秸秆还田对紫色土坡耕地养分流失的影响

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PO43--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%。

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

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. PO~(3-)_4-P is major form of dissolved total phosphorus in surface runoff.On the other hand,PO~(3-)_4-P / DTP in leachate significantly decreased.As to nitrogen,transported by leaching was the major way,NO~-_3-N was the major form in leachate and there was not a same situation in surface runoff.