A meta-analysis of the effects of land management practices and land uses on soil loss in Ethiopia

Abstract

Over the last three decades, land management practices have been extensively implemented in Ethiopia. Different attempts have been made to assess the effects of land management practices on soil loss at plot scales under a range of climatic and land use conditions. However, the plot-level studies were mostly focused on limited sites and were inadequate to show the effects of land management and land cover practices across a range of practices and under various environmental contexts. A meta-analysis of 82 plot-level experiments in 59 sites was conducted to assessing the effects of land management practices and land use/cover types on soil loss relative to control practice. Random effects were accounted for the association of soil loss and environmental factors including mean annual rainfall, soil texture, and slope length. The results showed that there were significant mean soil loss differences among the categories of land management and land cover practices (p < 0.049). A large amount of residual heterogeneity (I2 = 92%) suggests that the groups of practices are heterogeneous. Mechanical erosion control and agronomic practices with the largest number of studies and somewhat area closure showed large heterogeneity across experiments.The overall mean soil loss ratio of mechanical (0.086, R2 = 81%), agronomic (0.21, R2 = 85%), and area closure (0.09, R2 = 52%) practices were significant to reduce soil loss. There was no residual heterogeneity exhibited across studies for the rest of four groups of practices. The mean soil loss ratio of mechanical practices under non-cropland, annual cropland cover, drainage, and non-cropland cover types were 0.12, 0.14, 0.27, and 0.29, respectively. Yet, with a certain level of inconsistency, the overall effects of all groups of land management and land cover practices were positive. In general, the sensitivity of environmental factors and their magnitude of association with soil loss ratio could imply that the effects of the range of land management practices and land cover types on soil loss are very contextual.