Improving nutrient use efficiency of annual crops in Brazilian acid soils for sustainable crop production

In tropical acid soils, acidity is an important constraint for availability and uptake of nutrients by annual crops, and this leads to lower crop yiel ds. Factors that contribute to low nutrient uptake efficiencies in these so ils are low natural levels of most essential plant nutrients and unfavorabl e soil and plant environments. High P fixation capacity, Al, Mn and H toxic ity, low activities of beneficial microorganisms, soil compaction, infestat ion of weeds, diseases and insects, drought and intensive monoculture are s ome of the major factors that contribute to the unfavorable soil and plant environments. Improving nutrient use efficiency in these soils demand adopt ion of special management practices. These practices include timely applica tion of adequate levels of lime, gypsum and fertilizers to meet crop demand , use of proper crop rotation, improvement of organic matter content, contr ol of soil erosion and use of acid tolerant crop species and cultivars with in species.