Study On Nutrient Distribution And Output Of Slopes In Yangji Chong Small Watershed

At present,soil erosion in Karst area is more serious.Most of Guizhou province belongs to karst mountainous areas.Soil erosion will inevitably bring a lot of nutrients into water bodies.Rainfall is one of the main factors leading to soil erosion in karst area.Rainfall leads to karst area.The loss of soil nutrients,causing the decline of soil fertility,causing eutrophication pollution in small watersheds,while small watersheds are the source of pollution in large rivers and large rivers.The large loss of nutrients in small watersheds will cause serious pollution in large rivers in large river basins..Therefore,this study takes the karst small watershed?Yangji Chong small watershed?as the research object,and studies the following three aspects:five different water conservation measures?water conservation forest community,cultivated land community,natural grassland community,control community and The distribution of soil nutrient in slope and vertical direction of runoff plots in Guolin Community?;the output characteristics of rainfall runoff nutrients in runoff communities under five different water conservation measures;and the nutrient output characteristics of Yangzi Chongxiao watershed research.Concluded as follow:?1?The output of the slope area Total nitrogen?TN?of the runoff plot is:cultivated land?6.714mg/l?>control plot?3.273mg/l?>fruit plot community?1.462mg/l?>water conservation forest plot?1.168mg/l?>natural grassland plot?1.032mg/l?;Total phosporus?TP?output is represented by cultivated land?0.238mg/l?>control plot?0.1747mg/l?>water conservation forest plot?0.0278mg/l?>The fruit forest community?0.0201mg/l?>Natural grassland community?0.0147mg/l?;?2?The main output form of nitrogen in the sheep watershed is mainly nitrate nitrogen.The cultivated land and control plots show that the Particulate nitrogen?PN?is relatively large,and the runoff plots with water conservation measures?water conservation forest plots and fruit forest plots?The main output form of N and natural grassland area is mainly Nitrate?NO₃^--N?.The output of phosphorus is consistent with the small watershed and the runoff plot,and the output forms are mainly Particulate phosphorus?PP?;?3?The contents of soil nutrients?total nitrogen,total phosphorus,available phosphorus,and alkali-soluble nitrogen?in runoff plots are concentrated in the middle of the slope and the lower part of the slope in different slope positions?upper slope,middle slope and lower slope?.The trend,in the vertical direction,shows a tendency for nutrients to gradually decrease as the depth of the soil increases.?4?The main output form of nitrogen in small watershed is NO₃^--N>PN>Ammonia nitrogen?NH₄⁺-N?,and the output form is mainly NO₃^--N.The main output form of phosphorus is mainly PP.NO₃^--N and PP accounted for 73.18%and 85.82%of the main forms of nitrogen output and TP,respectively.Under the action of heavy rain,the output of TN,NO₃^--N and TP in small watershed were 121.476,78.657 and12.133kg/d,respectively.