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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Soil, Water & Air Resources Research » Research » Publications at this Location » Publication #340571

Research Project: Managing Carbon and Nutrients in Midwestern U.S. Agroecosystems for Enhanced Soil Health and Environmental Quality

Location: Soil, Water & Air Resources Research

Title: The role of hydraulic connectivity and management on soil aggregate size and stability in the Clear Creek Watershed, Iowa

item WACHA, KENNETH - Orise Fellow
item PAPANICOLAOU, THANOS - University Of Tennessee
item GIANNOPOULOS, CHRISTOS - University Of Tennessee
item ABBAN, BENJAMIN - University Of Tennessee
item WILSON, CHRISTOPHER - University Of Tennessee
item ZHOU, SHENGNAN - University Of Tennessee
item Hatfield, Jerry
item FILLEY, TIMOTHY - Purdue University
item HOU, TINGYU - Purdue University

Submitted to: Geosciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/7/2018
Publication Date: 12/11/2018
Citation: Wacha, K.M., Papanicolaou, A.N.T., Giannopoulos, C.P., Abban, B.K., Wilson, C.G., Zhou, S., Hatfield, J.L., Filley, T.R., Hou, T. 2018. The role of hydraulic connectivity and management on soil aggregate size and stability in the Clear Creek Watershed, Iowa. Geosciences. 8(12).

Interpretive Summary: Soils with high aggregate stability have been found to promote higher yields and be more resistant to erosion. Many methods have been used to assess aggregate strength, but have not looked in detail at the effect of raindrop impact. This study addresses this limitation by developing a method to evaluate aggregate stability against raindrop impact by using a rainfall simulator. Careful attention was placed on controlling the intensity of rainfall and determining the corresponding energy being applied by the raindrops to the soil aggregates. This was done to provide repeatable testing conditions for samples collected from a wide range of farming practices to see how tillage intensity impacts aggregates. Results showed that reduced tillage and no-till samples had higher stability then conventional samples and were comparable to a restored grassland site.

Technical Abstract: This study provides a systematic examination of the role of management practices on the functionality of aggregate size distribution and stability at the hillslope scale in managed landscapes. Soil samples were collected along the downslope flowpathways of representative hillslopes within conservation and conventionally managed fields as well as a restored prairie. Dual-level aggregate testing includes the determination of aggregate size distribution to reflect the degree of mechanized breakdown through various intensities of tillage, and rainfall simulators were used to assess the stability of aggregates against the fluvial process of raindrop impact. The focus is on the small macroaggregates as they best reflect the role of management on aggregate size distribution and stability. Increased tillage perturbations were found to preferentially skew aggregate size distributions towards finer fractions as well as decreased stability. Conservation sites were shown to have comparable stability values as restored grassland sites due to dampened perturbations to the soil and promotion of aggregate stabilization. The stability of aggregates due to raindrop and water impact may also provide some key insight on available size fractions preferentially entrained in various flow conditions.