Science et changements planétaires / Sécheresse


Impact of quickset hedges on soil water management and crop yields in a catchement basin in Thyssé-Kaymor, Senegal Volume 12, issue 1, Mars 2001


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ISRA/CRA, BP 53, Bambey, Sénégal
  • Page(s) : 15-24
  • Published in: 2001

Overuse of vegetation on the Keur Dianko plateau (13°45 N ; 15°40 W) and reduction of fallowing time have weakened the ferruginous crust soils inthis area and given rise to runoff phenomena. Isohypse quickset hedges help balance Sahelian ecosystem and reduce runoff and erosion of arable land. Their effects on groundwater management and crop yields were studied on the Keur Dianko basin glacis. Four years after planting these quickset hedges, the effects of 12 hedgerows formed with 11 different species (Acacia nilotica var. adansonii, A. senegal, A. seyal, A. mellifera, Bauhinia rufescens, Dichrostachys glomerata, Piliostigma reticulatum, Ziziphus mauritiana, Gliricidia sepium, Parkinsonia aculeata, Prosopis chilensis) were assessed and gavbe the following results: humidity and deep leaching were highest 0.5-1 m from the hedgerows than from 2 to 5 m; better water infiltration upstream than downstream from the hedges; marked difference in water reserves according to seasons and distance from the hedgerows (from 0,5 to 1 m, water storage was greater downstream than upstream, with an 80 mm difference between rainy season and dry season levels in the same soil horizon). These soil moisture profile and water storage improvements near hedgerows were strangely enough accompanied by crop yield losses (greater in millet than groundnut). This trend migh be explained by tree root competition with crops of hedge root toxicity.