Experimental research revealed that mulching the soil surface is an effective soil conservation practice. However,
reported effectiveness ofmulch covers varies widely and there are indications that spatialmeasurement scale (i.e.
plot length) explains part of this variability. The objective of this study is therefore to analyse the impacts of plot
length at which field and laboratory experiments were conducted on the effectiveness of mulch covers in
reducing soil loss by water erosion. In this review, 41 studies investigating the impacts of mulch cover on soil
erosion bywater are analysed (plot length ranges between 0.1 and 30.5m). Calculatedmulch effectiveness factors,
i.e. b-values from the mulch factor equation, range between 0.0097 and 0.1320 and increase linearly with plot
length for the reviewed experiments: b=0.022+0.0017*plot_length (m); R2=0.37; n=41. However, care should
be takenwhen using this relationship for extrapolations to longer plots. Furthermore, slope gradient, soil type and
mulch type determine the variability of the effectiveness of mulch covers in reducing soil erosion rates by water.
Depending on the dominant soil erosion process (i.e. splash, interrill, rill and interrill or rill erosion), these
variables also partly control the effectiveness of a mulch cover in reducing soil erosion by water.