The role of tillage in soil redistribution on hillslopes

TLDR

Soil tillage is generally viewed as indirectly affecting erosion, yet experimental evidence indicates its redistribution can be described by a diffusion‐type equation characterized by a single diffusion constant. Field experiments reveal that tillage causes substantial downslope soil movement, with diffusion constants between 100 and 400 kg m⁻¹ a⁻¹, implying that tillage‐related erosion can exceed water erosion on many western European hillslopes, so tillage should be regarded as a primary soil degradation process.

Abstract

Summary Soil tillage is usually considered as a process having only an indirect influence on soil erosion. This paper describes the results of field experiments carried out with a mouldboard and a chisel plough showing that an important net downslope soil movement can be associated with soil tillage. Available experimental evidence suggests that the soil redistribution by tillage can be described by a diffusion‐type equation, which allows the intensity of the process to be characterized by a single number, which may be called the diffusion constant. The experimentally determined values of the diffusion constant vary between 100 and 400 kg m −1 a −1 . This implies that erosion and sedimentation rates associated with tillage may be more important than those associated with water erosion on much of the hilly arable land in western Europe. A comparison of recent hillslope evolution with model simulation results corroborates this conclusion. Therefore, tillage should be considered as a soil degradation process per se , rather than a process which makes the soil more sensitive to erosion.