How do you distinguish between the process of soil formation and soil-forming factors? What is the role of climate and biological activity as two important control factors in the formation of soils?
The process of soil formation or pedogenesis refers to the actual sequence of actions that transform parent material into soil. It begins with weathering creating a weathering mantle, followed by colonization by bacteria and inferior plants like mosses and lichens, accumulation of humus from dead remains, and gradual development of vegetation leading to a mature soil.
Soil-forming factors are the controlling elements that influence soil development. There are five basic factors: parent material, topography, climate, biological activity, and time. These factors act in union and affect each other's action. The process is the action, while factors are the controllers.
Climate is an important active factor in soil formation. The climatic elements include moisture (intensity, frequency, duration of precipitation, evaporation, and humidity) and temperature (seasonal and diurnal variations).
Biological activity involves colonization by bacteria and plants like mosses and lichens. Dead remains contribute to humus accumulation. Plant roots penetrate down, burrowing animals bring up particles, making the material porous with capacity to retain water and permit air passage. Biological activity is slowed or stopped if the soil becomes too cold or too dry.
Explanation
The textbook clearly distinguishes between process (pedogenesis - the actual sequence of weathering, colonization, humus accumulation) and factors (the five controlling elements). Climate is explicitly stated as an 'active factor' with moisture and temperature as key elements. Biological activity is described throughout the process section, showing how organisms contribute to soil development through humus formation and structural changes.