Three-Dimensional Variation Characteristics Of Soil Salinity And Its Influencing Factors In Arable Land Of Yellow River Delta

With the rapid growth of population,the contradiction between man and land is becoming more and more serious.How to improve the quality of cultivated land and make rational use of cultivated land has become an important issue in today's society.Salt is one of the key factors affecting the quality of cultivated land.At present,the analysis of soil salt mostly stays in the two-dimensional stage,so it is impossible to diagnose the factors affecting cultivated land comprehensively.Therefore,it is very important to analyze the three-dimensional spatial distribution of salt and its influencing factors.The Yellow River Delta is an important grain production base in China,and has a large number of cultivated land reserve resources,which is seriously affected by salinization.Taking the coastal area of the Yellow River Delta as the research area,based on field in-situ sensing detection,indoor laboratory analysis and 3S technology,using the method of three-dimensional analysis and geographic detector,this paper explores the spatial differentiation characteristics and influencing factors of cultivated soil salinity in four scales of region,county,farm and field.The main research contents and results are as follows:(1)The interpretation models of soil salinity data of cultivated land with different scales are constructed.Using the correlation regression analysis method,the soil salt interpretation models based on in situ sensing detection conductivity in the field were constructed for Binhai district,Wudi county,farms and fields,with S_t=0.0021EC₀+0.7507?S_t=0.0021EC₀+0.764?S_t=0.0021EC₀+0.8139?S_t=0.0021EC₀+0.8487.The correlation coefficients were 0.873,0.882,0.927,and 0.945,all of which were greater than 0.85.It was possible to obtain soil salinity data based on the in situ conductivity interpretation in the field,and the accuracy of model interpretation increased gradually with the spatial scale from large to small.(2)The 2D spatial variation characteristics of salinity in different soil layers of cultivated land at different scales were analyzed.The salt content of all soil layers in the coastal area showed an obvious trend of gradually increasing from south to north,and then decreasing from west to east,and the overall trend of gradually increasing from southwest to northeast;the soil salt content of cultivated land in Wudi County showed a trend of gradually increasing from south to north and from west to east;the salt content of cultivated land in farms showed a characteristic of gradually increasing from southwest to northeast,with patches of high salt content in local sections.The soil salinity of typical fields showed a trend of decreasing and then increasing from northwest to southeast.From regional to farm scale,the spatial trend of soil salinity is basically the same,while specific fields show local specific characteristics.(3)The 3D spatial variability of soil salinity in arable land at different scales was analyzed.At different spatial scales,the soil salinity of arable land showed a"bottom aggregation"distribution in the vertical direction in general and a significant"surface aggregation"feature in the local area.As the spatial scale decreases,the variability tends to be simpler from complex to simple,and the degree of variability of soil salinity gradually decreases.The salinity of the arable land in the coastal area as a whole shows"bottom aggregation"distribution characteristics,while the northern part of the region,especially the northern offshore zone in the middle section,shows obvious"surface aggregation"distribution characteristics,while the salinity of the arable land in the southern part of the region is lower with"surface aggregation"characteristics."In the northern part of the region,especially in the central part,the northern offshore zone shows obvious"surface aggregation"distribution characteristics.In the northwestern part of the farmland in Wudi County,there is a small range of"aggregation type at both ends"characteristics,and the overall performance is significant"bottom aggregation type"distribution characteristics.The southern part of the farmland has obvious"bottom aggregation"distribution characteristics,and the northern part has"two-end aggregation"distribution characteristics.The typical field as a whole exhibited obvious"bottom aggregation"characteristics,while the light and heavy soil salinity trends were not completely consistent with other scale distribution characteristics.(4)The factors influencing the spatial variability of salinity in arable soils at different scales were analyzed.Based on Geo Detector to analyze the factors influencing the spatial variability of soil salinity in arable land at different scales,the results of factor detection showed that there were some differences in the explanatory power of factors influencing the spatial distribution of soil salinity in different soil layers at different scales and their interactions.The maximum q-value of the factors affecting the spatial distribution of soil salinity in farmland in the coastal area is soil moisture(0.2069),the maximum q-value of natural factors is elevation(0.0935),and in Wudi County,respectively,is planting crops(0.1322)and soil texture(0.2400),and the pattern of spatial distribution of soil salinity is gradually and significantly affected by natural factors as the depth of soil layer increases.The most influential factor affecting the spatial distribution of soil salinity on farms was texture(0.0642),and p H(0.1424)in typical fields.Compared with the explanatory power of a single factor,the explanatory power after the interaction of any two influencing factors was higher than the explanatory power of each factor,and all of them showed non-linear enhancement or two-factor enhancement,without weakening or independent features.There were significant differences in the influence of p H?planting type,soil moisture?p H,and organic matter on the spatial distribution of soil salinity in coastal areas,and p H?texture on the spatial distribution of soil salinity in Wudi County,and there were no significant differences between the interaction factors of farms and typical fields.