Wang Fang-Fang, Xiao Bo, Sun Fu-Hai, Li Sheng-Long
College of Land Science and Technology, China Agricultural University, Beijing 100193, China.
Key Laboratory of Arable Land Conservation in North China, Ministry of Agriculture and Rural Affairs, Beijing 100193, China.
Ying Yong Sheng Tai Xue Bao. 2020 Oct;31(10):3404-3412. doi: 10.13287/j.1001-9332.202010.025.
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 Ca) 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 Ca 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 Ca 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 Ca 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.
生物土壤结皮（BSCs）极大地改变了干旱和半干旱地区的表层土壤结构及养分富集过程。然而，它们对溶质运移特征和养分流失的影响仍不明确。在本研究中，分别在黄土高原的沙地和黄土上，对以苔藓为主的生物土壤结皮覆盖的土壤和未结皮土壤进行了溶质（Cl和Ca）运移实验。我们分析了不同土壤深度（0 - 5厘米和5 - 10厘米）下生物土壤结皮覆盖土壤和未结皮土壤的溶质运移特征。生物土壤结皮覆盖对0 - 5厘米土壤的溶质突破过程产生了延迟效应。生物土壤结皮覆盖土壤中Cl的突破时间分别比未结皮土壤长3.83倍（沙地）和2.09倍（黄土）。生物土壤结皮覆盖土壤中Ca的突破时间分别比未结皮土壤长2.50倍和2.73倍。由于生物土壤结皮覆盖的强烈影响，生物土壤结皮覆盖土壤中0 - 5厘米深度处溶质完全突破时的孔隙体积数高于5 - 10厘米深度处。与5 - 10厘米深度相比，生物土壤结皮使0 - 5厘米深度处Cl的突破时间分别增加了67.3%（沙地）和51.8%（黄土）。生物土壤结皮使0 - 5厘米深度处Ca的突破时间分别增加了8.0%和33.7%。与未结皮土壤相比，生物土壤结皮使土壤孔隙水流速降低了37.5% - 70.2%。除5 - 10厘米深度的沙地外，与未结皮土壤相比，生物土壤结皮使溶质扩散系数增加了1.73 - 6.29倍，分散程度增加了2.77 - 20.95倍。溶质完全突破后，生物土壤结皮层（0 - 2厘米）中Ca的含量分别比未结皮的沙地和黄土土壤高4.14倍和2.58倍。总之，我们的结果表明，生物土壤结皮可以通过提高其溶质吸附和保留能力来减少表层土壤中积累的养分的深层渗漏和流失，这对于干旱和半干旱地区退化土地的土壤肥力改善和植被恢复具有重要意义。
