Most soils in sub-Saharan Africa are acidic and have low contents of calcium (Ca2+), magnesium (Mg2+) and molybdenum (Mo). Higher concentrations and contents of hydrogen ion (H+), aluminium (Al3+) and manganese (Mn2+) found in these acidic soils are known to be the major causes of poor plant growth due to their toxicity effects to plants and micro organisms such as N-fixing bacteria. Molybdenum is also a component of some bacterial nitrogenase and therefore, is especially important for plants that live in symbiosis with nitrogen-fixing bacteria such as Rhizobium. Calcium, magnesium and molybdenum deficient plants exhibit poor growth. The most common management practice to ameliorate these acidic soil problems is through the surface application of lime or molybdenum and/ or
seed pelleting. The potential role(s) of lime and Mo in legumes with respect to growth, assimilation of metabolites, N-fixation and growth is given special attention in this review.