土地利用方式对喀斯特峡谷区土壤水稳性团聚体的影响

目的]全面评价土地利用方式对喀斯特峡谷区土壤结构退化的影响.方法]采用空间代替时间的方法,开展了不同土地利用方式对土壤水稳性团聚体分布特征及稳定性的研究.结果]①不同土地利用方式均以＞0.25 mm粒径水稳性团聚体为主,其量变化、MWD、GMD均表现为林草间作地＞荒草地＞退耕还草地＞耕地;②在不同土层中,不同土地...

The Effects of Land Usage on Water-stable Soil Aggregates in Karst Canyon Region

【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.