单 位：
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China);Jiangxi Agricultural University, Nanchang 330045 (China); University of Chinese Academy of Sciences, Beijing 100081 (China);State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); University of Chinese Academy of Sciences, Beijing 100081 (China
摘 要：
Different pore sizes present different pore shrinkage capacities in a nonrigid soil. However, the shrinkage capacities of different pore sizes and their influencing factors are not clear. We aimed to quantify the shrinkage capacities of different pore sizes (large pores, >50 μm; medium pores, 0.2–50 μm; fine pores, <0.2 μm) and to determine how soil properties impact shrinkage at the regional scale. Two sampling transects from west to east (360 km long, 35 samples) and from north to south (190 km long, 29 samples) were selected to investigate the shrinkage capacity and physicochemical properties of soils in the 0–20 cm soil layer in the Vertisol (locally known as Shajiang black soil) region of the North China Plain. The results showed that total shrinkage capacity, indicated by the coefficient of linear extensibility (COLE), had a mean value of 0.041–0.051 in the east–west and north–south transects. Large pores had higher pore shrinkage index (PSI) values (0.103–0.109) than medium (0.077–0.096) and fine (0.087–0.091) pores. The PSI of fine pores showed a fluctuating increasing trend from northwest to southeast, and the shrinkage capacity determined the COLE (R2 = 0.789, P < 0.001). The PSI of large pores had a significant relationship with the soil bulk density (R = 0.281, P < 0.05) and organic carbon (SOC, R = -0.311, P < 0.05), whereas that of medium and fine pores was correlated with the clay content (R = 0.381, P < 0.01; R = 0.687, P < 0.001, respectively). In addition, the PSI of the fine pores was also correlated with montmorillonite content (R = 0.387, P < 0.01). It can be concluded that the PSI of large pores is related to anthropogenically influenced soil properties with low stability, whereas that of medium and fine pores is related to pedogenic properties. The high variability in anthropogenic and pedogenic factors explains the spatial pattern of Vertisol shrinkage capacity in the North China Plain.
