Technical ArticleAggregate Mechanical Stability and Relationship With Aggregate Breakdown Under Simulated RainfallLi, Zhaoxia1; Yang, Wei2; Cai, Chongfa1; Wang, Junguang1Author Information 1Soil and Water Conservation Research Centre of Huazhong Agricultural University, Wuhan, China. 2Hubei Water Resources Research Institute, Wuhan, China. Address for correspondence: Dr. Chongfa Cai, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, People's Republic of China. E-mail: [email protected] Drs. Zhaoxia Li and Wei Yang contributed equally to this work and should be considered first coauthors. Financial Disclosures/Conflicts of Interest: This work was supported by the National Natural Science Foundation of China (grants 40930529, 41171223, and 41001164). Received December 15, 2012. Accepted for publication July 29, 2013. Soil Science: July 2013 - Volume 178 - Issue 7 - p 369-377 doi: 10.1097/SS.0b013e3182a74255 Buy SDC Metrics Abstract Soil erosion caused by water is a major form of soil degradation. Scientists suggest that this phenomenon can be predicted based on aggregate stability. However, most of these scientists have focused on the water stability of aggregates; only a few have devoted efforts to study the mechanical stability of aggregates. To investigate the relationship of aggregate breakdown with mechanical stability and the possibility of predicting soil erosion based on mechanical stability, we collected eight kinds of Ultisol aggregates (3–5 mm) from subtropical China and exposed these aggregates to simulated rainfall (60 mm h−1). Mean weight diameter (MWD) and splash loss after rainfall were analyzed and compared with aggregate water stability and mechanical stability. Aggregate water stability was determined by wet sieving methods; aggregate mechanical stability was tested by aggregate penetration resistance and tensile strength. Wet sieving method, tensile strength, and penetration resistance of dry aggregates exhibited a good relationship with aggregate MWD (R2 ≥ 0.838, 0.775, and 0.593, respectively) under rainfall and splash (R2 = 0.758, 0.865, and 0.563, respectively). In contrast, no relationship was found between penetration resistance of wet aggregates and MWD or splash. Thus, MWD of wet sieving method and tensile strength were the better indexes that could be used to estimate fragment size distribution and splash detachment. Tensile strength also correlated with clay contents (r = 0.793*), Fed (r = 0.735*), and Feo (r = 0.911**). With further studies, a simpler and faster method could be developed to estimate soil resistance to erosion based on tensile strength in this region. Copyright © 2013 Wolters Kluwer Health, Inc. All rights reserved.