Investigation of soil translocation caused by tillage

1. Objectives Objectives of this study were to investigate the impact of tillage on soil translocation and long-term effects on soil redistribution along a hillslope. 2. Materials and Methods The experiments were conducted in spring and fall of 1999, 2000 and 2001 on fields of the agricultural school in Pyhra, Lower Austria. Mean slopes ranged between 5 and 20 %. Soil translocation was determined by means of tracers. Along the hillslope several transects were investigated using aluminum cubes as tracers inserted over the whole tillage depth. Their location was recorded using an automatic theodolite and a microprism. Tillage up- and downslope as well as along contour line were investigated. Two tillage implements were used: moldboard plough: tillage depth 0.18 - 0.23 m, speed 4.5 km h-1 , chisel plough: tillage depth 0.13 - 0.18 m, speed 8.0 km h-1 . Immediately after tillage operation the exact location of each tracer was recorded and displacement of tracers was calculated. 3. Results Overall 92 experiments were carried out during the 3-year period. Mean soil displacement due to moldboard ploughing was 0.325 m downslope and 0.133 m upslope. Chisel ploughing resulted in mean downslope movement of 0.238 m and mean upslope movement of 0.137 m. These tillages led to a net downslope soil movement of appr. 56 kg per meter tillage width for moldboard and 22 kg per m chisel ploughing. At contour tillage the upward translocation was 0.453 m with moldboard plough (turning soil upwards) respectively 0.513 m turning soil downwards and with chisel plough it was 0.051 m downwards. Soil translocations of each profile, slope gradient, tillage depth and bulk density were used to calculate implement specific values (k-values) which define the erosive capability of a tillage implement for one specific region. Moldboard ploughing as well as chisel ploughing in contour direction delivered k - values of the same order of magnitude like up/downslope tillage. Moldboard ploughing caused 2,6 times higher soil translocation than chisel ploughing. The study shows that besides water erosion soil translocation by tillage leads to downslope soil dislocation. In a long-term scale this process affects soil quality and fertility especially in upslope positions.