黑土区田块尺度下地形影响作物长势机理分析

Effect of Topography on Crop Growth in Black Soil Area

为揭示作物长势及水肥运移的空间分异规律,探究田块尺度内作物长势与地形变化的关系,以东北典型黑土区东兴农机合作社为研究区,沿南北垄向提取高精度数字高程模型(Digital elevation model,DEM)与归一化植被指数(Normalized differential vegetation index,NDVI)信息,构建地形指标,分析NDVI的空间变异性。结果表明,坡型凸凹程度越明显,NDVI的空间变异性越大;同类坡型中阴坡NDVI的空间变异性与坡型凸凹程度呈负相关;坡度在±0.03范围内,作物长势好,空间变异性低;以坡度绝对值高于0.04的坡度均值与其对应直线距离所占整条直线的比值作为自变量,构建多元逐步回归模型,进行回归分析,可以解释大豆NDVI决定系数为0.9652、高粱NDVI决定系数为0.8883的空间变异性。不同地理空间的地形与成土母质差异显著,通过分析研究区内地形对作物长势的影响规律,可为田块尺度地形的分析提供借鉴,有助于指导农户合理地进行水肥分配。

Aiming to reveal the differentiation of crop growth and water and fertilizer migration by topography,and explore the relationship between crop growth and slope type change in field scale,a cooperative in typical black soil area of Northeast China was selected as the study area to extract high precision digital elevation model(DEM)and normalized differential vegetation index(NDVI)information along the north and south ridges.The spatial variability of NDVI was analyzed by constructing terrain index.The results showed that the more obvious the degree of terrain protruding and concave was,the greater the spatial variability of NDVI was.The NDVI spatial variability of the same slope type was negatively correlated with the degree of protruding and concave of the slope type,and the crop growth was good and the spatial variability was low within the slope of±0.03,and the spatial variability was low.The line scale and slope length were above 0.04,which explained the spatial variability of soybean NDVI of 0.9652(R2)and sorghum NDVI of 0.8883(R2).There were significant differences between topography and soil-forming parent material in different geographical space.Through the analysis between crop growth and topographic conditions in the study area,it provided important reference significance for the analysis of field scale topography,and it can guide farmers to allocate resources reasonably,which had strong practicability.