SSS 1 Biology - Relevance of Biology to Agriculture

BEHAVIOURAL OBJECTIVES:

By the end of the lesson, students should be able to:

i. Describe and state seven(7) effects of bush burning on ecological system.
ii. Define and state five(5) effects of overgrazing.
iii. Define and state six(6) effects of fertilizers.
iv. State five(5) effects of pesticides and herbicides.
v. Define and state seven(7) effects of tillage.
vi. Define and state six(6) effects of deforestation.
vii. State five(5) effects of bush burning.

INTRODUCTION:The following agricultural practices carried out by farmers have some consequences on ecological system. These agricultural practices include: Bush burning, Overgrazing, Fertilizer application, etc.

Bush Burning

Bush burning involves the setting of fire on the bush to clear out vegetation of an area

Effects

i. It destroys organic matter in the soil.
ii. The atmosphere is polluted with smoke.
iii. Many soil micro-organisms which are beneficial are killed.
iv. It exposes the soil to erosion and leeching.
v. Leads to extinction of some species.
vi. Reduces water holding capacity of the soil.
vii. Leads to succession.

Overgrazing

Overgrazing is a situation where there are more animals feeding or grazing excessively on the vegetation of an area.

Effects

i. Removes vegetative cover of the soil.
ii.It exposes the soil to erosion.
iii.Destroys soil structure.
iv.Causes poor growth of vegetation.
v.Leads to compactness of the soil.

Fertilizer application

Fertilizers are chemicals applied on soil to improve its fertility.

Effects

i. It deteriorates the soil structure.
ii.It improves soil porosity.
iii.Supplements nutrients contents of the soil.
iv.Increases the population of microorganisms in the soil.
v.Stimulates vegetative growth, hence reduce soil erosion.
vi.Excess application of fertilizer can cause soil acidity.

Pesticides/Herbicides

Effects

i. Causes environmental pollution.
ii. Destroy useful plants and animals.
iii. Reduces the population of target insects or plants.
iv. Causes death of aquatic organisms when washed into rivers.
v. Food chain is affected.

Tillage

Tillage is defined as the digging or breaking of the soil to be loose for cultivation.

Effects

i. It encourages leaching.
ii. Loosens the soil.
iii. Exposes the soil to erosion.
iv. Aerates the soil.
v. Leads to poor vegetation growth.
vi. Exposes soil organisms and may kill some.
vii. Changes the ecology of the land.

Deforestation

Deforestation is the continuous removal of forest trees indiscriminately without replacing them.

Effects

i. Encourages soil erosion.
ii.Reduces the humus content of the soil.
iii.Reduces wildlife population in an area.
iv.Leads to desertification.
v.Results to loss of soil nutrients through leaching/erosion.
vi.Hinders micro-organisms in the soil.

Bush clearing

Effects

i. Rich top soil is removed.
ii.Increases temperature of the soil.
iii.Poor vegetation growth in an area.
iv.Exposes the soil to erosion.
v.Increase the rate of water evaporation from the soil due to direct sunshine.