Soil Quality Evaluation And Obstacle Factor Analysis Of Different Land Use Types In Loess Plateau

The problem of soil erosion is very serious in the Loess Plateau,and the fragility of the ecological environment restricts the sustainable development of the region.Vegetation restoration is an effective measure to improve soil erosion and other issues,and the differences in vegetation types during the process have changed the land use type of the Loess Plateau,affecting its soil quality.Based on this,exploring the soil quality of different land use types in the Loess Plateau region is of great significance for the restoration and construction of the ecological environment and human production and life in the region.Therefore,this study focuses on soils of different land use types on the Loess Plateau,and establishes a soil quality evaluation system for different land use types on the Loess Plateau.That is,to construct a minimum dataset and combine it with a non-linear scoring function and the weighted additive soil quality index method to evaluate its soil quality.Finally,based on the diagnostic model of soil quality obstacle factors,the main obstacle factors that constrain soil quality of different land use types in the region were analyzed,and targeted strategies and suggestions were proposed to improve soil quality,providing scientific reference basis for soil quality evaluation in the Loess Plateau region.The main results were as follows:(1)In the Loess Plateau region,there were significant differences in soil physical,chemical,and biological indicators among different land use types.The soil water content(SWC)in natural grasslands and economic forests is significantly higher than other land use types,while the SWC in abandoned land was significantly lower than other land use types.The soil bulk density(SBD)in abandoned land and farmland was significantly higher than that in grassland and ecological forest,and there is a minimum value in artificial grassland.Soil organic matter(SOM)and soil available nitrogen(SAN)were higher in natural grasslands and ecological forests than in farmland and artificial grasslands than in economic forests and abandoned land.The soil total nitrogen(STN)showed the following order:natural grassland(1.54)>farmland(1.31)>ecological forest(1.16)>artificial grassland(1.00)>economic forest(0.96)>abandoned land(0.69).The soil total phosphorus(STP)of farmland was significantly higher than that of other land use types(p<0.05),and the soil available phosphorus(SAP)was significantly higher than that of ecological forests and artificial grasslands,and there was no significant difference compared to other land use types.The content of soil available k(SAK)in natural grassland was significantly higher than that in forests land,abandoned land,and artificial grassland,and there was no significant difference compared to farmland.The variation pattern of soil microbial biomass(MBC,MBN)in different land use types is consistent,in the order of natural grassland>ecological forest>artificial grassland>economic forest>farmland>abandoned land.The changes in soil enzymes except for soil catalase(SCAT)were consistent,with grassland being higher than other land use types.Soil catalase(SCAT)was higher in grasslands,farmland,and ecological forests,but lower in abandoned and economic forests.(2)In the Loess Plateau region,different minimum dataset construction methods were used to compare and determine the suitable minimum dataset selection method for soil quality evaluation system in the region.The results showed that the fitting effect between the soil quality index calculated from the minimum dataset 1(MDS1)and the total dataset(TDS)was better than other methods(R~2=0.8548),indicating that the MDS1 selection method can better replace TDS in evaluating soil quality of different land use types in the Loess Plateau region.Meanwhile,the selection of soil quality evaluation indicators in the minimum dataset will vary depending on the type of land use.The results were natural grassland(SQI=0.639)>artificial grassland(SQI=0.540)>ecological forest(SQI=0.448)>farmland(SQI=0.431)>abandoned land(SQI=0.382)>economic forest(SQI=0.317).Among them,the soil quality index of natural grassland was at a high level,the soil quality index of artificial grassland,ecological forest and farmland was at a medium level,and the soil quality index of abandoned and economic forest was at a low level.The results showed that economic forest could reduce soil quality,while ecological forest,grassland and farmland could improve soil quality.(3)The main obstacles to soil quality vary among different land use types,and the main obstacles to soil quality were mainly related to soil phosphorus and soil enzymes,especially soil enzymes.This indicates that soil enzymes may be the main obstacle factor restricting soil quality of different land use types in the Loess Plateau region.Among them,STN and alkaline phosphatase(SAPH)had significant barriers to soil quality in farmland.The obstacles of SAPH and SAP in ecological forest soil quality were significant.The obstacle degree of SAPH in artificial grassland soil quality was relatively high.The obstacle degree of SCAT in natural grassland soil quality was relatively high.SAP and SCAT had significant obstacles in abandoned soil quality,and SAP belongs to the category of severe obstacle factors.The obstacles of soil sucrase(SSC)in soil quality of economic forests were significant.(4)Protect natural grassland by combining natural force with human management.Fertilizer and organic fertilizer should be used together in farmland.It was suggested to give priority to the dominant native species suitable for local soil and climate conditions,and to plant mixed forest,the best later can use the natural force to restore the ecological forest.Economic forest suggested to reduce weeding frequency.Artificial grassland can increase the variety of herbaceous plants and improve the fertility of the land through mixed sowing technology.