Soil acidity, pH and aluminum management in tropical soils: the Brazilian experience

摘要

Soybean is grown in Brazil from Parallel 33 deg S to the Equator, under climates ranging from temperate to equatorial. Climate and geology diversity of these regions led to formation of very different soils. Within the diversity, practically all of the soils are acidic but the main limiting factor is different in each region. In the South, besides Al toxicity, Mn toxicity is very important as a consequence of low pH. On the other side, in most of the Cerrado region, Mn deficiency, and not toxicity,is a problem, but Al toxicity is important, as well as the low Ca and Mg contents. No-tillage has become very popular in Brazil and soybean is the main crop under no-till throughout the Country. Where soybean is not under no-till, several degrees of conservation tillage are employed, always leaving some crop residues over the soil surface. This practice has an important impact on soil acidity management.