Research On Quality Evaluation Of Paddy Land In Agricultural And Reclamation Areas Based On Remote Sensing

The survival and development of human beings cannot do without the basic resource of cultivated land,the quantity and quality of cultivated land determines the food security of a country.As one of our important grain production bases,the northeast black soil area has advantages such as high soil fertility and good quality of agricultural products,which is of great significance to ensuring national food security.Heilongjiang province is an important rice production base in our country.The paddy field area accounts for about 28% of the total cultivated land in the province.Its rice yield is high,the quality is good.With the continuous development of cultivated land resources,problems such as soil erosion,water and soil loss and thinning of surface layer become prominent,threatening the utilization of cultivated land resources.The quality of paddy land is also different between reclamation area and agricultural area because of the development years,infrastructure and land size.To sum up,it is of great significance to monitor and evaluate the quality of paddy land in agricultural areas and reclamation areas,and put forward targeted suggestions based on the evaluation results for improving the quality of paddy land and ensuring food security.This study takes Friendship Farm in reclamation area and Jinshan Town,Chang ’an Town and Toulin Town in Fujin City as the research area.The paddy field quality evaluation index system of paddy field was constructed from five aspects: tillage conditions,soil property,soil nutrient status,irrigation and drainage capacity,and cultivated land productivity.The corresponding spatial data of cultivated land quality evaluation index were obtained based on remote sensing and GIS technology,the weight of evaluation index was determined by AHP combined with Delphi method,and the nonlinear membership function was used to quantify the evaluation index.The cultivated land quality evaluation model of paddy field was established,and the pixel was used as the evaluation unit to comprehensively evaluate the paddy field quality in the study area,and the evaluation results were obtained.On this basis,the quantitative distribution and spatial distribution characteristics of paddy field quality in agricultural and reclamation areas were analyzed,and reasonable suggestions were put forward to improve paddy field quality.The main research results are as follows:(1)The index obtained by remote sensing can be used to evaluate the quality of paddy land in agricultural and reclamation areas.The variation standard of NDVI can reflect the quality stability of paddy field.The smaller the standard deviation of NDVI variation,the more stable the cultivated land quality.The RF algorithm used in SOM inversion with image band and spectral index as input has higher accuracy and can better characterize the spatial distribution of organic matter.(2)The quality of paddy field in reclamation area is generally better than that in agricultural area.The average score of paddy field quality of Youyi Farm in reclamation area was 0.8614,and that of Fujin Three towns in agricultural area was 0.8210.The main reason for the quality difference was the difference of irrigation and drainage capacity.The irrigation and drainage capacity of farm is better than that of agricultural area.(3)The proportion of medium and low quality paddy field in agricultural area is significantly higher than that in reclamation area.The paddy field in the study area was divided into five grades.In Friendship Farm,the second grade accounted for 64.47% of the paddy field area,and the first three grades accounted for 98.12%,the proportion of paddy fields with slightly poor quality is less.In Fujin three towns,the proportion of third-grade water is the largest,which is 47.14%,and that of the first three grades is 78.94%.Compared with Friendship Farm,the proportion of high quality arable land is less,and the proportion of low and medium quality paddy land is more.(4)The low grade paddy field in agricultural area and reclamation area has obvious spatial agglomeration.The spatial Gini coefficient was used to calculate the spatial aggregation degree of paddy field mass.The fifth and fourth grade paddy fields in agricultural and reclamation areas have certain agglomeration in spatial distribution.The spatial agglomeration of paddy fields of grade 1 and Grade 2 and Grade 3 with large area distribution was not obvious.(5)Agricultural area and reclamation area adopt different measures to improve paddy field quality.The main limiting factors of paddy field quality were available P,organic matter,surface layer thickness and drainage capacity in reclamation area,while those in agricultural area were available P,organic matter,drainage capacity,surface layer thickness,irrigation capacity and plot shape index.According to the evaluation results,from the perspective of paddy field quality improvement and agricultural modernization development,In order to carry out the land fertility improvement project,improve the field supporting facilities,strengthen the government guidance,social participation and other aspects for the agricultural area and reclamation area respectively put forward reasonable suggestions.