Effect of crop residues on root growth and phosphorus acquisition of pearl millet in an acid sandy soil in Niger

The effect of long-term (1983–1988) applications of crop residues (millet straw, 2–4 t ha-1 yr−1) and/or mineral fertilizer (30 kg N, 13 kg P and 25 kg K ha-1 yr-1) on uptake of phosphorus (P) and other nutrients, root growth and mycorrhizal colonization of pearl millet (Pennisetum glaucum L.) was examined for two seasons (1987 and 1988) on an acid sandy soil in Niger. Treatments of the long-term field experiment were: control (−CR−F), mineral fertilizer only (−CR+F), crop residues only (+CR−F), and crop residues plus mineral fertilizer (+CR+F).