Effects Of Climate,Topography And Soil Properties On Soil Available Potassium Across China

Soil available potassium(AK)is the main soil potassium(K)pool to plant.Thus,quantitatively assessing the content and distribution of AK in soil,and charactering its influence factors is an important step toward reasonable assignment of potash fertiliser.In this paper,we choose the farmland in the east(Heilongjiang-Guangdong)and north(Xinjiang-Liaoning)of China as the research areas to study the content of soil readily available potassium(RAK)and slowly available potassium(SAK).Through the combination of experiments in a laboratory and ArcGIS software platform,we use the geostatistical method to explore the spatial distribution characteristics of soil RAK and SAK content in different climatic zones and vertical zones in China and obtain the K fertility in farmland soils in eastern and northern China.SPSS software was used to conduct descriptive statistical analysis on climate,topography and soil properties.Stepwise regression analysis were used to study the relationship between climate,topography,soil properties and soil AK,and the dominant factors affecting soil RAK and SAK and the effect mechanism were obtained.The main results are as follows:(1)With the increase of latitude in the south-north belt,the mean annual temperature gradually decreases,and the change of mean annual precipitation is relatively weak.In the east-west belt,the mean annual temperature changes weakly with increasing longitude,and the mean annual precipitation changes gently firstly and then gradually increases.In the south-north belt,the topographic factors are highly variable except for slopes.In the east-west belt,the elevation decreases with the increase of longitude.In the study area,the soil particle composition and pH are highly heterogeneous.(2)The results of geostatistical analysis show that the distributions of soil RAK and SAK show a massive distribution,and the contents of RAK and SAK in soil are higher in the east-west belt and lower in the south.According to the ArcGIS software classification area statistics,the RAK content in the soil is relatively abundant,the proportion of the high grade is 38.47%.The soil SAK content is moderate,and the proportion of the moderate grade is 38.68%.(3)The values of soil RAK and SAK are highest in the middle temperate arid areas,which are 186.19 mg/kg and 906.59 mg/kg,respectively.In general,the contents of soil RAK and SAK are higher in the areas with lower temperature and humidity.In vertical gradient zones,the contents of soil RAK and SAK increase firstly,and then decrease when the altitudes are higher than IV.The contents of soil RAK and SAK are highest at the level of IV(500-1000 m),and the contents are 181.21 mg/kg and 935.32 mg/kg,respectively.(4)Climatic factors show extremely significant correlation with soil RAK and SAK.In the topographic factors,both elevation and slope are significantly correlated with soil RAK and SAK,while the correlation between other topographic factors and soil K is not significant.Among the soil properties,pH and BS show extremely significant correlation with soil AK,while the correlation between other soil properties and soil K is not significant.There is a significant correlation between clay,pH and BS and SAK in soil.There are significant correlations between grit and CEC and SAK in soil,while the correlations between other soil properties and SAK in soil are not significant.(5)In the study area,the climate is the main factor affecting the changes of soil RAK and SAK.In a single climate zone,topography and soil properties are important factors affecting soil RAK and SAK.