Account for the decline in the contribution of agriculture to the Gross Domestic Product (GDP) of Nigeria.

Agriculture once dominated Nigeria's Gross Domestic Product and exports, but its share declined sharply, especially after the oil boom. The main reasons are:

• Discovery and dominance of crude oil: the oil boom shifted attention, labour and government revenue to petroleum, so oil rather than agriculture came to dominate GDP and exports.
• Rural-urban migration: young people left farming for the towns in search of oil-sector and white-collar jobs, leaving an ageing farm labour force.
• Use of crude, traditional methods: continued reliance on the hoe and cutlass and on rain-fed farming keeps output low.
• Poor access to finance and credit for farmers, limiting investment in inputs and machinery.
• Inadequate infrastructure: poor rural roads, storage and processing facilities cause heavy post-harvest losses.
• Neglect of agriculture by government in favour of oil, with fewer incentives and less funding.
• Land tenure problems that make it hard to acquire large, secure holdings.
• Pests, diseases and unfavourable weather that reduce yields, plus low and unstable prices for farm produce.
• Lack of modern inputs such as improved seeds, fertilizer and irrigation.

In relative terms, agriculture's share fell largely because the oil sector grew so fast, while at the same time agriculture itself remained low-yielding and neglected.