Fertile soil contains a store of nutrients in adequate proportions for the healthy growth of plants. Such a soil must also possess physical features that make the nutrients available, e. g. Good drainage and aeration.

A number of factors reduce the amount of nutrients (fertility) in the soil.

These factors include

(a) Monoculture/monocropping

• This is when a farmer grows a particular species of plant e. g. corn, on a particular piece of land for several years.
• Monocropping leads to depletion of a particular mineral *om the soil, since different plant species use different minerals from the soil.

(b) Over cropping

• This occurs when a piece of land is used continuously to grow crops and never left to fallow for natural vegetation to grow there again.
• Fallowing gives the soil time to rest, and to rebuild its nutrient and organic matter level.
• Since crops remove many nutrients and are then eaten by humans, these nutrients are not returned to the soil.

(c) Overgrazing

• Overgrazing occurs when plants are exposed to grazing for too long, such as when grazing animals are confined to graze on a particular area e. g. Ranch for a long period.
• Overgrazing results in depletion of vegetation and exposure of the soil.
• In addition, the feet/hooves of the cattle trample and compact/compress soil into a hard layer, preventing easy drainage.

     Soil Erosion

What is soil erosion?

            Soil erosion is the wearing away and removal of fertile top soil from an area by wind and water (during a heavy rainfall), at a greater rate than it is formed.

• Erosion removes the topsoil first. Once this nutrient-rich layer is gone, few plants will grow in the soil again.

• Plants cannot grow on eroded land. Erosion is, therefore, a serious problem as it affects the economy of a country that depends on agriculture for supplying its needs.