Preliminary Study On The Effect Of Gully Land Regulation On Soil Ecological Environment In Loess Hilly And Gully Region

Aiming at the soil ecological environment problems in the Loess Hilly and Gully Region,such as frequent slope water erosion disasters,serious soil and water loss and low soil quality of newly dam land,In yan’an sheepfold groove in the basin,a blind ditch of debris typical of underground drainage channel regulation engineering land as the research object,undisturbed basin for comparison,through combination of field sampling and laboratory analysis,system to explore,a blind ditch of debris of the underground drainage system of a typical complex system of channel regulation engineering of slope gully land soil ecological environment influence,mainly to the following conclusion:（1）Effect of soil erosion resistance on slope surface:In the slope with excavation rate of 7%,the average weight diameter of soil aggregates（MWD）and organic carbon content of soil aggregates increased first and then decreased with the slope position decreasing,while the control slope gradually increased.The MWD of the excavated slope was reduced by 6%-8%and 58%-73%respectively in the underslope area and the excavation area compared with the central slope area.The soil organic carbon content was significantly reduced by 8%-41%in the 0-80 cm soil depth in the underslope area,and by 10%-39%in the 0-40 cm soil depth in the excavation area,Soil aggregate fractal dimension D with the decrease of slope position,slope excavation slope,slope toe area under the slope does not change significantly,the central soil erosion can be Ks value with the decrease of slope position,slope excavation are angled trend of increase with the decrease of the first,which under the slope zone and slope excavation area compared with the central increase 4.8%5%,65%and 109.7%respectively,and contrast slope are gradually decreasing trend.The results showed that the soil organic carbon and water content were significantly affected in the underslope region than in the toe of slope region,while the soil structure and aggregate stability were significantly affected in the underslope region than in the toe of slope region.（2）Impact on slope erosion environment:Soil erosion can be Ks and soil aggregate MWDS and organic carbon content was significantly negative correlation,and the soil aggregate fractal dimension was significantly positively related,and with the increase of slope excavation rate,soil erosion can be Ks and fractal dimension D with the increase of the excavation rate between the correlation coefficient showed a trend of increase,and with the increase of excavation rate between organic carbon its correlation coefficient showed a trend of increase with the decrease of the first;After one year,the soil erodibility Ks value increased by 19.2%-49.0%,and the aggregate MWD value decreased by 10.2%-22.2%,respectively.Therefore,in the later slope protection process,not only the protection of the stability of the excavation area should be strengthened,but also the reduction of the soil erosion risk on the upper slope of the excavated slope should be paid attention to.According to the above relations,a revised formula for calculating the soil erodibility K value was established:K=（_S）*（-0.120）^-0.114ln+0.570)^-0.04)（3）Influence on soil quality of the new land:In the vertical direction,the new creation of closing with the increase of soil depth,the average soil water content and average the average organic carbon content,conductivity,average p H had no obvious change trend,and in the original closing and with the increase of soil depth,the average and the average soil water content,soil conductivity,soil p H value was positively related to relationship on average,are negatively related with soil organic carbon content;In the horizontal direction,the spatial variation coefficients of each index in the 0-200 cm soil layer of the newly constructed dam are all smaller than those in the original dam.In the east-west direction,the soil water content,electrical conductivity and p H value of the newly constructed dam show a trend of<in front of the dam>behind the dam,and the organic carbon content shows a trend of<in front of the dam>behind the dam in the 80-200 cm soil layer.The soil water content and soil electrical conductivity of the original dam land showed the trend of the>dam in front of the dam and the>dam in behind.The soil organic carbon content in the 80-200 cm soil layer showed the trend of the front<the middle<the back of the dam,which was similar to the trend of the new dam land.The soil p H in the 0-60cm soil layer showed the trend of the middle<the front of the dam and the back of the dam,and the trend of the middle<the front of the dam and the back of the dam in the 60-200 cm soil layer.But the overall degree of variation is relatively small;From the north-south direction,the soil water content increased from south to north,and the soil organic carbon content decreased gradually.The variation trend of soil electrical conductivity and p H was not obvious from north to south.In the original dam land,the indexes were not obvious from north to south.This indicates that the typical trench land renovation project with blind gravel ditch underground drainage system can effectively drain soil water in the newly constructed land and reduce the moisture content and salinization degree of deep soil.（4）Environmental impact on newly-constructed soil quality:In both newly constructed and original land,soil conductivity increased significantly with soil water content,and there was a significant positive correlation between soil conductivity and soil p H value,while there was a significant negative correlation between soil organic carbon and soil p H value.This indicates that most of the water-soluble salts in soil are alkaline ions,and too high or too low water content is not conducive to the accumulation and storage of soil organic carbon.When the water content is distributed between 14%and 18%,the soil organic carbon content is the highest.