Redistribution of soil particles by the force applied by tillage is a major factor in soil degradation of
agricultural land. Decreasing tillage intensity can reduce the amount of soil displaced and the distance
moved and hence may reduce rates of erosion. To understand the relative importance of erosion, we
tabulated machine, soil and landform properties likely to be involved. We compared soil displacement
and tillage erosion rates under different systems, including mouldboard ploughing (conventional
tillage), chisel ploughing (reduced tillage), stubble cultivator (minimum tillage) and no-tillage under
dryland agriculture in northwestern Iran. The area was undulating and so all tillage took place along
contours. Metallic tracers were buried in the soil at known locations and depths and their recovery
after tillage provided a measure of soil displacement and tillage erosion. Conventional tillage along a
contour line caused significantly greater soil displacement (≃57 cm) in the direction of tillage than
reduced and minimum tillage systems (~20 and ~15 cm, respectively). Conventional tillage also caused
more lateral soil displacement (downwards in the main direction of slope, the tillage erosion rate)
than reduced or minimum tillage systems (48 cm or 152 kg/m vs. 5 and 4 cm or 16 and 7 kg/m,
respectively). Although a range of factors contribute to the tillage systems used by farmers, our results
suggest that under dryland conditions, similar to those found in our study area, adoption of
noninversion, reduced tillage along the contour, for example by chisel ploughing can substantially
limit tillage erosion relative to conventional tillage.