Yam is a staple food in Nigeria, it is highly consumed by all tribe and region in the Country. It also has high demand internationally. Nigeria is the highest producer of yam in the world. Accounting for 70-77 percent of the total yam production in the world.
Yam is in the class of roots and tubers that is a staple of the Nigerian and West African diet, which provides some 200 calories of energy per capita daily. In Nigeria, in many yam-producing areas, it is said that “yam is food and food is yam”. However, the production of yam in Nigeria is substantially short and cannot meet the growing demand at its present level of use.
Therefore, there is need for more investment in the yam industry to meet the growing Nigerian population and also exportation.
Cultivation practices.
Soil.
Yam is grown on free draining, sandy and fertile soil, after clearing the first fallow. The land is prepared in the form of mound or ridge or heap of 1 metre in height. The yams recommended for such soil conditions in Nigeria are white yam or white guinea yam (Discorea rotundata) and water yam or yellow yam (Discorea alata).
Planting
Planting is done by seed yam or cut setts from ware tubers. One day before planting, the tubers have to be subjected to treatment with wood ash or a fungicide (thiabendazole) to prevent damage to the soils. The setts are planted at an interval of 15–20 centimetres (5.9–7.9 in) with the cut face facing up. The chemical prevent soil bore diseases and rotting of the seed or setts.
Staking.
This is the elevation of creeping vines above ground level by means of supporting structure usually wooden poles. Yam are usually staked before the vines start crawling on the ground. The recommended stake length is 2 metres. plant with wooden pole to vine over it. Staking provides each plant the ability to grow without bending to the point where it breaks the plant and stops growth. Having the plant grow upward after it is staked allows the plant exposes the plant to the required sunlight for growth.
Watering.
The plant must be watered regularly till the plant can survive by getting moist from the soil through it roots. In the absence of rain, the farm should be irrigated.
Weeding.
Weeding can be manually done by hoe depending on the size of the farm. It can be done three to four times depending on the rate of weed growth. It is important to weed it when the plant is still young to make enough nutrient available to the plant.
Mulching.
Mulching is the addition of decomposable materials to the soil surface to protect it from erosion and also to increase its nutritional quality. Mulch is an important practice in yam production. It is can done with dry grasses or plant debris. It can also be done with sawdust.
Fertilizer application.
Fertilizer can be added to the soil based on the soil need. The soil must be firstly tested for fertilizer deficiency before adding fertilizer to it. Fertilizer application is best done at 8- 10 weeks after planting. Fertilizer application is by banding. For low fertility classed soils, 400-500 kg/ha of inorganic NPK 20:10:10 fertilizer is regarded as adequate for optimum yield of yam.
Pest and disease control.
The main pests of yam is nematode the yam nematode while insects pest of yam are yam shoot beetle, yam tuber beetle and crickets, they are controlled by cultural method. Main yam disease is yam knot which is controlled by chemical.
Harvesting.
Harvesting is done before the vines become dry and soil becomes dry and hard. The stem is pulled from the soil to harvest the tuber.
