What kind of soil type is found thickest, globally, in land near the Missouri River in Iowa, USA, at the edges of the Gobi Desert and beside the Yellow River in China?
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?
