雷达探测分析下的广西蔗田土壤优先流空间分布

Spatial distribution of preferential flow in sugarcane field in Guangxi under radar detection

以广西垄耕和免耕两种处理方式下的甘蔗地为对象,将染色示踪与雷达探测技术相结合,通过染色图像形态分析与雷达图像信息解译,以及Logistic回归分析等方法对不同耕作方式下甘蔗地的土壤优先流空间分布变化及其影响因素进行研究。结果表明:土壤介电常数和雷达剖面图像幅值随土壤深度呈现先增大后减小的变化趋势,介电常数在不同土壤深度存在显著性差异(P<0.05),免耕耕作方式下在20-50 cm土壤深度仍有幅值变动区域,变化范围在-0.3×10^(6)-0.3×10^(6),表明免耕方式下水分发生垂向运动;垄耕甘蔗地的电磁波幅值变动集中在0-20 cm土壤深度,优先流多为横向运动,波峰与波谷间变动值为0.27,小于免耕甘蔗地的变动值(0.34),二者电磁波幅值变动存在显著性差异(P<0.05);饱和导水率和有机质含量是雷达探测下优先流发育的主要影响因素。雷达探测可定量表征土壤中的优先流空间分布情况,垄耕在一定程度上降低了蔗田土壤水分的快速运移,提高了田间保水蓄水状况。

Based on the combination of dye tracer and radar detection technology,the spatial distribution patterns and influencing factors of soil priority flow in sugarcane fields under ridge tillage and no-tillage treatments in Guangxi were examined by morphological analysis of dye image,interpretation of radar image information,and Logistic regression analysis.The results showed that soil dielectric constant and radar profile image amplitude showed a trend of first increasing and then decreasing with soil depth,and that the dielectric constant was significantly different among soil depths(P0.05).Under no-tillage,the soil layer of 20-50 cm had a range of amplitude variation,with a variation range between-0.3×10^(6) and 0.3×10^(6),which indicated that water moved vertically.The fluctuation of electromagnetic wave amplitude in ridge-cultivated sugarcane fields was concentrated in the soil layer of 0-20 cm,and the preferential flow was mostly lateral movement.The change value between the peak and the nadir was 0.27 under ridge tillage,which was smaller than that under no-tillage(0.34)(P0.05).Saturated hydraulic conductivity and organic matter content were the main factors affecting the development of preferential flow under radar detection.Radar detection can quantitatively characterize the spatial distribution of preferential flow in the soil.Ridge tillage can reduce the rapid migration of soil water in sugarcane fields to a certain extent,and enhance water retention and storage conditions in the fields.