EFFECTS OF AGRICULTURAL ACTIVITIES ON THE ECOSYSTEM
The activities include:
1. Bush Clearing;
Exposes the soil to erosion
Leaching of mineral salts
Prolonged exposure of soil surface may lead to desertification in areas of low rainfall
Increase in soil temperature which speeds up the rate of humus decay
May lead to global warming due to the absence of green plants to remove carbon dioxide from the atmosphere for photosynthesis.
2. Bush Burning;
Loss of soil fertility due to burning of humus and soil micro-organisms
Increase in soil temperature
Death of plants and animals
Promotes soil erosion by exposing the soil
May cause global warming and greenhouse effect due to the accumulation of Carbon dioxide in the atmosphere.
3. Tillage;
Breaks up the soil surface, and loosens the soil for roots of young plants to grow
It mixes humus into the soil
It makes it easier for water to circulate in the soil
It however increases soil erosion and removes plant cover
4. Excessive use of fertilizers;
May kill useful soil organisms
Pollute the water if washed into nearby streams and rivers
May cause algal bloom(eutrophication),and make the water unfit for human use
Prolonged use of chemical fertilizers may lead to the development of poor soil structure
5. Pesticides and Herbicides;
May pollute the atmosphere since most of them are aerosols
Insecticides may kill insect pollinators such as butterflies and bees
Some crops eaten by man may absorb the chemicals and become contaminated.
Note: As an alternative to the use of chemicals, Biological control (use of predatory animals) is safer and environment-friendly in the control of pests, e.g. ladybird beetles or wasp’s larvae can be used to control aphids, while hunting spider can be used to control brown plant hoppers.
Different farming methods such as crop rotation, mixedcropping, mixedfarming, shifting cultivation, continuous cropping etc. have their respective effects on the ecosystem....