．地表径流中NO3^- -N／DTN较渗漏液略低，溶解态总氮在地表径流N流失中所占比例超过50％。

A field experiment was conducted to study the characteristics of nutrient loss in hilly area of central Sichuan basin. There were 5 kinds of fertilization systems： application of N＋P＋K （NPK）, straw returned to field alone （RSD）, straw ＋ N （RSDN）, straw ＋N＋P （RSDNP）, straw ＋N＋P＋K （RSDNPK）. Series water samples were collected from the different plots in each rainfall event. The results showed as follows： Returned straw significantly affected the soil erosion and runoff from slope cropland of purple soil. Compared with NPK, the sediment yield from the application with returned straw decreased by 70%- 82%, the surface runoff decreased by 26%-31%, and the leaching amount increased by 30%-52%. Returned straw significantly reduced 60%-76% of the total nutrient loss. There were significant differences in the losses of nutrient of various treatment plots. The order of phosphorus loss was NPK 〉RSD〉 RSDNPK〉RSDNP 〉 RSDN, and the order of nitrogen loss was NPK 〉 RSDN 〉 RSDNPK〉RSDNP〉 RSD. As to phosphorus, transported by surface runoff was the major way, and total particulate phosphorus was the major form in that way. PO4^3- -P is major form of dissolved total phosphorus in surface runoff. On the other hand, PO4^3- -P / DTP in leachate significantly decreased. As to nitrogen, transported by leaching was the major way, NO3^- -N was the major form in leachate and there was not a same situation in surface runoff.