黄河三角洲夏季典型田块土壤盐分的多尺度空间变异

土壤盐渍化严重阻碍黄河三角洲农业经济发展,掌握田间多尺度下土壤盐分的空间变异性特征对于盐渍土改良利用和农业生产有重要意义。选取黄河三角洲垦利区代表性夏季玉米田块,划分为大田、地块、垄间3个尺度,通过实地调查采样获取152 组电导率数据,运用经典统计学、地统计学和克里格插值方法,分析多尺度下田块土壤盐分的空间变异性特征及其尺度效应。结果表明: 试验区土壤为中度盐渍化,土壤盐分在3种尺度下均呈中等强度变异,从大田、地块到垄间,随着采样尺度的减小,土壤盐分的变异性趋强、标准差增大;垄间和地块尺度表现为强空间相关性,最优拟合模型为高斯模型,主要受结构性因素影响,大田尺度为中等空间相关性,最优拟合模型为指数模型,受随机性因素和结构性因素共同影响;不同尺度土壤盐分的空间分布特征有明显差异,小尺度的空间特征在大尺度下被掩盖,存在明显的尺度效应;垄间微域尺度下土壤盐分分布变异明显,土壤含盐量随微地貌由高到低、植被覆盖由疏至密而逐渐降低。

Multi-scale spatial variability of soil salinity in typical fields of the Yellow River Delta in summer

Soil salinization severely hinders the development of agricultural economy in the Yellow River Delta. Clarifying the spatial variability of soil salinity at multiple scales in the field is of great significance for the improvement and utilization of saline soils and agricultural production. In this study, by dividing the three dimensions of field, plot and ridge, we collceted 152 sets of conducti-vity data through field survey sampling in a summer maize field in Kenli County of the Yellow River delta. The methods of classic statistics, geostatistics and Kriging interpolation were used to analyze the spatial variability and scale effects of multi-scale soil salt in the field. The results showed that soil in this area was moderately salinized, with the extent of soil salinity moderately varying at three scales. From the field, plot to the ridge scale, with the decreases of sampling scale, the variability of soil salinity increased and the standard deviation increased. The ridge and plot scales showed strong spatial correlation. The optimal model was Gaussian model, which was mainly affected by structural factors. The field scale was of medium spatial correlation, with exponential model as the optimal one, which was influenced by both random factors and structural factors. The spatial distribution characteristics of soil salinity at different scales were significantly different. The spatial chara-cteristics at small scale were masked at large scale, showing obvious scale effect. The distribution of soil salinity at the micro-ridge scale between ridges had obvious variation. Soil salt content gradually decreased with the micro-topography from high to low, while vegetation coverage changed from sparse to dense.