tailieunhanh - Grasslands

The soils of the South American llanos and cerrado grasslands are predominantly old soils from which most of the plant nutrients have been lost. In many places there are layers of laterite (see the sidebar), which give them a red or yellow color. African savanna soils are much younger and more fertile. These shade into arid soils in the north and into wetter soils on high ground. On the southern side there are poor, exhausted, lateritic soils typical of tropical rain forest. The soils of temperate grasslands—the prairie, steppe, pampa, and veld—are deep and fertile, making them ideal agricultural soils. | Simpo PDF Merge and Split Unregistered Version - http Simpo PDF Merge and Split Unregistered Version - http 40 GRASSLANDS Simpo PDF Merge and Split Unregistered Version - http The soils of the South American llanos and cerrado grasslands are predominantly old soils from which most of the plant nutrients have been lost. In many places there are layers of laterite see the sidebar which give them a red or yellow color. African savanna soils are much younger and more fertile. These shade into arid soils in the north and into wetter soils on high ground. On the southern side there are poor exhausted lateritic soils typical of tropical rain forest. The soils of temperate grasslands the prairie steppe pampa and veld are deep and fertile making them ideal agricultural soils in places where the climate is suitable for farming. Laterite Tropical soils are often red or yellow as a result of the presence of oxides and hydroxides chiefly of iron and aluminum. These compounds sometimes form hard lumps or continuous layers of a rock called laterite. The name is from later the Latin word for brick. Most laterite is porous and claylike in texture. The surface is dark brown or red but if the laterite is broken the interior is a lighter red yellow or brown. Laterite is fairly soft while it remains in the soil but it hardens when it is exposed to air. It has been mined as a source of iron and nickel. Bauxite the most important aluminum ore is very similar to laterite. In some lateritic soils aluminum combines with silica to form the mineral kaolinite also known as China clay which is used in the manufacture of fine porcelain and as a whitening agent or filler in paper paints medicines and many other products. Laterite forms in well-drained soils under humid tropical conditions. The high temperature and abundant moisture accelerate the chemical reactions that break down rock the process called chemical weathering and many of the .