Study On Remote Sensing Evaluation Of Cultivated Land Quality From The Perspective Of Land Consolidation

Cultivated land is an extremely important natural resource,and the quality of cultivated land is closely related to crop productivity.The quality of cultivated land directly affects the national food security and the development of agricultural industry.Land consolidation is an important way to rationally utilize land resources and a key means to promote the construction of high-standard farmland.However,the current evaluation of land consolidation focuses on economic benefits and performance evaluation,and we do not pay enough attention to the evaluation of cultivated land quality before and after land consolidation,which is not conducive to the protection of cultivated land resources and the promotion of modern agriculture.The traditional cultivated land quality evaluation method relies on the field sampling results,and the overall situation is represented by the sampling point data,which has the characteristics of strong subjectivity,long investigation period and high cost.Therefore,it is of great significance to give full play to the advantages of GIS and remote sensing technology to realize the evaluation of arable geology from the perspective of land consolidation.This study takes the paddy field and grid transformation project area of Hongwei Farm as the research area,uses UAV RTK image data to complete cultivated land utilization interpretation and DSM extraction,uses GF-2 high spatial resolution imagery to calculate NDVI,and converts sampling point data into spatial data.At the scale of paddy fields and ponds,a remote sensing evaluation system for cultivated land quality based on the perspective of land consolidation is established from three aspects: engineering quality,spatial quality,and soil quality.In this paper,the threshold value method is used to quantify the indicators,and the weight of the indicators is determined by combining the analytic hierarchy process and the expert scoring method.At the same time,the changes in the quantity and spatial distribution of cultivated land of different grades before and after paddy field improvement in the study area were analyzed,and the driving factors of cultivated land quality changes were discussed in combination with the crop growth in 2019,2020,and 2021.The result is as follows:(1)The average score of cultivated land quality before land remediation was 81.04,and the average score after the implementation of the remediation project was 84.08,an increase of 3.04 points.The average score of engineering quality increased by 22.13 points,the average score of space quality increased by 53.29 points,and the average score of soil quality decreased by 11.86 points.(2)The quality of cultivated land is divided into five grades according to the equidistant method.Before the implementation of the land consolidation project,the third and fourth grades accounted for 70%,and the quality of cultivated land was average.After the implementation of the land remediation project,all the pond blocks are in the top three grades,and the quality of the cultivated land is good.In terms of spatial distribution,the areas with higher quality of cultivated land before and after land consolidation are concentrated in the southeast corner,where the terrain is lower.Before land consolidation,the quality of cultivated land in the northwest region was relatively low,and the overall distribution of cultivated land quality was similar to the terrain,with a gradient trend.After land consolidation,the original trend is not obvious,and the areas with low quality of cultivated land are mainly concentrated in the west side of the central part of the cultivated land.(3)Crop growth is a comprehensive representation of the quality of cultivated land,and the heterogeneity of growth can reflect the uniformity of crop growth in the grid and within the field,thereby further reflecting the internal homogeneity of cultivated land quality in the evaluation unit of cultivated land quality.Through the comparative analysis of inter-annual growth heterogeneity,the impact of engineering factors on the quality of cultivated land can be reflected.(4)Crop growth is greatly affected by soil fertility.Before and after land consolidation,crop growth and key soil indicators SOM,TP,and AN were extremely significantly correlated at the level of 0.01,and the correlation coefficient was around 0.75.However,after the implementation of the remediation project,due to the soil disturbance during the construction and the improper management and operation of the large grid field,the correlation coefficients have both decreased,and the decrease rate is about 0.05.(5)Topography affects soil nutrient distribution,with a correlation coefficient of around 0.65,and also affects crop growth,which is statistically significant except for 2020.Land consolidation can weaken the influence of topography on nutrient distribution,but the process of topsoil stripping,transportation,and resurfacing during construction will damage the soil physical structure to a certain extent,which will reduce soil nutrients and increase the spatial variation coefficient.It takes a certain restoration period to restore.The quality of cultivated land has become an important factor affecting the decline of soil quality.(6)From the perspective of land consolidation,compared with conventional evaluation methods,cultivated land quality evaluation based on field scale can highlight land use patterns,changes and differences within fields.The evaluation results can provide a theoretical basis for the development of fine agriculture,and provide suggestions for the optimization and maintenance of land consolidation.