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

The pedostructure concept characterizes a soil based upon soil structural properties to predict soil-water behavior. The goal of this work was to determine the impact of land management on the measured pedostructure parameters, the quantitative soil structural properties used for modeling soil-water behavior. Soil samples (fine, illitic, mesic, Aquic Hapludalfs and fine, illitic, mesic, Aeric Epiaqualfs) were taken in May 2007 from DeKalb County in northeastern Indiana. The ideal pedostructure parameters were extracted from the continuously measured shrinkage and potential curves from the surface and diagnostic subsurface horizons of two soil series, differing slightly in drainage characteristics, one soil under no-tillage and the other under rotational tillage. 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 oven-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. (C) 2011 Elsevier B.V. All rights reserved.