Effects Of Soil And Water Conservation Measures On Soil Organic Carbon And Total Nitrogen In The Rocky Mountain Areas Of North China

Northern rocky mountain area is one of the important type areas of soil erosion,soil carbon and nitrogen loss caused by water erosion resulted the soil degradation and regional non-point source pollution.As the most important measure to control runoff,sediment yield and soil erosion,soil and water conservation measures have a significant influence on the input and output of soil elements.In order to study the effects of soil and water conservation measures on soil organic carbon and total nitrogen in northern rocky mountain area,explore more effective soil and water conservation measures to avoid soil nutrient loss,furthermore,it provides reference and ideas for the study of soil nutrient effects of typical soil and water conservation measures in the northern earth-rock mountainous areas,and provides basis for the prevention and control of non-point source pollution caused by soil erosion in this area,in this paper,we selected the runoff plots of typical northern rocky mountain area,Baima small watershed in Pingshun county,Changzhi city,Shanxi Province as the sample plot of water and soil conservation measures,The classification of plots mainly includes:?grassland measure runoff plots:Natural grassland runoff plot,runoff plot of sowing Bothriochloa ischaemum in drill;?plant+engineering measure runoff plots:Runoff plots of fish scale pits planted with different plants(fish scale pit of rosa davidiana,fish scale pit of hickory,fish scale pit of oriental arborvitae),platycladus orientalis runoff plots with different engineering measures(platycladus orientalis horizontal ditch,platycladus orientalis horizontal step,platycladus orientalis terraced on slopes,platycladus orientalis stone dike terrace),soil organic carbon and total nitrogen content in typical soil and water conservation measures in runoff plot were studied.The main conclusions of this paper are as follows:(1)Different soil and water conservation measures have significant effects on SOC(P<0.05),among the grassland measures,white leymus drilling(26.13g · kg-1)is more suitable for the protection of organic carbon on the slope.The organic carbon condition of natural weeds on the whole slope is the best(24.86g · kg-1),it was 113.41%of the runoff plot without measures;different plant measures(fish scale pit),yellow rose is most suitable for the protection of soil organic carbon on the slope(27.37g·kg-1),organic carbon(25.04g · kg-1)content in the whole soil of platycladus orientalis is the highest,it was 114.23%of the runoff plot without measures;among the different engineering measures(platycladus orientalis),the organic carbon content in the whole soil of horizontal step is the highest(33.33g · kg-1),and that in the stone dike terrace is the worst(18.19g · kg-1),they were 152.05%and 82.98%respectively in non-measure runoff plots,and with significant difference(P<0.05).Based on the nine measures,the most suitable soil and water conservation measures for the accumulation of SOC is coniferous tree horizontal step.(2)Different soil and water conservation measures had significant effects on soil TN(P<0.05).Among the grassland measures,the natural weeds had the best overall nitrogen condition(2.09g · kg-1),it was 115.47%of the runoff plot without measures.Among the different plant measures(fish scale pit),the TN content in the whole slope of platycladus orientalis runoff plot was the highest(2.13g · kg-1),it was 117.68%of the runoff plot without measures,which was significantly different from the other three measures(P<0.05);in different engineering measures(platycladus orientalis),the horizontal step soil TN content was the highest(2.21 g · kg-1)and stone dike terrace runoff plot was the worst(1.53g · kg-1),they were 122.01%and 84.53%respectively in non-measure runoff plots.According to the accumulation of TN in soil,the most suitable soil and water conservation measure is coniferous tree horizontal step.(3)The regularity of organic carbon content in 0-10 cm topsoil and 0-30 cm soil was com-paratively consistent,among different soil and water conservation measures.Therefore,surface soil can be used as an important index to compare the soil organic carbon content of different land use types,but the consistency of soil total nitrogen was low.