OBJECTIVE FORESTRY

Detailed explanation-1: -Humus is dark, organic material that forms in soil when plant and animal matter decays.

Detailed explanation-2: -Soil colour is usually due to 3 main pigments: black-from organic matter. red-from iron and aluminium oxides. white-from silicates and salt.

Detailed explanation-3: -Hence, Humus is dark-colored partially decayed organic matter rich in nutrients. It makes the soil porous thereby, increasing its air and water holding capacity.

Detailed explanation-4: -Clay particles have a very tiny particle size and are compact thereby providing dark color to the soil.

Detailed explanation-5: -The uppermost horizon is called the “organic” horizon or “O” horizon. It consists of detritus, leaf litter and other organic material lying on the surface of the soil. This layer is dark because of the decomposition that is occurring. The organic materials in this layer decompose into nutrients that enrich the soils.