BULK DENSITY AND SOIL RESISTANCE VARIABILITY IN DIFFERENT SOIL MOISTURE CONDITIONS UNDER DIFFERENT TILLAGE SYSTEMS

Field experiment with 6 soil tillage systems was set up on Stagnosol in Central Croatia in 1994. Tillage systems differed in tools that were used, depth and direction of tillage. 13 years after experiment establishment, oil seed rape was cover crop (season 2006/07). In 2007 soil resistance, bulk density and soil water content data were collected in order to detect effects of different soil tillage systems on soil compaction. Data were obtained at 4 depths in different time intervals during vegetation period. Statistical data evaluation showed significant differences in soil resistance between all tillage systems at all depths. Soil resistance varied at depth 0-10 cm from 0.46 to 2.82 MPa, at depth 10-20 cm from 0.85 to 3.85 MPa, at depth 20-30 cm from 1.02 to 5.01 and at depth 30-40 cm from 1.21 to 5.31 MPa. Bulk density values at all depths of all tillage systems varied from 1.46 to 1.73 g cm(-3). Soil water content during research period varied from 27 to 43%. It can be concluded that climate conditions differently affected soil resistance at different tillage practice.