Wa. Payne et al., Crop diversification in the Sahel through use of environmental changes near Faidherbia albida (Del) A Chev, CROP SCI, 38(6), 1998, pp. 1585-1591
Pearl miller [Pennisetum glaucum (L.) R. Br.] is well adapted to the harsh
environment of the West African Sahel but has relatively low genetic yield
potential and market value. Crop diversification is desirable, but alternat
ive crops generally cannot tolerate the harsh climate and soil conditions t
hat pearl miller can. This study tested the hypothesis that alternative cro
ps could be grown near Faidherbia albida (Del.) A. Chev. (syn. Acacia albid
a), a tree species of semiarid Africa, because of its ameliorating effects
on the surrounding environment. Octants around trees were sown to pearl mil
let, maize (Zea mays L.), sorghum [Sorghum bicolor (L.) Moench], and cotton
(Gossypium hirsutum L). Crop, soil, and climate measurements were made per
iodically during the growing season. Soil fertility and fine-particle conte
nt decreased with distance from trees. Inside the canopy, irradiance was re
duced by 0.5 to 1.0 kW m(-2) and daytime soil temperature at a depth of 0.0
5 m was reduced by as much as 6 degrees C. Improved conditions within the t
ree canopy were reflected by increased crop yield. Sorghum and maize tended
to use less soil water than millet. Sorghum and maize yielded more than 12
0 g m(-2) near the tree bole, whereas millet yielded approximate to 80 g m(
-2). Near the edge of the tree canopy, where pearl millet maintained yields
of 40 g m(-2), the other crops tended to fail. Faidherbia albida trees can
be used to diversify cropping systems and increase yields in the Sahel, bu
t adoption of this agroforestry system may be constrained by modern social
factors which have disrupted traditional land husbandry practices.