|Huang, Chi hua|
Submitted to: Advances in Geoecology
Publication Type: Book / chapter
Publication Acceptance Date: 7/10/2006
Publication Date: 8/1/2006
Citation: Norton, L.D., Mamedov, A., Huang, C., Levy, G. 2006. Soil aggregate stability as affected by long-term tillage and clay type. In: Horn, R., Fleige, H., Peth, S. and Peng. X., editors. Soil Management for Sustainability. Advances in GeoEcology 38. ISBN 3-923381-52-2, US ISBN 1-59326-246-9. Reiskirchen, Germany: Catena Verlag p. 422-429. Interpretive Summary: Soil sealing and crusting is a major problem leading to high runoff rates and soil erosion, poor seedling emergence, and poor exchange of gases, all of which may affect crop yields. We studied soils from the USA and Israel with a wide range of the type of clays to determine if this affected the aggregate stability of the soil and resistence to sealing. We used a very sensitive method to evaluate differences in soil aggregate structural stability as it varied with clay type. We found that soils that had not been cultivated or soil containing an appreciable amount of kaoline were more stable than soils with swelling clays. Long-term no-tilling decreased the amount of pores allowing water to be taken in and reduced the stability of soil aggregates. We found that both tillage history and the type of clay should be considered when managing soils to prevent surface sealing and to control erosion. The significance of this work is that we can utilize soil information of soil composition and history of cultivation to taylor our management strategies to prevent the adverse affects of surface sealing and to control soil erosion more effectively.
Technical Abstract: Soil aggregate stability and dispersivity depend on clay mineralogy. However, little is known about the effect of soil mineralogy on soil crustability for long-term cultivated soil. The effect of long-term tillage on aggregate stability was the objective of our study. More than 20 soil samples characterizing a range of important agricultural (virgin, long-term no-till and tilled) soils of the humid and semi-arid zones with predominantly illitic, smectitic and kaolinitic clay mineralogy were studied. We measured aggregate stability using the high energy moisture characteristic method (HEMC), where the destructive force used to break down aggregates was accurately controlled by either a slow or fast wetting rate. Stability ratio was calculated from the changes in pore size distribution following the wetting as it was a sensitive measure of stability. The virgin soils, and soils predominantly with kaolinitic mineralogy were more stable independent of texture. Long-term tillage was more effective (harmful) for illitic and smectitic soils, whereas, effect of long-term no-till mostly were valuable on these soils with a relative high clay content. Long-term tillage significantly decreased volume of infiltration (drainable) pores, structural index and aggregate stability (10-30%). The aggregate stability indices were correlated with previously published seal formation data. Generally correlation was well with soil clay and/or organic matter content, seal formation and erosion data. Soil mineralogy should be considered on runoff and erosion prediction. The mechanisms describing the effect of soil mineralogy and texture and tillage and their interaction on aggregate stability, runoff and erosion are discussed.