紫色土坡耕地不同施肥水平下泥沙中氮、磷流失特征

以紫色土坡耕地"冬小麦—夏玉米"种植模式为研究对象,通过设置对照处理、复合施用农家肥和化肥、单施化肥、单施化肥增加施肥量、单施化肥横坡垄作5种施肥水平,采用径流小区定点监测的方法,研究了紫色土坡耕地不同施肥水平下泥沙中氮、磷流失特征.结果表明:各施肥水平下土壤表层养分质量百分比有一定程度增加,泥沙养分均发生富集现象,横坡垄作养分富集比小于顺坡耕作,复合施用农家肥化肥有效养分富集比大于全量养分,单一施用化肥全量养分富集比明显大于有效养分,且养分富集比随施肥量增加而增大;各施肥水平下,泥沙流失仅占0.34～6.21%;磷素流失中泥沙流失占78.80～84.83%,磷素流失以泥沙为主.从相对流失系数来看:氮的流失系数由高到低依次为单施化肥、横坡垄作、单施化肥增加施肥量、复合施用农家肥和化肥;磷的流失系数从高到低依次为单施化肥增加施肥量、横坡垄作、单施化肥、复合施用农家肥和化肥.

CharacteristicsofNandPLossesinSedimentof PurpleSoilonSlopingFarmlandwithDifferentFertilizationLevels

In a "winter wheat-summer maize" system on sloping farmland of purple soil,five fertilization treatments were designed,i.e.CK,combined application of manure and fertilizer,chemical fertilizer alone,chemical fertilizer with increased fertilization rate and contour plowing with chemical fertilizer,and the runoff in plots was monitored to study the characteristics of nitrogen and phosphorus losses in the sediment.The results were as follows.Nutrient content of the surface soil increased to some extent,and nutrient enrichment occurred in the sediment regardless of fertilizer treatments.The available nutrient enrichment ratio of sediment was smaller in the horizontal(or contour) plowing treatment than in the vertical plowing treatment,the combined application of manure and fertilizer treatment having greater available nutrient enrichment ratio than total nutrient enrichment ratio,and the treatment of chemical fertilizer application alone having greater total nutrient enrichment ratio than available nutrient enrichment ratio.The nutrient enrichment ratio increased with increasing fertilization rate.In different fertilization treatments,sediment loss only accounted 0.34-6.21%;sediment loss accounted for 78.80-84.83% of total phosphorus loss,and phosphorus loss occurred mainly in the sediment.The treatment of chemical fertilizer alone had the greatest relative loss factor,followed in order by the treatments of contour plowing,chemical fertilizer with increasing fertilization and combined application of manure and fertilizer.The treatment of chemical fertilizer with increased fertilization rate had the greatest phosphorus loss coefficient,followed in sequence by the treatments of contour plowing,chemical fertilizer application alone and combined application of manure and fertilizer.