Explanation:
(a) Difference between subsistence agriculture and commercial agriculture
Subsistence Agriculture

Production is mainly for family consumption
Less capital is required
Uses family labour/unskilled labour
Use of local breeds of animals
Use of local crop varieties
Hardly use agro-chemicals/Cultural methods are used to control pests and diseases
Records are rarely kept Use of primitive/local tools
Poor housing facilities for rearing animals
Peasant farmers are involved
Doer not require improved processing facilities
Does not involve any marketing Uses crude storage facilities
Yield per unit area is low
Food crops are produced
Small area of land is cultivated
Use of inorganic fertilizers is limited

Commercial Agriculture

Production is mainly for sale
Huge amount of capital is required
Skilled/hired labour is employed
Use of exotic/improved breeds of animals
Use of improved crop varieties
Mostly use agro-chemicals
Records are kept Mechanized/use of machines
Modern housing facilities for rearing animals
Farmers involved may be rich
Requires improved processing facilities
Requires organised market Uses modern storage facilities
Yield per unit area is high
Cash crops are produced
Large area of land may be cultivated
Frequent use of inorganic fertilizers

(b) Possible solutions to each of the following problems of agricultural development in West Africa (i) Inadequate land:
- Leasehold land tenure system should be encouraged to enable farmers to acquire land for temporary use
- Land rates/rents should be reduced especially for agricultural purposes
- Government laws on land use should be made favourable to enable farmers acquire land easily
- Farmers should form co-operative societies to enable them pull their resources together to acquire large hectares of land for cultivation
- Farm settlements should be established to facilitate acquisition of land by farmers
- Creation of land banks
(ii)Inadequate finance;
- Agricultural banks should be established by the government to provide loans to farmers with minimum collateral
- Farmers should form co-operative societies to enable them access credit facilities
- Subsidies should be given to farmers by government/other agencies
- Agricultural insurance scheme/policies should be made available to farmers
- Commercial banks should be encouraged to give loans to farmers at low interest rates
-Grants should be given to farmers either in cash or in kind
(iii) Incidence of diseases
- Diseases resistant varieties of crops and breeds of animals should be developed for farmers by government and research institutes
- Plant protection chemicals and livestock drugs should be provided for farmers b government non-governmental agencies
- Vaccines should be produced locally to prevent livestock diseases
- Veterinary services should be provided to livestock farmers
- Extension workers should assist farmers in the detection and control of crop and animal diseases
- Cultural measures/practices used in controlling abiotic components of the environment crop diseases should be embraced by farmers
(c) Definition of Agricultural Ecology It is study of the relationships and interactions between crops and animals and their biotic and abiotic components of the environment
(d)(i) Sources of pollution of agricultural lands and fish ponds
Oil spillage, Improper sewage disposal, Improper livestock waste disposal, Excessive application of pesticides, Excessive application of fertilizers, Excessive application of herbicides, Improper dumping of toxic wastes, Improper disposal of industrial waste/effluent