Author
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Benjamin, Joseph |
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Mikha, Maysoon |
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Submitted to: Book Chapter
Publication Type: Book / Chapter Publication Acceptance Date: 1/20/2009 Publication Date: 6/21/2010 Citation: Benjamin, J.G., Mikha, M.M. 2010. Predicting Winter Wheat Yield Loss from Soil Compaction in the Central Great Plains of the United States. Book Chapter:Land Degradation and Desertification: Assessment, Mitigation and Remediation 49:649-656. Doi: 10.1007/978-90-481-8657-0. Interpretive Summary: Knowledge of resistance of near-surface soil aggregates to erosive forces of wind and rain is critical in determining the extent to which a soil will erode. Objectives of this study were to quantify changes in aggregate properties (e.g., size distribution, stability, resistance to raindrops, and wettability) and study their relationships to soil organic carbon concentration under various long-term tillage systems in the Central Great Plains. Three long-term tillage systems (conventional tillage, reduced tillage, and no-till) were studied at four sites across the central Great Plains: Hays and Tribune, KS, Akron, CO, and Sidney, NE. Aggregates from no-till soils were more stable under rain and less wettable than those from plowed soils, particularly at the soil surface. Soil organic carbon concentration explained 35% of the variability across soils in aggregate wettability and 28% of the variability in resistance to raindrops. Aggregates in conventionally tilled soils were either stronger than or equally as strong as those in no-till soils when dry, but were less stable when wet. This regional study shows that no-till farming has large and positive effects on improving soil structural properties and reducing soil water erodibility, even if surface crop residue levels are sparse. But effects of no-till on aggregate properties influencing wind erosion appear to be limited; adequate surface crop residue levels must be maintained for no-till to reduce wind erosion. The ability of no-till to control water erosion has enormous implications because intense rainstorms can cause large losses of soil in semiarid regions. Increasing soil organic concentration through no-till and other best management practices is crucial for reducing soil erosion while improving soil quality and sustaining crop production. Technical Abstract: The extent to which no-till management improves water and wind erodibility parameters is not well understood. This study assessed changes in aggregate resistance to raindrops, dry aggregate wettability, and dry aggregate stability as well as their relationships with changes in soil organic carbon concentration in the central Great Plains. Three longterm tillage systems (conventional tillage, reduced tillage, and no-till) were studied at four sites across the central Great Plains: Hays and Tribune, KS, Akron, CO, and Sidney, NE. The kinetic energy of simulated raindrops required to disintegrate 4.75- to 8-mm aggregates from no-till soils was between two and seven times greater than that required for conventionally tilled soils in the 0- to 1-in. depth in all soils. No-till soils delayed water entry into aggregates by four times at Akron and Hays and by seven times at Sidney and Tribune compared with plowed soils. Aggregates from no-till soils were more stable under rain and less wettable than those from plowed soils, particularly at the soil surface. Reduced tillage had lesser beneficial effects than no-till management. Soil organic carbon concentration explained 35% of the variability across soils in aggregate wettability (a measure of how readily aggregates can repel water) and 28% of the variability in resistance to raindrops. Tillage system did not affect dry aggregate size distribution and stability. Aggregates in conventionally tilled soils were either stronger than or equally as strong as those in no-till soils when dry but were less stable when wet. Overall, no-till farming enhanced near-surface aggregate properties affecting water erosion but had small or no effects on dry aggregate stability. |
