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Chinese Journal of Applied Ecology ›› 2020, Vol. 31 ›› Issue (10): 3404-3412.doi: 10.13287/j.1001-9332.202010.025

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Effects of biological soil crusts on solute transport characteristics of sandy and loessal soils on the Loess Plateau, China

WANG Fang-fang1,2, XIAO Bo1,2,3*, SUN Fu-hai1,2, LI Sheng-long1,2   

  1. 1College of Land Science and Technology, China Agricultural University, Beijing 100193, China;
    2Key Laboratory of Arable Land Conservation in North China, Ministry of Agriculture and Rural Affairs, Beijing 100193, China;
    3State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences, Yangling 712100, Shaanxi, China
  • Received:2020-04-13 Accepted:2020-08-10 Online:2020-10-15 Published:2021-04-15
  • Contact: * E-mail: xiaobo@cau.edu.cn
  • Supported by:
    National Natural Science Foundation of China (41671221) and the “Light of West China” Program of the Chinese Academy of Sciences (2019).

Abstract: Biological soil crusts (BSCs) greatly change surface soil structure and nutrient enrichment processes in arid and semiarid regions. However, their impacts on solute transport characteristics and nutrient loss are still not clear. In this study, the solute (Cl- and Ca2+) transport experiments were conducted on soils covered by moss-dominated BSCs and uncrusted soil on sandy and loessal soils on the Loess Plateau, respectively. We analyzed the solute transport characteristics of the BSCs covered soil and uncrusted soil in different soil depths (0-5 cm and 5-10 cm). The BSCs mulching generated delay effects on the solute breakthrough process of 0-5 cm soils. The breakthrough time of Cl- in the BSCs covered soil was 3.83 (sandy soil) and 2.09 times (loessal soil) longer than that in the uncrusted soil. The breakthrough time of Ca2+ in the BSCs covered soil was 2.50 and 2.73 times longer than that in the uncrusted soil. Due to the strong influence of BSCs mulching, the pore volume number of the complete solute breakthrough at 0-5 cm depth was higher than that at 5-10 cm depth in the BSCs covered soils. The breakthrough time of Cl- at 0-5 cm depth was increased by 67.3% (sandy soil) and 51.8% (loessal soil) by the BSCs as compared with that at 5-10 cm depth. The breakthrough time of Ca2+ at 0-5 cm depth was increased by 8.0% and 33.7% by the BSCs. The BSCs reduced soil pore water flow velocity by 37.5%-70.2% compared with the uncrusted soil. Except for the sandy soil at 5-10 cm depth, the BSCs increased the solute dispersion coefficient by 1.73-6.29 times and the degree of dispersion by 2.77-20.95 times compared with the uncrusted soils. After the complete breakthrough of solute, the content of Ca2+ in the BSCs layer (0-2 cm) was 4.14 and 2.58 times higher than that in the uncrusted sandy and loessal soils, respectively. In conclusion, our results indicated that BSCs could reduce the deep percolation and loss of nutrients accumulated in surface soil through improving their solute adsorption and retention abilities, which is of great significance for the improvement of soil fertility and vegetation restoration on degraded land in arid and semiarid regions.

Key words: breakthrough curve, CDE equation, sandy soil, loessal soil, adsorption