Geographic variations of aggregate mechanical stability controlled by inorganic cementing agents across the East Asian monsoon region
Xuesong Fan,
Xinliang Wu,
Jinxing Zhou,
Long Wan
Affiliations
Xuesong Fan
State Key Laboratory of Efficient Production of Forest Resources, Beijing Forestry University, Beijing 100083, China; Jianshui Research Station, Key Laboratory of State Forestry Administration on Soil and Water Conservation, Engineering Research Center of Forestry Ecological Engineering, Ministry of Education, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China
Xinliang Wu
State Key Laboratory of Efficient Production of Forest Resources, Beijing Forestry University, Beijing 100083, China; Jianshui Research Station, Key Laboratory of State Forestry Administration on Soil and Water Conservation, Engineering Research Center of Forestry Ecological Engineering, Ministry of Education, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China; National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China; Corresponding author.
Jinxing Zhou
State Key Laboratory of Efficient Production of Forest Resources, Beijing Forestry University, Beijing 100083, China; Jianshui Research Station, Key Laboratory of State Forestry Administration on Soil and Water Conservation, Engineering Research Center of Forestry Ecological Engineering, Ministry of Education, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China
Long Wan
State Key Laboratory of Efficient Production of Forest Resources, Beijing Forestry University, Beijing 100083, China; Jianshui Research Station, Key Laboratory of State Forestry Administration on Soil and Water Conservation, Engineering Research Center of Forestry Ecological Engineering, Ministry of Education, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China
Soil aggregate mechanical properties are of vital importance for plant growth, tillage and soil erosion, and strongly conditioned by the amount and type of cementing agents that differ with soils. As most research focus at the site scale, how aggregate mechanical stability vary across different types of soils at regional scales and underlying mechanisms remain poorly understood. Herein, seven typical zonal soils in heavy textures with an increased status of soil development were collected under two land uses (arable and forest) and at three pedogenic horizons along the mid-temperate to south-subtropical climatic gradient in the East Asian monsoon region. Aggregate tensile strength (Y), specific rupture energy (Esp) and friability (FI) were measured on air-dried aggregates in a compression test, as well as soil cementing agents related to particle size distribution, organic matter and its components, metal oxides, phyllosilicates and exchangeable cations. Y and Esp were most affected by soil type (F = 37.7 and 21.4, p 0.01), suggesting the predominant roles of the inorganic cementing agents in aggregate mechanical stability across soil types. Aggregate mechanical stability was increased by exchangeable polyvalent cations and vermiculite (r = 0.71 ∼ 0.81, p < 0.001), and weakened by crystalline Fe and Al oxides (r = −0.77 ∼ −0.74, p < 0.001). Additionally, mean annual precipitation and temperature were negatively correlated with aggregate mechanical stability (r = −0.80 ∼ −0.76, p < 0.001). This study demonstrates the remarkable geographic variations of aggregate mechanical stability under the influence of climate and highlights the importance of clay mineralogy (mainly swelling clay and crystalline Fe and Al oxides) and exchangeable cations at the regional scale.
