| Under the severe situation of increasing shortage of land resources,expanding the development and utilization of saline land and promoting the ecological utilization and industrialized development of saline land resources are important means to adhere to the "red line of 1.8 billion mu of cultivated land" and maintain the dynamic balance of the total amount of cultivated land.Many studies have been conducted on saline-alkali lands in the Yellow River Delta.Most of the heavy saline-alkali lands are aimed at ecological protection,focusing on regional environmental changes,dynamic characteristics,and prediction mechanisms.However,the light to moderate saline-alkali lands are premised on efficient utilization,and focus on the sustainable development of regional agriculture.However,the current research on soil quality changes in light to moderate saline-alkali lands is relatively lacking.In order to study and master the soil quality of light to moderate saline-alkali lands in the Yellow River Delta,this study takes the Agricultural High-tech Industry Demonstration Area of the Yellow River Delta as a typical representative region,and uses the grid distribution method to conduct field sampling surveys of regional soil in October 2021(corn maturity)and June 2022(wheat maturity).Using methods such as classical statistical analysis and spatial interpolation,exploring the changing rules of soil physical and chemical indicators and nutrient indicators in the Agricultural High-tech Industry Demonstration Area of the Yellow River Delta,and use the Minimum Data Set(MDS)to calculate the soil quality index in the Agricultural High-tech Industry Demonstration Area of the Yellow River Delta,at the same time,referring to national standards and previous studies to grade and compare the soil quality of each township in the study area,the main influencing factors of soil quality in the study area were determined by introducing an obstacle degree model in order to provide a scientific basis for the ecological and comprehensive utilization of saline-alkali lands in the area.The main findings are as follows:(1)Soils in the lower layer(20-40 cm)of the study area were more compact and alkaline than those in the upper layer(0-20 cm);soil nutrient contents(soil organic matter,total nitrogen,total phosphorus,ammoniacal nitrogen,nitrate nitrogen)in the upper layer were higher than those in the lower layer;soil salinity,cation exchange,total potassium,and available phosphorus were greatly affected by seasonal changes,and the changes in the upper and lower layers were not consistent between the two periods,with soil salinity content being most strongly affected by seasonal changes.The distance from the sea affects the spatial distribution of soil quality evaluation indexes.The high value areas of soil nutrient indexes and cation exchange are distributed in the central and western regions,and the high value areas of soil capacitance,soil p H and soil salinity are distributed in the eastern coastal region.Soil total nitrogen,total phosphorus,cation exchange and organic matter showed that cropland > forest land > wasteland;the total potassium content of forest land was higher than that of cropland and wasteland,the available phosphorus content of cropland was higher than that of forest land and wasteland,and the salt content of wasteland was significantly higher than that of cropland and forest land.Other indicators were not uniformly distributed among land use types in different periods.(2)According to national standards and combined with the actual situation of the study area,a total of 11 evaluation indicators were selected and a total of 5 indicators of total nitrogen,total potassium,available phosphorus,ammonia nitrogen and nitrate nitrogen were screened by principal component analysis to construct a minimum data set for the calculation of the comprehensive soil quality index.Different soil layers,land use patterns,and distance from the sea significantly affected soil quality in the study area.The overall performance of soil quality in the study area is cultivated land>forest land>wasteland.The soil quality in the 0～20 cm soil layer is significantly higher than that in the 20～40 cm soil layer.The soil quality index was significantly positive correlated with the distance from the sea.The Agricultural High-tech Industry Demonstration Area of the Yellow River Delta is mainly composed of middle and low grade land,that is classified by soil quality level,the average soil quality grade in the study area is 5.23,the higher(grade 1-3)land is mainly distributed in the south-central and west-central areas of the study area;moderate(grade 4-6)ground is scattered in the north,south,west and the transition area from the middle to the east of the study area;the low-grade(grade 7-10)land occupies almost half of the area of the study area,mainly distributed in the eastern part of the study area and the transition area from the middle to the east.According to the ranking of the average soil quality grade of the towns and townships in the Yellow River Delta Agricultural High-tech Zone,it can be seen that Huanghe Road Street,Dongcheng Street(grade 10),Guangrao Binhai New Area Management Committee(grade 8.72),Yangkou Town(grade 8.71),Liuhu Town(grade 6.61),Dongying Agricultural High-tech Industrial Demonstration Zone(grade5.49),Dadou Town(grade 4.38),Dingzhuang Town(grade 3.83),Daozhuang Town(grade 3.75),Chenguan Township(grade 2.42).The soil quality level of Huanghe Road Street,Dongcheng Street and Guangrao Binhai New Area Management Committee is poor,while the soil quality level of Chenguan Township and Daozhuang Town is high.(3)The main obstacle factors affecting the Agricultural High-tech Industry Demonstration Area of the Yellow River Delta are organic matter,total nitrogen and total phosphorus.In the future,we should combine the actual situation and requirements of light to medium saline land management in the region,steadily increase the application of organic fertilizer,optimize the planting structure,promote soil testing and fertilization techniques,and ensure irrigation and drainage,et al.We should not only focus on the productivity of the land,but also on the sustainable use of saline resources. |
