不同耕种模式下降雨等级对紫色土坡耕地产流产沙的影响

Effects of rainfall levels on runoff and sediment yield of slope farmland in purple soil under different tillage and crop patterns

为了探讨紫色土坡耕地在不同降雨等级下的水土流失特征,为选择水土保持效应高的耕种模式提供依据,基于遂宁水土保持试验站1989—2016年降雨与径流输沙数据,划分4类耕种模式,就不同降雨等级下径流小区产流产沙规律进行分析。结果表明:1)小、中雨基本不造成侵蚀,侵蚀性降雨主要为大、暴雨,集中于6—8月。2)等高沟垄大雨下水土保持效应最好。相比顺坡垄作,横坡垄作大暴雨下可减流50%~56%,暴雨下减沙93%~95%,且差异显著(P<0.05)。顺坡垄作种植黄花较玉米可减沙88%~98%,大、暴雨下差异显著。植物篱定植初期产流产沙反而大于对照区,且在大雨下差异显著;而定植3年后,植物篱减流减沙作用明显,且香根草优于新银合欢。3)沟垄小区产流产沙量在特大暴雨与大、暴雨间差异显著。顺垄黄花小区产流量大,暴雨是大雨下的6.4倍,且差异显著;横(顺)垄小区大暴雨与大、暴雨的产沙量差异显著。定植初期植物篱小区产流量在各降雨等级间差异不显著(P>0.05),而油桃小区产沙量在大暴雨与大雨间差异显著。定植3年后植物篱及其对照小区产流产沙量在大暴雨与大、暴雨下均差异显著,大暴雨下产流量和产沙量分别为大、暴雨的3.3~6.6倍和8.8~113.5倍。各类措施减沙均优于减流效应,减沙作用随降雨等级增大呈降低趋势,考虑农业管理和经济收益,应结合实际情况选择适宜的耕种模式。

[Background]In order to select better tillage and crop patterns for soil and water conservation of slope farmland in the purple soil,the characteristics of soil and water loss were investigated.[Methods]Based on the data of rainfall,runoff and sediment yield from 1989 to 2016 at Soil and Water Conservation Experimental Station in Suining city,four periods were divided according to different patterns that include ridge and furrow tillage,economic and fruit forest,cross ridge and planting hedgerows.Runoff and sediment yield of different plots under different patterns were analyzed according to rainfall levels.[Results]1)Light rain and medium rain hardly caused soil erosion.The erosive rainfall was concentrated in June-August,which was mainly represented by rainstorm and heavy rain.2)The effect of contour ridge and furrow treatment was the most obvious under heavy rain.Compared with downhill ridge in farmland,cross ridge reduced runoff yield by 50%-56%under large rainstorm and reduced sediment yield by 93%-95%under rainstorm significantly(P<0.05).Compared with Zea mays,planting Hemerocallis citrina Baroni in downhill ridge significantly reduced sediment yield by 88%-98%under heavy rain and rainstorm.Runoff and sediment yield of planting hedgerows was bigger than that of the control plots in the initial stage of planting hedgerows,which was significantly different under heavy rain.However,after three years of planting,hedgerows had great effects of reducing runoff and sediment,and the effect of Vetiveria zizanioides was better than that of Leucaena leucocephala.3)Runoff and sediment yield of ridge and furrow plots during extraordinary rainstorm was significantly different from that during rainstorm and heavy rain.During large rainstorm,runoff yield of planting Hemerocallis citrina Baroni with downhill ridge was 6.4 times of that during heavy rain,and the difference was significant.The sediment yield during large rainstorm was significantly different from that during rainstorm and heavy rain in cross ridge and downhill ridge plots.At the initial stage of planting hedgerow,runoff yield of hedgerow plots was no significantly different from that of no-hedgerow plots during different rainfall levels(P>0.05).While sediment yield of Amygdalus persica hedgerow plots was significantly different from that of no-hedgerow plots during large rainstorm and heavy rain.Three years after planting hedgerow,runoff and sediment yield during large rainstorm was significantly different from that during rainstorm and heavy rain.The runoff yield during large rainstorm was 3.3-6.6 times of that during rainstorm and heavy rain,meanwhile,sediment yield during large rainstorm was 8.8-113.5 times of that during rainstorm and heavy rain.[Conculsions]Overall,sediment reduction effect of various tillage and crop patterns is better than runoff reduction effect.With the increase of rainfall level,the sediment reduction rate was decreasing.Therefore,considering the agricultural management and economic benefits,the appropriate patterns should be selected according to the actual situation of sloping farmland.