| Northeast China is the "ballast rock" and "stabilizer" of China’s grain production.As one of the world’s four black soil regions and the famous "corn golden belt",northeast Black land is of great importance to maintain national food security.However,in recent years,due to the reuse of light cultivation,there are problems such as excessive application of chemical fertilizers and pesticides in the northeast black land,causing serious soil erosion and non-point source pollution,endangering the land ecological security,and food security risks.As a targeted management measure,precision management of cultivated land can implement cultivated land management according to local conditions,improve the efficiency of cultivated land use,reduce capital input,and maximize the benefit of cultivated land.It is an effective means of black land protection.Precision management zoning technology is the primary and basic part of the precision management of cultivated land.It can distinguish the heterogeneity of cultivated land and divide cultivated land in the same state into the same unit,serving for all kinds of precision management measures of cultivated land.The application of remote sensing technology in the field of accurate management and zoning has also greatly improved the efficiency and scientific nature of farmland management."National High Standard Farmland Construction Plan(2021-2030)" pointed out that the use of remote sensing technology,strengthen agricultural information construction,promote digital farmland construction;The Outline of northeast Black Land Protection Plan(2017-2030)also proposed to speed up the implementation of the strategy of "storing grain in land and storing grain in technology" with the help of modern technology.Therefore,the precision management zoning of cultivated land based on remote sensing is in line with the requirements of cultivated land management in the new era.In order to explore the influencing factors of precise management zoning of cultivated land and find a better input of zoning,this paper selected the typical cultivated land planted with corn in Friendship Farm to carry out the study of precise management zoning.Five Sentinel-2a satellite remote sensing images of the early stage of crop growth in the study area for five consecutive years from 2017 to 2021 were obtained,with A spatial resolution of 10 m after re-sampling.The normalized vegetation index(NDVI)was extracted to divide the precision management area.In addition,different terrain factors were introduced to form six different inputs for partitioning and the results of different partitioning were compared.With the help of spatial transition matrix,the spatial and temporal patterns of the 5-year zoning results were described quantitatively and qualitatively,and the causes were explored.At the same time,the application of precision management zoning in the practice of black land protection is explored and countermeasures for precision management of cultivated land are put forward to realize the transformation of technical achievements and cultivated land management practice.The results are as follows:(1)There is strong spatial heterogeneity in cultivated land.From the perspective of remote sensing image characteristics,the difference of images in bare soil period is mainly due to the uneven distribution of soil attributes in cultivated land.The difference of image in growing period is due to the different situation of crop growth,which is reflected in remote sensing image as the difference of image characteristics.From the perspective of soil and crop,the physical and chemical parameters of soil and crop have strong variability,and there are great differences in soil and crop parameters at different topographic locations.(2)Introducing terrain factor as input can improve the precision of accurate management zoning.Based on NDVI in the early stage of crop growth in 2020,four terrain factors including elevation,slope,topographic relief and surface roughness were introduced to form six regional input combinations,which were evaluated from two perspectives of soil properties and crop yield.The results show that compared with NDVI zoning alone,the introduction of terrain factors can improve the accuracy of zoning,and the introduction of four terrain factors at the same time has the best effect,followed by the introduction of elevation.The results show that the impact of topographic factors on the results of cultivated land zoning should be fully considered in the precise management of cultivated land zoning,and the accuracy of zoning can be improved by adding topographic factors.(3)The spatial and temporal pattern of precision management of cultivated land in the early stage of crop growth is similar for many years.The NDVI in the first ten days of June from 2017 to2021 was precisely managed and classified,and the spatial transition matrix was calculated after spatial superposition analysis.Results show that the same level of the partition of unit in most of the area between the inter annual turned to the same level,only a few turned to other grades,local differences may be affected by the climate and other factors,but does not affect the overall tendency,namely in the study area accurate management partition results early crop growth,crop looks similar pattern.(4)Terrain is an important factor affecting the results of accurate management zoning.Based on NDVI zoning,in addition to the NDVI variability between zoning units decreased by about70%,the variability of elevation decreased by about 50%,and the variability of slope decreased by about 30%,indicating that terrain has a great impact on the results of accurate zoning management.Soil temperature,humidity and crop growth changed regularly with topography.Soil temperature and soil moisture were the highest on the sunny slope,and the maximum VALUES of NDVI in four periods were also located on the sunny slope.The soil temperature at the top of the slope was higher and soil moisture was the lowest,while the soil moisture at the bottom was higher but soil temperature was the lowest.NDVI value decreased gradually from the top of the slope to the bottom of the slope.This indicates that topography affects crop growth by affecting soil temperature and water redistribution in the early stage of crop growth,and thus affects the results of accurate zoning management.(5)Precision management zoning technology is practical.The land consolidation project based on precise management zoning can reduce manpower and machinery input and improve the efficiency of cultivated land transformation.After paddy field grated field transformation based on precise management zoning,the grated field area increases by more than 2.5% and the utilization rate of cultivated land is improved.The practice of weight loss and drug reduction in cultivated land shows that the precise fertilization and drug application prescription map generated based on the results of precise management zoning can guide agricultural production practice.Fertilizer application was reduced by 10% and yield increased by 14%.The pollution of cultivated land caused by fertilization and pesticide application was reduced,and the economic benefit,ecological benefit and social benefit of cultivated land were improved synchronously.(6)Put forward countermeasures and suggestions for precise management of black soil cultivated land based on precise management zoning technology: Consolidate the technical foundation of precise management zoning,the precision management zoning technology into the air and earth integrated farmland management measurement and control system,strengthen the construction of supporting facilities related to the precise management of cultivated land zoning,take the lead from the Government and co-operatives,promote the positive interaction between technology and cognition.Based on the theory of land zoning utilization,this study explored the possibility of land zoning utilization and management technology.The results are beneficial to the promotion of high-standard farmland construction in northeast China,the implementation of black land protection in Northeast China,the guarantee of grain production,and the realization of the strategic goal of "storing grain in technology".It is of great significance to effectively protect and utilize cultivated land resources,maintain land ecological security,realize high-quality agricultural development and promote rural revitalization strategy. |
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