川中紫色丘区土壤养分空间分异与地形因子相关性研究

Correlations between Spatial Variability of Soil Nutrients and Topographic Factors in the Purple Hilly Region of Sichuan

研究地形因子与土壤养分空间分异的相关关系对于养分管理和精准农业都具有一定指导意义。应用GIS技术结合地统计方法,研究川中紫色丘陵区土壤养分空间分异性,探讨坡位、坡度、坡向和坡形4个地形因子及其不同组合与土壤养分空间分布的相关性。结果表明:①研究区土壤养分均呈现中等变异;②土壤养分因子与高程、坡度、坡形呈负相关;与坡向、平面曲率和剖面曲率呈正相关;③4个地形因子中,坡位、坡度及坡向对土壤养分分布具有强烈影响。坡位-坡度组合下,土壤养分分异与在坡位和坡度单个因子作用下趋于一致,但差异不显著。坡位-坡向组合下,土壤养分分异主要与坡向相关。坡度-坡向组合下,土壤碱解氮和有机质随坡向变异明显,而速效磷和速效钾则随坡度变异明显;④Kriging插值显示,有机质在中部丘顶部位含量最低,随坡位下降含量呈环状升高;碱解氮主要分布于区域西北部;速效磷在空间分布上沿西北-东南方向呈现一条高含量带;而速效钾则主要分布于区域西南部,以中部三处丘顶含量最低,呈环状逐步向外增高。

The relationship between topographic factors and the spatial variability of soil nutrients is significant to nutrient management and precision agriculture. Here, geo-statistics and GIS technology were applied to the Purple Hilly Area to explore the relationship between soil nutrient and slope position, slope, slope aspect, slope shape and combinations thereof. Results indicated moderate variability in soil nutrients across the study area. Soil nutrients were negatively correlated to elevation, slope and slope shape, and positively correlated to slope aspect, plan curvature and profile curvature. In addition, among the four topographic factors, slope position, slope and slope aspect have a strong impact on the spatial distribution of soil available nutrients. Spatial variability of soil nutrients was mainly related to the slope aspect under the influence of the combination of slope position-slope aspect but converged with a single factor under the influence under the combination slope position-slope, but the difference was not significant. Under the influence of the combination slope-slope aspect, significant variation with slope aspect for soil organic matter and soil available nitrogen and variation with slope for soil available P and available K were found. Briefly, interpolation by kriging indicated that soil organic matter reached the lowest at the central hill top site and soil available nitrogen content was mainly distributed northwest of the study area. The spatial distribution of available P showed a high level along the northwest-southeast direction. Additionally, the spatial distribution of available K was mainly distributed in the southwest, and the three lowest content sites were in the central hill top site.