Study On Spatiotemporal Heterogeneity And Influencing Factors Of Soil Nutrients On Slopes In The Feldspathic Sandstone Region

The climate in the feldspathic sandstone region of the Yellow River Basin is dry,the terrain is cut and fragmented,and the vegetation is very sparse.Multiple dynamic types of erosion such as hydraulic,wind,and gravity interact and overlap.The amount of yellow mud and sand injected into the Yellow River every year in this area is up to 350 million tons,of which the amount of coarse sediment(particle size>0.05 mm)is about 2.8 tons.It is the concentrated source area of coarse sediment of the Yellow River.The serious water and soil loss in this area has caused the decline of soil fertility and the degradation of land productivity,affecting the local agricultural and animal husbandry production and the sustainable development of society.Studying the spatiotemporal distribution characteristics and influencing factors of soil nutrients on the slope scale in the arsenic sandstone area has important theoretical value for ecological restoration and rational utilization of soil and water resources in the area.This study selected typical slopes of small watersheds in the feldspathic sandstone region as the research object,and used methods such as classical statistics and geostatistics to study the spatiotemporal variation characteristics of soil nutrients(organic matter,total nitrogen,total phosphorus,total potassium,available phosphorus,available potassium,and hydrolyzable nitrogen)at the slope scale.The effects of factors such as microtopography,vegetation,and soil physical properties on soil nutrient indicators were analyzed and clarified.The main conclusions are as follows:(1)As the seasons change,the average content of soil SOM in winter is relatively highest,the average content of soil TN,TP,and TK is lowest in winter,and the average content of soil AP,AK,and AN is lowest in spring.The overall variation of soil nutrients with slope position shows a pattern of higher values on shady slopes than on sunny slopes,higher values on gullies than on slopes,and higher values on slopes and on slopes.(2)The spatial distribution patterns of soil nutrients at different soil depths can be fitted using spherical models,exponential models,and Gaussian models.There is a strong and moderate correlation between soil nutrients at different soil depths,with soil SOM,TK,and AN showing patchy mosaic distribution,while soil TN,TP,AP,and AK showing a strip-shaped distribution pattern.The overall soil fertility shows a trend of high in the northwest and low in the southeast.(3)There is a highly significant correlation between soil nutrients and slope position,slope variability,and elevation;There is a highly significant correlation between soil nutrients and vegetation community factors(excluding evenness);Most soil nutrients have extremely significant correlations with other soil physical property factors;Soil moisture content,vegetation coverage,vegetation biomass,and slope position are the dominant factors affecting soil nutrients.