Question

About half the soils in South America are nutrient-poor sediment, soils leached of silica and containing concentrations of iron and aluminium oxides, acidic soils low in lime, or azonal soils consisting mainly of badly consolidated material known as what?

Answer 1

Regosols
Gleys are clay soils in which the substrate is generally sticky and often structureless; grumosols are soils with a high content of expanding clays; planosols are soils in which salts and minerals have been leached out of upper layers and compacted at a lower level. All of these soils are difficult for sustained good growth. Only about 10% of South American soil is deemed good growing soil.