Study On The Spatial Variability Of Soil Organic Matter And Influencing Factors In Transitional Zone

Soil organic matter has spatial autocorrelation and heterogeneity,and it is influenced by climate,topography and parent material and so on.It has great significance to explore the influence mechanism of influencing factors on soil organic matter.The plain hilly transition zone is a special terrain,and the distribution of soil organic matter in this area has its special rule and the influencing factors are morecomplicated.It is important to study the soil organic matter change in the transition zone to the soil carbon reserve and the global carbon cycle.Spatial regression model is an important tool for soil organic matter prediction and quantitative information management.In order to improve the prediction accuracy of soil organic matter in the transition zone to explore the spatial nonstationarity of the soil organic matter influenceing factors,and to further guide the field agricultural production,this article was based on the soil landscape quantitative model,and the geostatistical model was used as a tool.Linear regression model was used to predict the soil organic matter in the hilly area of the plain.The spatial variability of soil organic matter and the spatial nonstationarity of the influencing factors were analyzed.The soil organic matter was also studied by dividing the topography and landform The forecast provided a methodological reference and got the following conclusions:(1)Through the correlation analysis and stepwise linear regression,the best explanatory variables of the model were chosen: elevation,slope,aspect,effective iron,soil bulk density,soil gravel,clay.GWRK.considered the spatial heterogeneity and local nonstationarity of soil organic matter and influencing factors,and a more suitable influencing factors were chosen as the auxiliary variable.GWRK also choose different bandwidth for different environment variables,which has a better predictive effect than OK and RK.(2)GWR model can calculate the weight of influencing factors,and then the influence coefficient distribution map can be drawn,from which the degree of influence factors on soil organic matter content can be obtained.The influence degree of elevation on the northeast the weakest and the transition area is the region with the highest degree of influence.The area where the aspect towards the solar radiation is more conducive to the accumulation of SOM.The western and eastern regions have the greatest effect on the slope,and gradually decreased from both sides to the middle.The effect of clay on the SOM was significant.The influence of soil density and soil gravel was similar and the trend is opposite.The effect of clay on SOM is remarkable,and the influence of the northwest to southeast gradually decreases.The highest value area is located in the central and western regions,and the lowest value area is located in the southeast.This law can be targeted for agricultural reform measures,according to local conditions to provide reference for agricultural production.(3)Choosing the terrain elevation degree and elevation as the comprehensive division criterion,by calculating the terrain relief degree under the multi-scale calculation window.The change law of neighborhood area and terrain undulation is analyzed,and the inflection point of the increase of topographic fluctuation is regarded as the best statistical unit.Using the significant difference model of elevation difference,the best statistical unit is obtained.Taking the elevation 200 m as one of the criteria,the terrain elevation degree standard test is carried out,and the terrain is divided into plain area,hilly area and transition zone.The results show that the prediction accuracy of the plain area is higher than that of the whole region,and the accuracy of the mean error,the root mean square error,the inaccuracy and the correlation coefficient are the same as those of the sub-region after the terrain division.The prediction accuracy of the transition zone is slightly improved and the improvement rate is smaller than that of the plain area.The accuracy of the hilly area is slightly lower than that of the whole area.