Author
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Lindstrom, Michael |
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Submitted to: Meeting Abstract
Publication Type: Abstract Only Publication Acceptance Date: 6/12/1997 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Changes in surface soil structure and stability during winter can result in a highly erodible soil condition. The soil erodibility factor (K) used in the Revised Universal Soil Loss Equation (RUSLE) has been adjusted to account for seasonal changes such as freezing and thawing, soil moisture, and soil consolidation. Soil aggregates can degrade to smaller aggregates by the combination of freezing and thawing and freeze drying, making the soil surface more susceptible to wind erosion. A study was conducted on a Barnes loam (fine-loamy, mixed Udic Haploboroll) near Morris, Minnesota, over three winter seasons to measure the changes in aggregate size distribution that occurred with three tillage and three crop rotations. Tillage systems were 1) fall moldboard plow, 2) fall chisel plow, and 3) ridge till. Crop rotations were 1) continuous fallow, 2) continuous corn, and 3) corn-soybean rotation. Both corn and soybean in the corn-soybean rotation were present each year. Soil samples were collected from the surface 3 cm after fall tillage (late-October) and again prior to spring tillage (mid-April). Aggregate size distribution was determined by dry sieving with a rotary sieve. Aggregates were separated into eight size classes ranging in size from <0.5 to >12 mm. Results obtained indicate that overwinter processes can have a major effect on aggregate size distribution, but the magnitude and direction of change are influenced by soil moisture levels during the final freeze/thaw cycles. Degradation of soil aggregates by freeze drying was observed along exposed clod faces throughout the winter seasons which resulted in an undetermined amount of soil movement. |
