The Research Of Soil Nutrient Change Characteristics Of Slope Under Soil And Water Conservation Measures

The black soil area was under the plough extensively,but there was no comprehensive and effective measures to prevent and control soil degradation,which would lead to soil erosion.And a large amount of sediment,nitrogen,phosphorus,pesticides and other non-point source pollutants join the receiving water.Finally,this has taken river water quality deterioration,lake eutrophication and other environmental problems.Therefore,it is necessary to actively explore the soil erosion control technology based on the surface source pollution control to strengthen the management of non-point source pollution and ensure the safety of regional water quality.This paper selected soil and water conservation measures(SWCMs)system composed of water conservation forest,level terrace and hedgerow,the corresponding control areas(CAs,no measures slope farmland)and the planting hedgerow with different width as the research object.Using GPS to locate the point sampling and combining traditional statistical analysis and ArcGIS’s statistical analysis,through the comparison of parameters and error values,the best spatial interpolation model(spherical model)and Kriging were selected to map spatial distribution of soil properties and to study soil nutrient spatial variability of SWCMs system and no measures slope farmland.Simultaneously,in order to construct the less investment,rapid,good economic returns hedgerow,this research would cultivate the hedgerow of different width,set up different sampling points and stratify sampling to study the effects of hedgerow on soil fertility of short farmland at the study area.The conclusions are as follows:(1)With soil depth increasing,the content of SOM,TN,TP and Olsen-P decreased.The spatial variability of four indicators is contrasted,which is TP>Olsen-P>TN>SOM.Their spatial variability of TN,TP and Olsen-P were significantly affected by SWCMs,while SOM was related with not only non-human factors,but also human factors.The use of Kriging interpolation mapping showed that the five indicators were unevenly distributed in the space.After taking conservation measures,the content of soil nutrient was significantly higher than that of the control area.From the top of the hill to the bottom of the slope,soil nutrient was decreased regularity in CAs.Soil and water conservation forest interception effect on TN,TP and SOM are the best,and the interception effect of level terrace of Olsen-P is significant.As a result of plants with terrace as a necessary part of the loss of soil nutrients,there were enchiment of soil nutrient,showing the effect of hedgerow on nutrient retaining function is not significant.By statistical analysis,the coefficient of variation of SOM and TN at 0-15 cm in SWCMs area was greater than that in CAs,but the variation coefficient of TP and Olsen-P was opposite to that.The coefficient of variation of SOM,TN,TP and Olsen-P at 15～30 cm in CAs were greater than that of SWCMs system.There was a significant positive correlation between SWCMs and soil nutrient content at different depths,and TN and Olsen-P of 15～30 cm were significantly positively correlated with them of 0～15 cm,but the other indicators of 0-15 cm and 15～30 cm were positively correlated with each other.The contents of SOM,TN,TP and Olsen-P in different depths increased and then decreased with the change of the month,but the degree of change was different because of different SWCMs.(2)There was a relationship among the hedgerow width and SOM,Olsen-P.The wider hedgerow arranged in uphill position could produce better effect that Olsen-P can be distributed uniformly in the hedgerow nearby.The content of SOM and Olsen-P are more and more abundent in the top sample sites of hedgerow.But there were strong erosion in the simpling sites of the middle of hedgerows and the bottom of hedgerows.With the effect of hedgerow,SOM and Olsen-P’s changes were larger in the 0～15 cm layer,while SOM and Olsen-P became smaller in the middle sample sites of hedgerow in 15～30 cm layer.Hedgerow can change microtopography of the slope,and the 0～15 cm layer’s content of SOM and Olsen-P are more and more abundent in the top sample sites of hedgerow and are the highest,while the middle sampling sites’ content of hedgerow are highest in the 15～30 cm layer.SOM were strong loss in the slope,and Olsen-P is highly concentrated.Therefore,planting grass hedgerow should consider suitable width and select the appropriate plant species.And people should strengthen management and protection of hedgerow,so as to improve the overall land productivity.