OBJECTIVE FORESTRY

Detailed explanation-1: -Organic matter makes up just 2–10% of most soil’s mass and has an important role in the physical, chemical and biological function of agricultural soils.

Detailed explanation-2: -The basic components of soil are minerals, organic matter, water and air. The typical soil consists of approximately 45% mineral, 5% organic matter, 20-30% water, and 20-30% air.

Detailed explanation-3: -organic matter content of the soil. Most soil organic matter originates from plant tissue. Plant residues contain 60-90 percent moisture. The remaining dry matter consists of carbon (C), oxygen, hydrogen (H) and small amounts of sulphur (S), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg).

Detailed explanation-4: -The topsoil has the highest concentration of organic matter, nutrients and is where most of the soil’s biological activity occurs. Soil that is not protected by residue or living cover is subject to erosion.

Detailed explanation-5: -The living portion represents about 5 percent of the total soil organic matter. Micro-organisms, earthworms and insects help break down crop residues and manures by ingesting them and mixing them with the minerals in the soil, and in the process recycling energy and plant nutrients.