OBJECTIVE FORESTRY

Detailed explanation-1: -The A horizon is the top layer of the mineral soil horizons, often referred to as ‘topsoil’. This layer contains dark decomposed organic matter, which is called “humus". The technical definition of an A horizon may vary between the systems, but it is most commonly described in terms relative to deeper layers.

Detailed explanation-2: -The O horizon is typically at the top of the soil structure and is made up of mostly organic matter. This organic matter is vital to the growth of crops and other plants because it holds nutrients such as carbon, phosphorus, nitrogen and sulfur.

Detailed explanation-3: -Greater than 20-30% organic matter (less if high clay content).

Detailed explanation-4: -The O-Horizon The O horizon is the upper layer of the topsoil which is mainly composed of organic materials such as dried leaves, grasses, dead leaves, small rocks, twigs, surface organisms, fallen trees, and other decomposed organic matter.

Detailed explanation-5: -The B horizon lies underneath the A horizon and is commonly called the subsoil. It is the horizon of maximum accumulation, or illuviation, of clay, iron, aluminum, or other compounds leached from the A horizon. In some soils the B horizon forms through alteration of material in place rather than by illuviation.