| Food security is related to national economic security.The black soil area in northeastern China has fertile soil and a vast area.It is an important commodity grain base in my country and is known as the"stabilizer"of my country’s grain production and supply.In recent years,the irrational use of arable land by humans has caused the black soil layer of sloping arable land to become thinner year by year,serious soil erosion,and reduced productivity of arable land,agricultural productivity is difficult to continue to increase.The role of black soil area as the"ballast stone"of China’s grain is at risk of shaking.The report of the 19th National Congress of the Communist Party of China proposed to speed up the“systematic management of landscapes,forests,fields,lakes and grasses”.In addition,in 2021,the 14th Five-Year Plan proposes to build1.075 billion acres of concentrated contiguous high-standard farmland.These requirements have brought up new issues in the quantity,quality and ecological safety of sloping farmland in Northeast China.Therefore,it has important theoretical and practical significance to increase the actual productivity of sloping farmland in the black soil area,ensure efficient land use and ecological protection.In order to improve the quality of cultivated land in black soil and maintain the sustainable use of cultivated land,this paper proposes a new contour planting model based on the cultivation practice of sloping cultivated land in the black soil area.This model can reduce regional soil erosion,improve land productivity,and provide reference for the development of high-standard farmland construction and the realization of the dual goals of ensuring food production and ecological security.In order to construct the contour planting model of sloping land in the black soil area,and analyze the actual productivity difference and the cause of the difference between contour planting and traditional ridge planting.We selected plots with significant spatial differences in crop growth over the years as the study area,which is located at Youyi Farm in Youyi County,Shuangyashan City,Heilongjiang Province.Based on the theory of landscape ecology and the management concept of landscape,forest,field,lake and grass system,construct a planting pattern with contour height on slope farmland in black soil area..And acquired remote sensing image data during the crop growth period from 2017 to 2020,and collected field topography,soil,crop growth,and yield data.Then we constructed a maize yield inversion model based on random forest,analyzed the differences in soil water content,crop growth and yield spatial patterns under different tillage measures,and explored the causes of the differences.The results of the study are as follows:(1)From the comprehensive perspective of"landscapes,forests,fields,lakes and grasses",we have constructed a new model of contour planting on sloping arable land in the black soil area,which is summarized as"contour ridge cultivation+ditches into canals+field division+partition measures".This model can cause changes in runoff by changing the micro-topography morphology of the surface.The optimal ridge degree of contour tillage is about 1°.At this time,the soil water and fertilizer loss of the cultivated land is small,and it has a certain drainage capacity.At this time,the crops in the field are growing better and the degree of spatial variability is significantly reduced.(2)A corn yield model that introduces topographical factors and multi-source image data for each growth period of the crop can improve the accuracy and stability of the inversion.Using terrain factors(elevation,aspect,solar radiation)and vegetation index extracted from multi-temporal remote sensing images to generate 14 data sets as input,combined with random forest model and leave-one-out cross validation method,the corn yield estimation models were constructed respectively.The study found that the addition of multiple growth period data and terrain factors can improve the accuracy and stability of the model to varying degrees.The combination of data sets of S1+S2+S3+terrain can obtain the best estimation result,R~2reaches0.796,and RMSE is 551.28kg/km~2.The model can not only reflect the vegetation information of different growth periods,but also integrate the influence of topographical factors on yield distribution.The model can accurately invert the spatial distribution of corn yield.(3)Contour ridge cultivation can optimize the internal water and soil configuration of the field,and the utilization efficiency of cultivated land has been improved significantly.By comparing the temporal and spatial distribution of soil water content,crop growth,and yield between the Denggao plot and the Duizhao plot,we found that contour cultivation can increase the water retention capacity of the field,balance the internal water and fertilizer conditions,the crop growth is more uniform,and the plots are average.Compared with the Duizhao plot,the Denggao plot’yield has increased by 9.16%.(4)In response to the research results,this study proposes countermeasures to increase the productivity of sloping farmland in the black soil area of Northeast China:the leading role of the government and cooperatives should be implemented,and the construction of high-standard basic farmland based on the contour planting model should be promoted on a large scale in dryland areas.Actively explore optimized management measures based on the contour planting model.Promote the implementation of land remediation projects according to local conditions,promote the coordinated operation of various farming measures and supporting agricultural machinery,and promote the integration of efficient use of cultivated land,land remediation,and ecological protection.This research can provide certain theoretical guidance for the promotion and implementation of contour planting in black soil areas,and provide ideas for completing the high-standard basic farmland construction tasks during the 14th Five-Year Plan,and provide theoretical and technical support for the country to achieve grain production,cultivated land protection,and ecological integration.It has important guiding significance for optimizing the integration of arable land resources in the black soil area,promoting the efficient use of arable land and ecological security,scientifically advancing the development of agricultural modernization,and maintaining the sustainable utilization of black soil. |
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