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Haregeweyn, N., Poesen, J., Deckers, J., Nyssen, J., Haile, M., Govers, G., Verstraeten, G. & Moeyersons, J. 2007. ‘Sediment-bound nutrient export from micro-dam catchments in Northern Ethiopia’. Land Degradation & Development. (PR).
Article in a scientific Journal / Article in a Journal
The losses in soil nutrients (nitrogen (N), available phosphorus (Pav), organic carbon (OC), potassium (K), calcium (Ca)
and magnesium (Mg)) in the catchment and the storage in the reservoir as a result of sediment delivery were assessed in
13 catchments/reservoirs in Tigray, Northern Ethiopia. This specifically dealt with factors controlling the losses, the fertility
status of the deposited sediment, the nutrient export (NE) rates and associated costs.
Enrichment ratio (ER) values >1 were observed for the plant nutrients and the finer soil fractions. The high ER is associated
with the preferential transport of nutrients bound to finer soil fractions and the parent material dissolution and its transport via
runoff. However, the fertility status of the deposited sediment is not sufficient by itself to support a sustainable crop growth and
hence external addition is necessary, mainly for N and Pav fertilizer.
Generally, rates of NE were high. The high OC export on the other hand dictates the potential of reservoir sediments for OC
sequestration. The cost price of loss of only N and Pav, eroded from the catchment slopes, was estimated at s342million (Euros)
in March 2006 for the Tigray. Pity enough, policy makers and beneficiaries do not realize the magnitude of the problem, which
forms a major threat for the crop production in the country. Therefore, it is important not only to make the public aware of the
problem but also of implementing integrated soil fertility management practices. Copyright # 2007 John Wiley & Sons, Ltd.