The effect of soil erosion on crop productivity and land use change
(2004)
Files
Bakker.pdf
Restricted Access - Adobe PDF
- 37.94 MB
Details
- Authors
- Supervisors
- Abstract
- Soil erosion may affect agricultural productivity and land use changes. Quantitative estimates on the relationship between soil erosion and crop productivity, however, are made only at the plot scale and do not allow for general conclusions due to the large variability in outcomes. At the regional scale no quantitative estimates have been made on the relationship between erosion and neither productivity nor land use change. In this thesis the relationship between soil erosion and agricultural productivity is quantified at both the plot and the regional scale. Furthermore, the hypothesis is tested whether erosion induced productivity declines also invoke land use changes. Methodologies to assess the effect of erosion on crop productivity and land use are characterised by their indirectness: monitoring directly the effect of erosion on yields is impossible since erosion is generally a gradual process and because of the long time-spans involved, its effect on productivity is often obscured and confounded by other trends in yields which are mainly caused by technological innovations. Modelling techniques have been applied to assess the effect of erosion on yields, but the lack of observed effects makes it troublesome to validate these models. This thesis therefore deduced empirical relationships based on observations made at various scale levels. Empirically derived relationships involve the danger of misinterpretation of the observed association, especially when several potential explanatory variables are involved. The risk of confounding the effect of erosion on productivity and or land use change with the effects of other variables on productivity and or land use change is unavoidable. Depending on the scale studied, erosion confounds with position on slope (plot scale), with slope (catchment scale), or with climatic and economic gradients (regional scale). Erosion-induced productivity declines found in this thesis are in the order of magnitude of several percents per 0.1 m of soil loss. The relative importance of the effect of erosion on productivity depends strongly on the overall productivity and on erosion rates. In northern Europe erosion rates are low and productivity is high, so that erosion-induced productivity losses are generally negligible, whereas in southern Europe, where erosion rates are generally much higher and productivity is lower, erosion can have a serious detrimental impact on productivity. The effect ranges from 3% per 0.1 m soil lost for highly productive agro-ecosystems to 15% per 0.1 m soil lost for marginally productive agro-ecosystems. This gradient is further pronounced by the fact that erosion rates are generally low in northern Europe where the highly productive systems are situated and high in southern Europe where the marginally productive systems are situated. It is not likely that land use changes are driven by erosion, although the spatial pattern of land use changes can be determined by erosion. As erosion is a spatially variable process, it will have a considerable effect on the water availability and soil depth in some locations and not in others, causing land uses that put a high demand on soil and soil water to migrate to areas with lower erosion rates. However, this will only happen in areas where the impact of erosion on productivity is significant, i.e. where erosion rates are high, and general productivity is low.
- Affiliations
Citations
Bakker, M. (2004). The effect of soil erosion on crop productivity and land use change. https://hdl.handle.net/2078.5/124178