| Abstract
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Agroforestry parklands are agroforestry systems where trees are mixed with crops on the same unit of land. These tree-crop associations can have a positive, a negative or no effect on the soil or on the growth and yield of the plants. Foliar biomass production of the tree, Cordyla pinnata, was estimated to be 337 kg ha in a parkland located in the southern part of the peanut basin of Senegal. Effects of crown volume, orientation, distance from the trunk and pruning intensity of C. pinnata on soil physical and chemical properties, nutrient contents, and millet and peanut growth and yield were studied. Cordyla pinnata was not associated with any differences in soil physical properties (texture, bulk density or humidity). Soil organic C, total N, extractible P, exchangeable Ca and CEC were respectively 57%, 61%, 47%, 22%, and 15% higher under the canopy than in the open. For all pruning intensities combined, millet grain biomass (18%) and total millet biomass (0.5%) decreased significantly under C. pinnata. The biomass of peanut pods was also reduced (25%) under the canopy compared to the open. Under the control (non-pruned trees), total biomass of peanut plants increased with distance (1486, 2084, and 2110 g m) while under completely pruned trees, total biomass of peanut plants decreased with distance (2177, 1829, and 1787 g m). Millet and peanut yields and nutrient contents were studied using two bioassays in a nursery: (1) soils sampled at different distances from Cordyla pinnata and (2) soils mixed with different quantities of C. pinnata litter (0, 39, 78, and 156 kg of litter / t of soil). Millet and peanut plants grown on soils sampled under C. pinnata had a higher yield than those grown on soils sampled away from the canopy. Total biomass of peanut plants were reduced by litter additions (11%, 13%, and 29% respectively with 39, 78, and 78 kg of litter / t of soil) compared to the control. Total biomass of millet was increased 17, 1.9 and 1.5 times by the same treatments. K content in peanut leaves also increased with litter additions but N, P, and Ca in millet grains varied greatly. The interception of precipitation by Cordyla pinnata was studied in relationship to (1) tree crown volume, (2) distance from the tree and (3) relative light intensity. Under full canopy, 22% of gross precipitation was intercepted. There was a positive asymptotic relationship between gross precipitation and interception. The canopy storage capacity of Cordyla pinnata was 5 mm.
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