DUFF SOIL & MULL SOIL

PRERNA FOR IAS

DUFF SOIL  & MULL SOIL

1. Duff Soil Horizon

Duff is a partially decomposed organic layer found on the forest floor between fresh plant litter and the mineral soil beneath. It consists of leaves, needles, bark, twigs, and woody debris in different stages of decomposition. The layer is commonly divided into the Fermentation (F) layer, containing partially decomposed material, and the Humus (H) layer, containing well-decomposed organic matter. Duff is typically dark brown to black in color and has a spongy texture that retains moisture effectively. It supports fungi, bacteria, and soil organisms and is especially common in coniferous forests where decomposition occurs slowly.

2. Mull Soil Horizon

Mull is a well-humified and biologically active form of humus that is thoroughly mixed with mineral soil. Unlike duff, it does not form a separate organic layer because organic matter is rapidly decomposed and incorporated into the soil. Mull develops under conditions of high biological activity, particularly where earthworms and other soil fauna are abundant. It has a crumbly structure, excellent aeration, and high nutrient availability. Mull soils are usually neutral to slightly acidic in pH and are commonly found in deciduous and broadleaf forests. They are considered highly fertile and ideal for plant growth.

3. Layers of Duff (L–F–H Layers)

The duff horizon consists of three distinct layers. The L (Litter) layer contains fresh organic