DRYING STRESS EFFECT ON MECHANICAL-BEHAVIOR OF A CLAY-LOAM SOIL

The mechanical behaviour of agricultural soils has a large role in det ermining the performance of agricultural implements and the resulting soil tilth, Seasonal wetting and drying of these soils induces drying stresses that alter the soil physical state and its properties. The pe rformance of a simple vertical tine was investigated in a clay-loam so il subjected to three different levels of drying stress in a soil bin. Results showed that changes in most soil properties caused by tillage depended on drying stress. Soil bulk density decreased after tillage, although it was not significantly affected by drying stress. Soil she ar strength, tine draft and aggregate size increased significantly wit h drying stress. Dried soils subjected to high drying stress broke in a less periodic manner and into larger masses than unwetted soil. (C) 1998 Elsevier Science B.V. All rights reserved.