Santos, D., S. L. Murphy, H. Taubner, A. J. Smucker, and R. Horn. 1997. Uniform separation of concentric surface layers from soil aggregates. Soil Science Society America Journal 61:720-724.

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It is well accepted that soil organic matter improves soil structure; however, current methods limit our knowledge of the many physical-chemical mechanisms that control the temporal processes of soil aggregation. A soil aggregate erosion (SAE) apparatus was designed to uniformly remove concentric surface layers of soil aggregates in an enclosed erosion chamber. The SAE was used to test for the presence of concentration gradients within aggregates of different soil types. The SAE method generally improved the separation of ion concentrations between the external and internal layers. Concentrations of C, Ca, and Mg were 8 to 19, 20 to 21, and 29 to 33% lower, respectively, at the external layers of aggregates for Haplaquoll and Hapludalf soils. Removal of surface layers had no effect on the tensile strength of soil aggregates. Therefore, we concluded that the SAE apparatus improves the separation of ion gradients within natural soil aggregates. Identification of the mineralogical, physical, chemical, and biological properties of this improved separation of concentric layers from soil aggregates should lead to further advancements in our knowledge of the functional mechanisms associated with the development and stability of soil aggregates.

DOI: 10.2136/sssaj1997.03615995006100030003x

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