loamy : peaty
Peaty soils is a very understandable and widely used term, which would also well describe soils common in tropical areas, both swamp and rain forest. Peaty soils are soils that have high acidity and high organic content usually because they are saturated and poorly drained.
Ramona mentioned the term 'loose earth' however outside of the garden center peaty soils tend to be compacted, spongy is the most common term to describe the texture of peaty soils in English.
This may not be the characteristic of peaty soils in Malaysia, but there is the possibility of confusion by a reader with a temperate zone POV. Anyone who has ever been hit over the head with a peat sod or briquette could not imagine peat as being loose. This is why I am mentioning loamy soils.
In a gardeners classification of soils peaty soils are most closely related to loamy soils. Loamy soils are also high in organic material but, better drained and lower in acidity. They are crumbly in texture.
To a gardener and farmer you have :
sand, chalk, loamy, peaty, silt, clay -soils
There is another classification system used by people who care less about soil productivity and more about structure. Civil engineers and
Architects may use this classification :
sand, sandy-loam, loam, loamy-clay, clay
In this category peaty soils fall in the category as loam.
Engineers are more concerned with compaction, and they will modify the landscape so that structures are placed over clay and sandy soils to prevent settling. peaty soils will be excavated and drained. So the distinction between peaty and loamy is not very important in this classification
Native speaker of: English