Zhengying Wang;Shu Qin;Lingling Xie;Zuoxin Liu;Bing Chen

Graduate University of Chinese Academy of Sciences, Beijing 100039 (China);Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016 (China); Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016 (China);Liaoning Institute of Soil and Water Conservation, Chaoyang 122000 (China);Department of Soil Science, University of Saskatchewan, Saskatoon, SK, S7N 5A8 (Canada

clay content;multiple scales;correlated;scale;soil water;paramete

Soil water-retention characteristics at measurement scales are generally different from those at application scales, and there is scale disparity between them and soil physical properties. The relationships between two water-retention parameters, the scaling parameter related to the inverse of the air-entry pressure (alpha(vG), cm(-1)) and the curve shape factor related to soil pore-size distribution (n) of the van Genuchten water-retention equation, and soil texture (sand, silt, and clay contents) were examined at multiple scales. One hundred twenty-eight undisturbed soil samples were collected from a 640-m transect located in Fuxin, China. Soil water-retention curves were measured and the van Genuchten parameters were obtained by curve fitting. The relationships between the two parameters and soil texture at the observed scale and at multiple scales were evaluated using Pearson correlation and joint multifractal analyses, respectively. The results of Pearson correlation analysis showed that the parameter alpha(vG) was significantly correlated with sand, silt, and clay contents at the observed scale. Joint multifractal analyses, however, indicated that the parameter alpha(vG) was not correlated with silt and sand contents at multiple scales. The parameter n was positively correlated with clay content at multiple scales. Sand content was significantly correlated with the parameter n at the observed scale but not at multiple scales. Clay contents were strongly correlated to both water-retention parameters because clay content was relatively low in the soil studied, indicating that water retention was dominated by clay content in the field of this study at all scales. These suggested that multiple-scale analyses were necessary to fully grasp the spatial variability of soil water-retention characteristics.