Soil Hydraulic Properties of Plinthosol in the Middle Yangtze River Basin, Southern China

Soil hydraulic properties are ecologically important in arranging vegetation types at various spatial and temporal scales. However, there is still a lack of detailed understanding of the basic parameters of plinthosol in the Middle Yangtze River basin. This paper focuses on the soil hydraulic properties of three plinthosol profiles at Yueyang (YE), Wuhan (WH), and Jiujiang (JU) and tries to reveal the origin of plinthosol and the relationship among the soil hydraulic parameters. Discriminant analysis indicated that the plinthosol in the JU profile was of aeolian origin, while that in the WH and YE profiles was of alluvial origin; soil hydraulic properties varied greatly among these profiles. The proportion of macro-aggregates (>0.25 mm, weight%) in the JU profile (88.28%) was significantly higher than that in the WH (73.63%) and YE (57.77%) profiles; the water holding capacity and saturated hydraulic conductivity of JU plinthosol was also higher than that of WH and YE plinthosol; the fact thatD(r)andD(i)of the JU profile are lower than those of the YE and WH profiles illustrates the stability of JU plinthosol is better than that of YE and WH plinthosol, which is consistent with the fractal dimension of aggregates. The disintegration curves of white vein and red matrix demonstrated a large discrepancy in the JU profile, but these curves showed a similar trend in the WH and YE profiles. The differences in hydraulic properties might be ascribed to the origin of plinthosol, and the results of the fractal dimension also confirmed this conclusion. This study might provide a better understanding of the soil physical properties of plinthosol and shed light on the soil and water conservation measures in the Middle Yangtze River basin.