AP BIOLOGY

Detailed explanation-1: -The thick brown or black substance that remains after most of the organic litter has decomposed is called humus. Earthworms often help mix humus with minerals in the soil. Humus contains many useful nutrients for healthy soil.

Detailed explanation-2: -The very dead is what we call soil humus. Soil aggregation as well as the cation exchange capacity is dependent on the amount of humus found in the soil. This pool does not decompose quickly and is labeled as stable soil organic matter.

Detailed explanation-3: -In classical soil science, humus is the dark organic matter in soil that is formed by the decomposition of plant and animal matter. It is a kind of soil organic matter. It is rich in nutrients and retains moisture in the soil. Humus is the Latin word for “earth” or “ground".

Detailed explanation-4: -Dead plants and animals are degraded in soil by decomposing bacteria and fungi. The material formed after this decomposition activity is called humus. It is very rich in nutrients and black in color. Greater the amount of humus more is the soil productivity.

Detailed explanation-5: -Organic material is anything that was alive and is now in or on the soil. For it to become organic matter, it must be decomposed into humus. Humus is organic material that has been converted by microorganisms to a resistant state of decomposition.