When it decays to the point in which it is no longer recognizable it is called soil organic matter. When the organic matter has broken down into a stable substance that resist further decomposition it is called humus.
Which of the soil types described by the Food and Agriculture Organization of the United Nations (FAO) is most common world-wide?
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?
