Soil fertility and arbuscular mycorrhizal fungi related to trees growing on smallholder farms in Senegal

• Published in: Journal of arid environments 2008-07, Vol.72 (7), p.1247-1256
• Main Authors: Bernatchez, F., Jeannotte, R., Begg, C.B.M., Hamel, C., Whalen, J.K.
• Format: Article
• Language: English
• Subjects: agroecosystems; Agroforestry; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Cenchrus americanus; Dryland farming systems; equations; Faidherbia albida; Fundamental and applied biological sciences. Psychology; Glomalin; grain crops; millets; mycorrhizal fungi; nitrogen; nitrogen fixation; nutrient availability; Pennisetum glaucum; phosphorus; potassium; rural areas; Senegal; small-scale farming; soil fertility; soil organic carbon; Soil organic matter; soil pH; spatial variation; Synecology; Terrestrial ecosystems; vesicular arbuscular mycorrhizae; West Africa
• ISSN: 0140-1963; 1095-922X
• DOI: 10.1016/j.jaridenv.2007.12.014

Tree cultivation in the dryland agroecosystems is increasingly advocated as a strategy to protect and reverse soil fertility decline, thus sustaining agricultural production. Woody legumes trees like the Ana tree Faidherbia albida (Del.) Chev. host N 2-fixing bacteria as well as arbuscular mycorrhizal fungi (AMF), which may contribute to the soil organic carbon pool and soil fertility. The objective of this work was to determine how trees influenced AMF and soil fertility in the agroecosystems of two rural communities (Palmarin and Fimela) of the Saloum Agricultural Eco-Region of Senegal. Smallholder farmers typically cultivated 3–4 fields ranging in size from 0.5 to 2.0 ha with the major crop being millet ( Pennisetum glaucum L.). Soil fertility was low to medium, with about 1% soil organic matter (SOM), 17±2.2 mg Bray-1 P kg −1 and 65±5.8 mg extractable K kg −1 in the fields studied. There were seven times more trees per hectare and greater tree diversity in fields around Palmarin, where the smallholder farmers resided, than in the fields they cultivated in Fimela. Social norms appeared to protect trees inside the residential village, while trees farther away are prone to being cut. The relationships between trees, AMF and soil fertility were examined using exploratory path analysis, a structural equation modeling technique. The path analysis model revealed a direct and significant ( P