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United States Department of Agriculture

Agricultural Research Service

Research Project: CONSERVATION EFFECTS ASSESSMENT FOR THE ST. JOSEPH RIVER WATERSHED

Location: National Soil Erosion Research Lab

Title: Evaluating the effect of tillage on soil structural properties using the pedostructure concept

Authors
item Mallory, J -
item Mohtar, R -
item Heathman, Gary
item Schulze, D -
item Braudeau, E -

Submitted to: Geoderma
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 31, 2011
Publication Date: May 19, 2011
Repository URL: http://hdl.handle.net/10113/50063
Citation: Mallory, J.J., Mohtar, R.H., Heathman, G.C., Schulze, D.G., Braudeau, E. 2011. Evaluating the effect of tillage on soil structural properties using the pedostructure concept. Geoderma. 163:141-149.

Interpretive Summary: As water supplies across the globe continue to dwindle in the face of the growing uses for population, industry, and agriculture, improved methods of soil-water modeling are needed to protect water resources still available. The pedostructure concept is a new paradigm of soil-water modeling that predicts soil-water behavior using physically-based equations based upon soil structure. Fifteen unique pedostructure parameters are extracted using a soil’s continuously measured shrinkage, potential, conductivity, and swelling curves. The purpose of this work is to determine an accurate means of estimating the physically-based parameters of the pedostructure concept using common soil information and discover how land use affects these parameters. By understanding and accounting for the physical processes that occur between the water, air, and soil solids at the soil aggregate scale, the pedostructure concept is more able to accurately model the soil-water medium as well as scaling behaviors and processes between various spatial levels. Future work includes incorporating discontinuous soil features, such as cracks, into the pedostructure model.

Technical Abstract: The pedostructure (PS) concept is a physically-based method of soil characterization that defines a soil based on its structure and the relationship between structure and soil water behavior. There are fifteen unique pedostructure parameters that define the macropore and micropore soil water behavior for an individual soil. These fifteen parameters are extracted in the laboratory from the continuously measured shrinkage, swelling, potential, and conductivity curves of undisturbed soil cores. Additionally, the pedostructure parameters were estimated from measured and estimated soil physical properties. Three of the seven pedostructure parameters: W**m (saturated micropore water content), K**bs (micropore linear shrinkage rate), and V**o (soil specific volume at the dry state) were significantly different due to the tillage treatment, while none of the parameters exhibited any significant differences due to depth. V**o also showed a significant interaction between tillage and depth, as the rotational tillage subsurface samples had much lower values than other combinations of tillage and depth. Overall, no-tillage exhibits a larger amount of micropores, as evidenced by the higher W**m value, as well as a more strongly structured micropore system, as seen in the lower K**bs, compared to rotational tillage. However, no significant differences exist when estimating the pedostructure parameters from measured and estimated soil physical properties. No significant differences were found for the macropore parameters. These results are unexpected, as it was believed that the no-tillage treatment would affect the macropore, and not the micropore, parameters.

Last Modified: 4/21/2014
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