Abstract
In tropical acid soils, acidity is an important constraint for availability and uptake of nutrients by annual crops, and this leads to lower crop yields. Factors that contribute to low nutrient uptake efficiencies in these soils are low natural levels of most essential plant nutrients and unfavorable soil and plant environments. High P fixation capacity, Al, Mn and H toxicity, low activities of bene-ficial microorganisms, soil compaction, infestation of weeds, diseases and insects, drought and intensive monoculture are some of the major factors that contribute to the unfavorable soil and plant environments. Improving nutrient use efficiency in these soils demand adoption of special management practices. These practices include timely application of adequate levels of lime, gypsum and fertilizers to meet crop demand, use of proper crop rotation, improvement of organic matter content, control of soil erosion and use of acid tolerant crop species and cultivars within species.