Impact of short-term ploughless tillage on soil physical properties, winter oilseed rape seedbed formation and productivity parameters

The demonstrational short-term on-farm field experiment was carried out on silty loam soil at the agricultural farm "Gruduva" (Sakiai reg., Lithuania) in 2003-2004. The aim of investigations was to evaluate impact of ploughless soil tillage on some soil physical properties, winter oilseed rape seedbed formation and productivity parameters. Two different soil tillage systems, conventional (CT) (deep (22-24 cm) mouldboard ploughing, presowing soil levellering and soil rolling after sowing) and reduced (RT) (disc harrowing, presowing soil rolling), were investigated. In RT conditions winter oilseed rape seedbed was formed shallowly (33.2 mm in comparison with 37.2 mm in CT), had significantly higher (20%) moisture content in seed incorporation zone (L2 layer) and better composition of soil aggregates (27% higher amount of <2 mm soil aggregates in L2 layer) than in CT. These seedbed conditions positively influenced on winter oilseed rape stand density at the beginning of vegetation. Deep ploughing (CT) of soil in autumn fiddly crushed arable layer and made extremely high amount of micro-structure up to 28%. That significantly decreased amount of water-stable soil aggregates. In RT stubble incorporation into the shallow layers of soil prevented rapid moisture evaporation in dry weather conditions in spring and suppressed water runoff and distribution on soil surface in wet conditions before harvesting. Ploughless soil tillage mostly had positive significant influence on winter oilseed rape productivity parameters. Winter oilseed rape plants grew about 67 boughs and up to 4 thousand pods per m(2) more in comparison with CT, that influenced on higher (41%) biological yield of seeds.