Deficiency of phosphorus and molybdenum as major growth limiting factors of pearl millet and groundnut on an acid sandy soil in Niger, West Africa

acid soils arachis hypogaea carence du sol deficiencias del suelo exigence des plantes fosforo growth disorders molibdeno molybdenum necesidades de las plantas niger panicum pearl millet phosphore phosphorus plant requirements sandy soils soil deficiencies sol acide sol sableux suelo arenoso trastornos del crecimiento trouble de la croissance