Characteristics Of Soil Erosion And Soil Nutrient Distribution Of Hedgerows Sloping Farmland

Purple soil is the main cultivation soil in the hilly region of Sichuan,over the years,unreasonable development and utilization and overexploitation have caused serious soil and water erosion and land degradation in sloping farmland,The serious soil and water erosion of sloping farmland calls for an urgent treatment.Hedgerows technology in sloping farmland is an effective plant measure to soil and water erosion in sloping fields.In this study,the hedgerows sloping farmland in Suining Soil and Water Conservation Experimental Station as the research object,based on the data of individual rainfall,runoff and sediment yield of hedgerows sloping farmland in Suining Soil and Water Conservation Experimental Station,combined with sediment sample and laboratory analysis,the effect of the Vetiveria zizanioides and Leucaena leucocephala hedgerows which has been planted from 2012 to the present were analyzed on runoff and sediment yield,microtopography,runoff nutrient loss and soil nutrient distribution in sloping farmland.The results showed that:The hedgerow could effectively reduce the runoff and sediment yield of sloping farmland.Hedgerow’s effects on sediment yield were better than that on runoff.The runoff depths and sediment yield of the control plots(plot CK1 and plot CK2)were significantly correlated with the average rainfall intensity and rainfall(P <0.01).In the hedgerows plots(plot ZX1,plot ZX2 and plot ZXH),the runoff depths and sediment yield were positively correlated with the average rainfall intensity and rainfall.Especially,there were highly significant correlations between runoff depths and rainfall.For three rainfall patterns,there were no significant differences in the runoff depths and sediment yield among different plot.The hedgerows effect of runoff and sediment reduction on rainfall A(short duration,heavy rainfall)was better than that on rainfall B(moderate duration,moderate rainfall)and rainfall C(long duration,light rainfall).After planting the hedgerows,there was sediment accumulation zone near hedgerow lines.The average slope of plot ZX1,plot ZX2 and plot ZXH turn to 11.97°,7.73°,and 7.89°from 15°,10°,and 10°,respectively.Finally,hedgerows make sloping farmland benching.The total potassium(TK)in all soil layers showed irregular changes.The soil organic matter(SOM),total nitrogen(TN)and total phosphorus(TP)in 0-20 cm soil layer were enriched on the top of hedgerows,while poorer below the hedgerows and between the hedgerows,which changed just as waves from slope crest to slope toe.Whereas in the control plots,these indexes showed constantly increased trend from slope crest to slope toe.The nutrient indexes of 20-30 cm soil layer showed irregular changes.In hedgerow plots,the soil SOM and TN decreased from 0-10 cm soil layer to 20-30 cm soil layer in turn,and reached a significant level(P<0.05).However the change trends of TP and TK were not obvious.Overall,compared with control plots,the SOM,TN and TK content increased significantly in hedgerow plots,especially in the 0-20 cm soil layer.But no effect for soil TP content.Meanwhile,SOM contents in Vetiveria zizanioides hedgerow plots were more than those of Leucaena leucocephala hedgerow plots.During a natural rainfall,the concentrations of nitrate nitrogen,ammonium nitrogen and phosphate in the control plots were higher than those in the hedgerow plot.The corresponding flow loss showed the same rule.The effect of hedgerows on reducing nitrate nitrogen,ammonium nitrogen and phosphate concentration and loss in surface runoff were significant.Altogether,the hedgerows could not only effectively reduce the sediment yield,improve the microtopography of sloping farmland,but also reduce the runoff nutrient loss and improve the soil nutrient content of the slope farmland.However,the effects of hedgerows on improving soil nutrient was different between different positions of slope and different nutrient indexes.Therefore,In the future management of sloping fields,the soil fertility should be strengthened below the hedgerows and between the hedgerows to maintain soil nutrient balance.