Spatio-temporal Evolution And Driving Force Analysis Of Cultivated Land Quality In The Yellow River Delta

Cultivated land is one of the most important means of production in agricultural production.Good cultivated land quality is an important foundation for ensuring national food security and social stability.Protecting cultivated land is a basic national policy in China.Therefore,understanding the changes in cultivated land quality and their driving forces is an objective demand for sustainable utilization of cultivated land resources and agricultural development.The Yellow River Delta is a newly silted land formed in modern times.Groundwater is shallowly buried and highly mineralized,soil salinization is severe,land use structures are complex,and the ecological environment is fragile.Timely understanding of changes in the quality of cultivated land in this area and their causes is of great significance for the sustainable development of regional agriculture,economy,and society.This study selected the ecologically fragile area of the Yellow River Delta,and used the survey and analysis data from 2007 and 2015 to construct a cultivated land quality evaluation index system composed of eight factors.It conducted a quantitative evaluation of the cultivated land quality in the two temporal phases of the study area,and then analyzed the temporal and spatial dynamics of the cultivated land quality.On this basis,11 influencing factors were selected,and the main driving forces that affected the changes in cultivated land quality in the study area were analyzed using principal component analysis.Based on the evaluation indicators of cultivated land quality,obstacle analysis was conducted,and cultivated land quality protection and utilization zones were divided,and targeted countermeasures and suggestions for protecting and improving cultivated land quality were proposed.The main research contents and results are as follows:(1)According to the actual situation of the study area,eight factors were selected as the evaluation factors,including irrigation and drainage conditions,geomorphic types,salinization degree,tilth texture,soil structure,organic matter,available phosphorus,and available potassium.The evaluation index system for cultivated land quality in the Yellow River Delta was constructed.The index weight was determined by using the analytic hierarchy process,and a membership function model was constructed.The comprehensive index method was used to quantitatively evaluate the quality of cultivated land in the study area in 2007 and 2015.(2)In 2007 and 2015,the average grade of cultivated land quality in the study area was4.09 and 4.75,respectively.The overall quality of cultivated land was mainly medium,with high grade land of 75115.81 hm~2and 64400.24 hm~2,accounting for 39.10%and 29.21%of the total area,respectively.It was mainly distributed in the southern inland and central coastal areas of the Yellow River.The medium grade land had an area of 97833.58 hm~2and109643.48 hm~2,accounting for 50.92%and 49.73%,respectively,and was widely distributed in the central and northern regions,The cultivated area of low-grade land is 19167.11 hm~2and46453.30 hm~2,accounting for 9.98%and 21.07%respectively,and is scattered in the central region of the study area.From 2007 to 2015,the quality of cultivated land in the study area showed an overall downward trend,with a decrease in the proportion of high-grade cultivated land,an increase in the proportion of medium and low-level cultivated land,and a significant difference in the quality of cultivated land between districts and counties.The quality of Dongying District decreased most significantly,while Lijin County showed a slight increase.The quality of different types of cultivated land use decreased most in paddy fields,followed by dry land and irrigated land,The declining areas of cultivated land quality are mainly concentrated in the central and northeastern coastal areas of the study area,while the areas with increased and unchanged quality are mainly distributed in the southern and northern areas along the Yellow River in the study area.(3)The main driving factors for changes in cultivated land quality in the study area are economic development,population growth,and agricultural technology.According to principal component analysis,the most significant factors affecting the quality of cultivated land are GDP per capita,the proportion of agricultural output value,and the intensity of land development and utilization;Total population growth rate and proportion of agricultural population;Average agricultural machinery power,fertilizer application intensity,and effective irrigation area ratio.(4)The diagnosis results of obstacle factors indicate that the main obstacle factors to the quality of cultivated land in the study area are irrigation and drainage capacity,organic matter,and salinization degree.According to the diagnosis results of obstacle factors and combined with the combination of obstacle factors,the cultivated land in the study area is divided into comprehensive protection areas for cultivated land quality,comprehensive improvement areas for cultivated land quality,improvement areas for irrigation and drainage capacity of cultivated land,improvement areas for soil salinization of cultivated land,and improvement areas for soil organic matter of cultivated land.Suggestions for protecting and improving the quality of cultivated land are proposed based on the differences between the protection and utilization areas of cultivated land.This study has better understood the spatiotemporal variation characteristics and main driving factors of cultivated land quality in the Yellow River Delta,and has positive significance for the protection,sustainable utilization,and management of cultivated land resources in the region.