| Taking the coal mining subsidence area in Jining as the research area,this paper collected soil samples by field investigation and analyzed the variation of soil organic carbon before and after collapse and its relationship with other physical and chemical properties,and grasps the soil organic carbon and other soil physical and chemical properties at different positions(slope top,slope,slope bottom and water accumulation area)and different depths of the subsidence area.The relationship between the distribution characteristics of the soil and the physical and chemical properties of soil organic carbon and other soils is expected to provide a scientific basis for the management of agricultural production and the sustainable utilization of soil in the subsidence area.The results of the study show that:(1)Distribution characteristics of soil organic carbon in the subsidence areaAt different slope positions,soil organic carbon presents a trend of migration from the top of the slope to the edge of the accumulated water,which first decreases and then rises,and tends to change in the center of the collapse.Compared with the non subsided land,the SOC content in the soil was significantly reduced by 20.3%(p<0.05).The soil organic carbon content in slope and middle slope position was significantly different from that in the non subsided land(p<0.05).In different depths,soil organic carbon content decreased with the depth of soil profile,the content of soil organic carbon was mainly concentrated in 0 ~ 20 cm soil layer,accounting for 65.9% of the whole soil layer(0 ~ 60cm),obviously higher than the soil organic carbon content(p<0.05)at all levels below 20 cm,and the soil organic carbon content of each soil layer was lower than that of no collapse.Soil organic carbon content at the corresponding level of subsidence.On the different slopes,the average spatial variation coefficient of soil organic carbon is 11.9%,which belongs to the medium variation intensity.The spatial variation of the spatial variation coefficient is: in the slope > the bottom of the slope > the top of the slope > the water accumulation edge,the spatial variation coefficient 15.9% of the position in the slope is the maximum,which is obviously higher than the upper slope and the downhill,indicating that the soil nature fluctuates relatively large and is subsided by mining.The influence is great.The spatial variability coefficient of soil organic carbon is 13.1%,and is moderate variation intensity at different depths.The minimum spatial variation coefficient appears in 20 ~ 40 cm soil layer 4%,the maximum value appears in 40 ~ 60 cm soil layer 24.7%.The spatial variation coefficient of soil organic carbon in the 0 ~ 20 cm soil layer is greater than 20 ~ 40 cm soil layer,the latter is less than 40 to 60 cm soil layer,and the spatial variation coefficient of soil organic carbon in the bottom soil layer is the largest,and the soil property spatial variability is larger Soil organic carbon content fluctuates greatly,and is affected by coal mining.On the whole,the spatial variability coefficient of soil organic carbon in the study area is larger than that in the bottom soil layer,and is greatly influenced by mining.This is consistent with the distribution of soil organic carbon content on different slope positions and depths,indicating that the spatial variability intensity will affect the nutrient content.(2)Distribution characteristics of soil physical and chemical properties in the subsidence areaThe soil bulk density increased from the top of the slope to the center of subsidence and increased the bulk density with the depth of the subsidence.The coal mining subsidence made the soil tight and the bulk density increased,and the soil water content and bulk density in the subsidence area had a similar trend,because the water was lost from top to bottom and affected by the subsurface submersible position along the subsidence slope.The soil moisture content of the soil increased,and the soil pH value of the subsidence area increased gradually along the subsidence slope.With the increase of the vertical depth,the soil pH value increased in turn,and the difference between the layers was larger.The soil thermal conductivity decreased from the top of the slope to the bottom of the slope,and the depth was higher,but it was less than the soil thermal conductivity of the soil without subsidence.In different depths,the soil thermal conductivity of the collapsed and the non subsided soils has a similar trend,and the soil thermal conductivity tends to increase first and then decrease with the depth of the section.The soil alkali hydrolysable nitrogen,soil available phosphorus and soil quick available potassium showed a trend of migration from the top of slope to the edge of water accumulation in the direction of slope,and the trend of enrichment in the subsidence center.The migration and change of soil alkali hydrolysable nitrogen and soil available phosphorus were relatively clear,and the change of soil available potassium migration was relatively higher.Small? In the whole subsidence area,soil alkali hydrolysable nitrogen,soil available P,soil available potassium content and soil organic carbon content have the same distribution pattern in soil profile,that is,with the increase of soil depth,the decline range is ranked as soil available phosphorus > soil alkali hydrolysable nitrogen > soil available potassium;0 ~ 40 cm soil layer breeding.The amount of available N,P and K in surface soil is higher than that in deep layer,and the content of available N,P and K in deep soil is relatively small.(3)The relationship between soil organic carbon and other soil physical and chemical properties in subsidence area is based on scientific evidenceThe comprehensive average value of spatial variation coefficient of soil organic carbon and soil basic physical properties on different slope positions is: soil thermal conductivity > soil organic carbon > soil water content > soil bulk density > soil pH;the comprehensive average value of spatial variation coefficient in different depths is different from the order of different slope position according to size,the largest of which is different.It is soil water content,followed by soil thermal conductivity and soil organic carbon,and the smallest is soil pH.On the whole,the effect of coal mining collapse on soil organic carbon is larger than other physical properties on different slopes,and soil organic carbon is less influenced by other physical properties than other physical properties.The spatial variation coefficient of soil organic carbon and soil available N,P and K on different slope positions was the same as that of soil available P > soil alkali hydrolysable nitrogen > soil organic carbon > soil available K,which was the same as that in different depths.On the whole,the soil available P and soil alkali hydrolysable nitrogen were greatly influenced by coal mining at different slope and different depths,and the content of nutrients fluctuated greatly.Compared with soil available phosphorus and soil alkaline nitrogen,the fluctuation of soil organic carbon and soil available potassium content was relatively small.The correlation analysis between soil organic carbon and other soil physical and chemical properties on different slope positions in the subsidence area: soil organic carbon and soil bulk density and soil water content have a negative correlation,and the soil moisture content reaches a significant level,the correlation coefficient is-0.63*(p<0.05),and the soil bulk density reaches a very significant level,the correlation coefficient is-0.492**(p<0.01);soil organic carbon has a positive correlation with soil alkali hydrolysable nitrogen,soil available phosphorus and soil available potassium,in which the soil available phosphorus and soil available potassium reached a significant level,the correlation coefficient was 0.476* and 0.427*(p<0.05),and the soil alkali hydrolysable nitrogen reached a very significant level,the correlation coefficient was 0.655**(p<0.01).Soil alkali hydrolysable nitrogen,soil water content,soil bulk density,soil available P and soil available K are closely related to soil organic carbon in the subsidence slope,and the soil alkaline nitrogen and soil organic carbon have a very significant positive correlation,and the relationship is most closely related.Correlation analysis between soil organic carbon and other soil physical and chemical properties in different depths of subsidence area: soil organic carbon and soil bulk density and soil water content have a negative correlation,and the soil moisture content reaches a significant level,the correlation coefficient is-0.384*(p<0.05),and the soil bulk density reaches a very significant level,the correlation coefficient is-0.643* *(p<0.01);soil organic carbon was positively correlated with soil alkali hydrolysable nitrogen,soil available phosphorus and available potassium,in which the soil alkali hydrolysable nitrogen reached a very significant level,the correlation coefficient was 0.878**(p<0.01),and the soil available P and available K did not reach a significant level.In different depths,soil alkali hydrolysable nitrogen,soil bulk density and soil water content are closely related to soil organic carbon distribution,and the highest correlation is soil alkali hydrolysable nitrogen,which is the same as that in different slope positions.In addition,the relationship between soil water content and nutrients is closely related,indicating that the migration and loss of water between different depths lead to nutrient migration and loss.Soil alkali hydrolysable nitrogen,soil bulk density and soil water content are important factors affecting soil organic carbon content and distribution in the subsidence area at different slopes and different depths,and the soil organic carbon and soil alkali nitrogen are strongly correlated.Soil moisture plays a very important role in the transportation and distribution of nutrient contents in the slope and vertical section. |
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