Sustainable Soil Use in Tropical South America, With Emphasis On Brazil

Soils provide plants with a medium in which roots can anchor themselves and support their canopies, and from which they can tap reserves of water and nutrients. To supply adequate space, water and nutrients, a good soil should be deep, permeable, porous, with good water and nutrient retention capacity and rich in a balanced amount of minerals and organic compounds. Most soils do not have these ideal characteristics. However, in their long period of evolution, plants adapted to almost any soil condition and covered most of the earth’s surface, except for the harshest sites. Under these natural conditions, soil and plants maintain a continuous interaction where changes in the characteristics of soils and vegetation are mutually interdependent. Mineral nutrients cycle from soil to plants and back to the soil: absorbed by roots, incorporated into plant tissues, sometimes consumed by animals, then returned to the soil as litter which is decomposed by soil organisms. Soil losses by erosion are compensated by slow soil formation processes, so that a soil layer forms nearly everywhere, except steep slopes. These quasi-stable situations are considered sustainable.