Plants which are good sources of food for both man and animals are of great benefit to us as we can not do without them. They are good sources of food, medicinal source, used in beautification, etc.
Plants are classified based on their
1. BOTANICAL CLASSIFICATION
A. Thallophytes which are simple plants consisting of algae, and fungi.
B.Bryophyta which consists of the liverworts and mosses which live in damp places.
C. Pteridophyta which consists of the ferns and some cone bearing plants.
D. Spermatophyta which consists of the gymnospermae and angiospermae.
2. AGRICULTURAL CLASSIFICATION
A. Fibres which consists of cotton, jute, hemp and sisal.
B. Latex which consist of rubber.
C. Root crops which consists of yams, cassava, potatoes, and cocoyams.
D. Fruits which consists of citrus, pawpaw, mangoes, pineapples,etc.
E. Cereals which consists of rice, maize, guinea corn.
F. Legumes which consists of beans, soyabeans, cow-peas, and groundnuts.
G. Beverages and Drugs which consist of coffee, cocoa, sugarcane, kolanuts.
H. Spices which consists of pepper and ginger.
I. Vegetables which consists of tomatoes, okro, carrots, lettuce.
3. CLASSIFICATION BASED ON LIFE CYCLE
1. Ephemerals which are plants that complete their life cycle in few weeks. e.g Water leaf.
2. Annuals which are plants that complete their life cycle in one year. e.g. maize, tomatoes, rice, garden eggs,and yams.
3. Biennials which are flowering plants that complete their life cycle in two years. e.g. onions and carrots.
4. Perennials which are plants that completes their life cycle in more than two years.e.g. mangoes and oranges.
EFFECTS OF AGRICULTURAL ACTIVITIES ON ECOLOGICAL SYSTEMS
1. Bush burning reduces organic content of soil, increases inorganic content of soil and destroys soil microorganism.
2.Tillage leads to soil erosion and aeration.
3. Fertilizer application changes soil pH, alters the chemical composition of the soil and adds nutrients to the soil.
4. Herbicides and pesticides pollute water and land.
5. Irrigation leads to high humidity of the soil.
6. Overgrazing leads to loss of soil nutrients which may be recovered in a long run.
7. Different farming methods affects soil topography.
Agricultural systems which destroys the balance of an ecosystem are as follows;
1. Deforestation which is the cutting down of trees exposes the soil to forces of wind/rain which results in erosion and poor nutrients to support plant’s life. This result in low animal population which is associated with plants.
2. Continuous cropping which is the repeated cultivation of crops in one area of land reduces the soil nutrient.
3. Excessive use of fertilizers which brings about loss of the organic matter or humus. It causes deterioration of the structure of the soil and increases the porosity of the soil. These affect life of plant and animals.
4. Bush burning which destroys essential nutrients, reduces water holding properties of the soil, brings about low support of plants and animals and kills microbial flora, fauna and organisms in the soil.
5. Overgrazing removes vegetation or leaves of little plants cover on the soil. The soil dries out quickly and may be eroded.
6. Mono cropping provides abundant food for pests of the vastly cultivated crops which causes the population of pests to increase greatly and therefore increasing their harmful effects. The large population of pests reduces the food and population of other animals whose natural food is not readily available.
DIFFERENT TYPES OF FARMING
There are different types of farming which includes the following;
1. Arable farming which involves the cultivation of crops only.
2. Pastoral farming which involves the rearing of grazing animals alone.
3. Dairy Farming which involves the rearing of animals for sole purpose of producing milk.
4. Mixed farming which is the integration of animal and crop production on the same farm. This method of farming provides crop plants with the farm yard manure from animals while some crop plants are used as food for animals.
Arable farming involves two kinds which are listed below;
1. Mono cropping: this is the planting of one type of crop on the farm. It is very suitable for mechanized farming and large scale production of a particular plant product. Although, it leads to the loss of soil fertility and rapid spread of pests and diseases in farms.
2. Mixed farming: this involves growing more than one type of crop on the same piece of land. It makes the spread of pests and diseases more difficult since identical plants are more widely separated. It is not applicable to large scale mechanization as each type of crop requires different type of handling which a machine may not carry out well.