Apparent soil electrical conductivity in two different soil types

ABSTRACT Mapping the apparent soil electrical conductivity (ECa) has become important for the characterization of the soil variability in precision agriculture systems. Could the ECa be used to locate the soil sampling points for mapping the chemical and physical soil attributes? The objective of this work was to examine the relations between ECa and soil attributes in two fields presenting different soil textures. In each field, 50 sampling points were chosen using a path that presented a high variability of ECa obtained from a preliminary ECa map. At each sampling point, the ECa was measured in soil depths of 0-20, 0-40 and 0-60 cm. In addition, at each point, soil samples were collected for the determination of physical and chemical attributes in the laboratory. The ECa data obtained for different soil depths was very similar. A large number of significant correlations between ECa and the soil attributes were found. In the sandy clay loam texture field there was no correlation between ECa and organic matter or between ECa and soil clay and sand content. However, a significant positive correlation was shown for the remaining phosphorus. In the sandy loam texture field the ECa had a significant positive correlation with clay content and a significant negative correlation with sand content. The results suggest that the mapping of apparent soil electrical conductivity does not replace traditional soil sampling, however, it can be used as information to delimit regions in a field that have similar soil attributes.

摘要：表观土壤电导率（apparent soil electrical conductivity，ECa）的测绘已成为精准农业系统中土壤变异性表征的重要手段。能否利用ECa确定土壤采样点位，以测绘土壤的化学与物理属性？本研究旨在探究两块不同质地农田中ECa与土壤属性之间的关联关系。每块农田均沿初步ECa测绘图中ECa变异性较高的路径，选取50个采样点位。在每个采样点位，分别测定0~20 cm、0~40 cm及0~60 cm土层的ECa数值；此外，在每个采样点位采集土壤样本，送至实验室测定其物理与化学属性。不同土层测得的ECa数据具有高度相似性，且ECa与诸多土壤属性间存在显著相关性。在砂质粘壤土质地的农田中，ECa与有机质、土壤粘粒及砂粒含量均无显著相关性，但与残留磷含量呈显著正相关。在砂壤土质地的农田中，ECa与粘粒含量呈显著正相关，而与砂粒含量呈显著负相关。研究结果表明，表观土壤电导率测绘虽无法替代传统土壤采样，但可作为划分农田内土壤属性相似区域的参考依据。