The term "Agriculture" has been subjected to different definitions by various experts. As a result Ighodo (1984: 20) defined agriculture as the art and science of the cultivation of crops and rearing of animals for man's use. He also emphasized that agriculture is also the production of fibres for industries, processing of farm produce, packaging and marketing of farm products. This definition is quite embracing as it covers all activities that ensure man's survival. However, the aspect of research and training that is so vital in production was conspicuously missing in the definition.
In order to fill this gap, Ogwuma (1985: 5-8) defines agriculture as production of field crops, forestry, fishing and livestock, research and training of extension workers.
Production is only complete when it gets to the final consumers. It is in response to this economic doctrine that Anyanwu (1987:102) defined agriculture as involving cultivation of land, raising and rearing of animals for the purpose of providing food for man, feed for animals and raw materials for industries. It involves forestry, fishing, processing and marketing of these agricultural products.
Komolafe (1985), Adegoye (1985) and Adubi (2000) defined agriculture as the cultivation of soil for crop production and of looking after animals to produce better meat and other food products and also a process by which farm products are sold.
Simon Kuznet (1973) defined economic growth as a long term rise in the capacity to supply increasingly diverse economic goods to its population. It entails a sustainable rise in national output which is a manifestation of economic growth.
To Anyanwu (1997), the role of agriculture in transforming both the social and economic framework of an economy cannot be over-emphasized. In effect, it has been the main source of gainful employment from which the nation can feed its teeming population, providing the nation's industries with local raw materials and as a reliable source of government revenue.
According to Adegoye and Dittah (1985), agricultural output can increase the level of income of farmers and the people. They said what constitutes the level of agricultural output will vary with the stage of economic development of a country.
For a purely subsistence economy, agricultural development will occur but not like in a fully developed economy. If there is enough food for the people and a marketable surplus is produced, it will increase the income of the peasants. The increased income generated would so provide means for them to purchase other necessities of life, which they cannot produce themselves. By this means, the standard of living of the peasants will improve and unemployment, underdevelopment will be reduced.
They stated that a fully developed economy, especially in agricultural sector, means increase in the production of export crops with an improvement in the quantity and grades of such export crops. For a country that has started to industrialize, agricultural output will be said to have acquired growth if agriculture can supply enough raw materials to the agro-allied industries.
Reynolds (1975: 215), revealed that agricultural development can promote the economic development by increasing the supply of food available for domestic consumption and releasing the labour needed for industrial employment. According to him, agricultural development can promote economic development of underdeveloped countries in four distinct ways:
i) By increasing the supply of food available for domestic consumption and releasing labour needed for industrial employment.
ii) By enlarging the size of the domestic market for the manufacturing sector.
iii) By increasing the supply of domestic savings and
iv) By providing foreign exchange earned by the agricultural exports.
Omawale and Rodriguez (1975) opined that for most developing countries, agriculture has been assigned an important role in national development. To them, agriculture has been seen as a means of reducing dependence on certain importations, containing food price increases, earning foreign exchange, absorbing many new entrants to the labour market and increasing farm incomes at times of severe unemployment and rural poverty.
According to J. C. Anyanwu, A. Oyefusi, H. Oaikhenan and F. A. Dimowo (1997), the role of agriculture in transforming both the social and economic framework of an economy cannot be over-emphasized. It is a source of food and raw materials for the industrial sector, it is also essential for expansion of employment opportunity, for reduction of poverty and improvement of income distribution, also for speeding up industrialization and easing the pressure on Balance of Payment. In effect, it has been the source of gainful employment from which the nation can feed its teeming population, providing the nation's industries with local raw materials and as a reliable source of government revenue.THE IMPACT OF AGRICULTURAL DEVELOPMENT ON ECONOMIC GROWTH OF NIGERIA