Temporal And Spatial Differentiation Characteristics Of Organic Matter In The Plow Layer In The Cross Zone Of Mountain And Hills In Western Hubei Province

In the context of the new era,in order to ensure national food security and provide an important foundation for the realization of the national rural revitalization strategy,the protection and improvement of cultivated land quality is particularly important.Soil organic matter(SOM)in the cultivated layer,as an important nutrient and an important component of soil structure in cultivated land,is of great significance for promoting the improvement of cultivated land quality.In this study,Xiangfeng Town,Laifeng County,Hubei Province,which is a typical landform in the cross zone of mountains and hills in western Hubei Province,was used as the research area.The spatial and temporal distribution characteristics of SOM and its influencing factors are discussed.The collection,data and collection time of soil samples were 1 year in the 1980s(hereinafter referred to as the 1980s)and 3 years in the 2010s(hereinafter referred to as the 2010s).Among them,the data of 20 soil samples in the 1980s were collected and sorted out according to the data of the second national soil census.In the 2010s,the number of sample points in 2008,2015,and 2019 were 698,377,and 302,respectively,for a total of 1,377 sample points.The statistical and geostatistical methods used in this study mainly include K-S test,kurtosis and skewness test,independent sample T test,paired sample T test,rank sum test,optimal scale regression analysis,spatial correlation analysis,variance Statistical and geostatistical methods such as function analysis,simple kriging,and inverse distance weighting.Through the above steps,the main conclusions of this study are as follows:(1)On the spatial scale,the SOM content in the study area in 2008 ranged from 12.69g/kg to 38.69g/kg,with an average value of 25.69g/kg.The high SOM content was mainly distributed in the northwest,southwest and southeast of the study area.The low value is mainly distributed in the east and south.In 2015,the SOM content ranged from 16.98g/kg to 28.14g/kg,with an average value of 21.69g/kg.The high SOM content was mainly distributed in the southwest and north,and the low value was mainly distributed in the south and east.In 2019,the SOM content ranged from 16.30g/kg to 25.54g/kg,with an average value of 20.80g/kg.The high SOM content was mainly distributed in the middle,and the low SOM content was mainly distributed in the south and north.(2)On the time scale,the variation characteristics of the study area(change in organic matter)are different and change with time.On the short-term scale,in the 10s,from 2008 to 2019,the study area as a whole continued to decline,with an average annual change of-0.44g/kg;among them,the decline rate was faster from 2008 to 2015,with a change of-16.95g/kg～9.07g/kg,the average annual change range is-0.57g/kg;from 2015 to 2019,the change range is-7.70g/kg～6.67g/kg,the average annual change range is-0.22g/kg,a decrease Slow down.On the long-term scale,from the 1980s to the 1910s,the overall SOM content in the study area increased,with a range of15.93g/kg～20.25g/kg,and an average annual change range of 0.24g/kg.On a long-term scale,the study area rose,and on a short-term scale,the study area declined.(3)From the perspective of the classification of influencing factors,eight influencing factors of SOM in the study area were determined according to the optimal scale regression analysis:soil parent material,soil subtype,altitude(ASL),slope,typical planting system,pH,Available phosphorus(AP)and available potassium(AK)are divided into 4 categories.Among them,soil types include soil parent material and soil subtypes,topographic factors include ASL and slope,land use methods include typical planting systems,and other soil nutrient elements include pH,AP,and AK.(4)From the point of view of change characteristics,the decrease range(hereinafter collectively referred to as the decrease range)and the increase range(hereinafter collectively referred to as the increase range)under different influence factors in the study area have different degrees of significance,and different types or grades under the same influence factor changes in diferent characteristics.On the whole,quantitative factors such as ASL,pH,AP,AK,and slope are extremely significant at high levels,but when they decrease,the significance will also decrease,and when they reach extremely low values,the significance will be more significant or not significant.The composition of qualitative factors is complex,the characteristics of different types under different influencing factors are complex,and the overall significance is high.Taking the typical planting system as an example,in the plough layer of different typical crop planting systems,the SOM content of rice was the highest in 2008 and 2015,but it has been in a state of decline and has the largest decline,which is extremely significant,and vegetables have a larger decline,which is extremely significant.,the decrease of sweet potato is average,the significance is not high,it is more significant,the decline of corn is smaller,it is significant,the increase of orchard is more obvious,and the increase is extremely significant.