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Acta Prataculturae Sinica ›› 2020, Vol. 29 ›› Issue (12): 38-49.DOI: 10.11686/cyxb2020315

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Chemical weathering characteristics of calcareous soil under different land-use patterns in a Karst mountainous area

Peng-peng ZHOU(), Ying-ge SHU(), Zhong-liu CHEN, Qing-song CHEN   

  1. College of Agriculture,Guizhou University,Guiyang 550025,China
  • Received:2020-07-06 Revised:2020-08-25 Online:2020-12-28 Published:2020-12-28
  • Contact: Ying-ge SHU

Abstract:

We determined the chemical weathering characteristics of calcareous soil profiles under different land-use patterns [cultivated land (CL), wild grassland (WGL), returning farmland to grassland (RFL) and forest and grass intercropping (FGL)] in the Karst mountainous area. The distribution, migration, and enrichment of mineral elements in calcareous soil profiles were analyzed, and the chemical weathering characteristics of soil under different land-use patterns were determined by measuring the soil weathering degree, element leaching degree, migration degree, and residual degree. It was found that the main oxides in the limestone profile in the Karst mountainous area were SiO2, Al2O3, and Fe2O3, with smaller amounts of other oxides (medium-variable elements). Comparing soils from areas with different land-use patterns, WGL soil was richer in SiO2, Al2O3, and MgO; FGL soil was richer in CaO and Na2O; and CL soil was richer in Fe2O3, MnO, P2O5 and K2O. The soil in the study area was in the middle chemical weathering stage, with a weak degree of aluminization. The chemical alteration coefficient of the soil in desert grassland was stronger under certain land-use patterns. Aluminization was strongest in FGL soil. Leaching of soil K, Na, and Ca was severe in the study area, and leaching of salt ions was more obvious in barren grasslands. The strength of leaching of salt ions was relatively low in FGL soil. Soils had relatively high Fe and Al contents, especially Al in FGL soil and Fe in RFL soil. The implementation of governance models such as returning farmland to grassland to increase vegetation cover will significantly affect soil protection. These findings provide a scientific basis and theoretical guidance for understanding the formation and evolution of lime soil in the Karst mountainous area, soil degradation mechanisms, soil management and land-use countermeasures, ecological restoration, and soil and water conservation in ecologically vulnerable Karst areas.

Key words: mineral elements, chemical weathering, calcareous soil, the Karst mountainous area, different land use patterns