利用GIS模拟变量施肥尺度对施肥量的影响研究

Using GIS to Study Relationship between Fertilization Amount and Management Zone Size on Variable-Rate Fertilization

以玉米氮肥变量施肥为例，采用GIS技术分别模拟不同肥力水平、不同空间变异和不同相关距条件下变量施肥尺度对施肥量的影响．首先用“Turning Band Method”方法随机生成符合指定均值、方差和空间分布（半方差模型）的一组表示最小施肥单元的土壤养分数据，每组10^4个数据，对每组数据进行了100个等级尺度单元的相关施肥量计算和分析．模拟结果表明：（1）随着变量施肥单元面积减小，施肥量不是减少，而是增加或保持不变；（2）相同土壤肥力，空间变异越大时，随着施肥尺度增大，平均施肥量增大越明显，而且施肥临界养分过渡带的变量施肥合理性受尺度影响最大．

In this study, the authors use GIS to simulate the relationship between Fertilizer Amount and management zone size on variable-rate fertilization under different Soil Nitrate Levels, Spatial-Variability and Spatial Autocorrelated Ranges. Field distribution dataset series of soil nitrate concentration in 500×500m^2 field were generated based on given mean, standard deviation and related distance. Each dataset is composed of nitrate concentration values at 104 cells, with cell size of 5×5 m^2. The amount of fertilization and yield from scale 100 to 1 were then calculated based on the generated soil nitrate distribution. The results show that when the size of management zone increases, precise fertilization will increase the amount of fertilization, the fertilization precision becomes lower, and the negative effect of fertilization on environment becomes larger. As the management zone size for variant rate fertilization becomes lager, the fertilization is more unreasonable, and the unreasonable fertilization area distribute in the area where the soil nitrate concentration is near transition point for fertilization.