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| DOI：10.13522/j.cnki.ggps.2020600 |
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| The Effects of Land Usage on Water-stable Soil Aggregates in Karst Canyon Region |
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XIAO Shengyang, SHU Yingge
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1.Institute of Mountain Resources, Guiyang 550001, China; 2.College of Agriculture, Guizhou University, Guiyang 550025, China
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| Abstract: |
| 【Objective】Aggregate is a basic functional unit in soil to characterize the impact of soil structure on soil functions. It changes with agricultural practice and land management. The aim of this paper is to investigate the impact of land usage on water-stable aggregates in Karst Canyon regions.【Method】Space-for-time method was used to study distribution and stability of water-stable aggregates under four land managements: forest and grassland, grassland, turning farmland to grassland, and cultivated agricultural land.【Result】The aggregate sizes in all land managements were larger than 0.25 mm although the aggregate fractions varied between treatments. The MWD and GMD were ranked in the order of: forest and grass>grassland>returning farmland to grassland>cultivated agricultural land, as opposed to the FD. Regardless of soil depth and land management, the volumetric fraction of water-stable aggregates increased with their size first, followed by a decline before increasing again. In particular, in the 0~20 cm soil, the distribution of aggregates sizes and its stability is positively correlated. The critical aggregate size separating micro aggregates and large aggregates was 5 mm. GMD can be used as an index for evaluating stability of water-stable aggregates.【Conclusion】Forest-grass land enhanced the stability of soil aggregates in the Karst canyon region and plays an important role in preventing soil structure degradation. |
| Key words: land usage; water-stable aggregates; stability indexes; karst canyon region |
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