OBJECTIVE FORESTRY

Detailed explanation-1: -Diffusion: Most of the gaseous interchange in soils occurs by diffusion. Atmospheric and soil air contains a number of gases such as nitrogen, oxygen, carbon dioxide etc., each of which exerts its own partial pressure in proportion to its concentration.

Detailed explanation-2: -This chapter focuses on the gas diffusion in soil. Oxygen is consumed and carbon dioxide is generated by the metabolic activity of microorganisms and plant roots in the soil. Oxygen, carbon dioxide and water vapor all diffuse into and out of the soil.

Detailed explanation-3: -Plants use photosynthesis to capture carbon dioxide and then release half of it into the atmosphere through respiration. Plants also release oxygen into the atmosphere through photosynthesis.

Detailed explanation-4: -Oxygen is found either dissolved in the soil solution or in the soil atmosphere, but soil oxygen concentrations in solution are much lower than in the soil atmosphere. The total amount of pore space depends on soil texture and soil structure. Soils high in clays have more total pore space, but smaller pore sizes.