Dossa E. L. auteur aut IRD Diedhiou S. auteur aut IRD Compton J. E. auteur aut IRD Assigbetsé Komi auteur aut IRD Dick R. P. auteur aut IRD text journalArticle eng text/pdf born digital access Two shrub species (Piliostigma reticulatum (D.C.) Hochst (Caesalpinioideae) and Guiera senegalensis J.F. Gmel (Combretaceae) are commonly found in farmers' fields at varying densities in semi-arid Senegal and throughout the Sahel where soils have chronically low phosphorus (P) availability. It seems plausible that shrub litter and the rhizospheres could influence P fractions and other chemical soil properties that affect crop productivity. Thus, a study was done at two sites, on the distribution of inorganic and organic soil P pools, organic C levels, and pH in soil beneath and outside the canopies of P. reticulatum and G. senegalensis (0-30 cm depth). Both sites had low total P ranging from 64 mg P kg(-1) to 135 mg P kg(-1), and low extractable PO4 (resin Pi) (1-6 mg P kg(-1)) with P fractions dominated by NaOH-P. Organic P (Po) made up about 50% of total P, and most of the organic P (> 60%) was found in the NaOH-P fractions. The labile P, particularly bicarb-Po was higher in soil beneath shrub canopies (8.4 mg P kg (-1)), than outside the canopy (6.2 mg P kg (-1)). Similarly, C, N and P to a lesser extent, were more concentrated beneath shrub canopies. P. reticulatum soil was dominated by the NaOH-Po fraction, whereas G. senegalensis had higher bicarb-Po at one of the study sites. An index of biologically available organic P (Bicarb-Po) / (Bicarb-Po + Bicar-Pi + Resin Pi) was > 60% and indicates that biological processes represent an important part of P cycling in these shrub ecosystems. The differential ability of shrubs in modifying soil chemical properties under their canopies has major implications for biogeochemical cycling of nutrients and C in sandy soils of semi arid Sahelian ecosystems. specialized Canopy soil P fractions Sahel Semi-arid Shrubs Total C 068 327 1-2 185-198 2010 0032-079X https://www.documentation.ird.fr/hor/fdi:010049227 10.1007/s11104-009-0044-8 0032-079X [F B010049227] https://www.documentation.ird.fr/hor/fdi:010049227 https://www.documentation.ird.fr/intranet/publi/2010/02/010049227.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2010-03-10 2022-09-09 fdi:010049227 fre