Soil organic carbon management for sustainable land use in Sudano-Sahelian West Africa |
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Authors: | A Bationo A Buerkert |
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Affiliation: | (1) Tropical Soil Biology and Fertility Programme, P.O. Box 30592, Nairobi, Kenya;(2) Institute of crop science, university of Kassel, Steinstr. 19, D-37213 Witzenhausen, Germany |
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Abstract: | Judged by their negative nutrient balances, low soil cover and low productivity, the predominant agro-pastoral farming systems
in the Sudano-Sahelian zone of West Africa are highly unsustainable for crop production intensification. With kaolinite as
the main clay type, the cation exchange capacity of the soils in this region, often less than 1 cmolc kg−1soil, depends heavily on the organic carbon (Corg) content. However, due to low carbon sequestration and to the microbe, termite
and temperature-induced rapid turnover rates of organic material in the present land-use systems, Corg contents of the topsoil
are very low, ranging between 1 and 8 g kg−1 in most soils. For sustainable food production, the availability of phosphorus (P) and nitrogen (N) has to be increased considerably
in combination with an improvement in soil physical properties. Therefore, the adoption of innovative management options that
help to stop or even reverse the decline in Corg typically observed after cultivating bush or rangeland is of utmost importance.
To maintain food production for a rapidly growing population, targeted applications of mineral fertilisers and the effective
recycling of organic amendments as crop residues and manure are essential. Any increase in soil cover has large effects in
reducing topsoil erosion by wind and water and favours the accumulation of wind-blown dust high in bases which in turn improves
P availability. In the future decision support systems, based on GIS, modelling and simulation should be used to combine (i)
available fertiliser response data from on-station and on-farm research, (ii) results on soil productivity restoration with
the application of mineral and organic amendments and (iii) our present understanding of the cause-effect relationships governing
the prevailing soil degradation processes. This will help to predict the effectiveness of regionally differentiated soil fertility
management approaches to maintain or even increase soil Corg levels.
This revised version was published online in June 2006 with corrections to the Cover Date. |
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Keywords: | clay content crop residues GIS millet mineral fertilisers soil erosion sustainability |
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