Theory question 205
Soils(a) Define the term soil. (b) Outline three functions of soil. (c) Highlight any two negative effects of man's activities on soil. (d) Describe any two methods of conserving soil.
Show the model answer
(a) Soil is the thin loose upper layer of the earth's surface made of weathered rock particles, humus, water, air and living organisms, in which plants grow.
(b) Supports plant growth (anchorage, nutrients, water); habitat for organisms; raw material (clay for pottery, bricks); foundation for buildings and roads; filters and stores water; recycles dead matter.
(c) Bush burning destroys humus and organisms; deforestation and overgrazing expose soil to erosion; overuse/monocropping exhausts nutrients; pollution by chemicals, oil spills and waste; mining and construction remove topsoil.
(d) Contour ploughing/terracing to slow runoff; afforestation and windbreaks; cover cropping and mulching; crop rotation and fallowing; use of manure and fertilizer; controlled grazing.
Describe how each conservation method works.