Nigeria

Nigeria

Nigeria , officially the Federal Republic of Nigeria, is a federal constitutional republic comprising 36 states and its Federal Capital Territory, Abuja. The country is located in West Africa and shares land borders with the Republic of Benin in the west, Chad and Cameroon in the east, and Niger in...

 is by far the world’s largest producer of yam

Yam (vegetable)

Yam is the common name for some species in the genus Dioscorea . These are perennial herbaceous vines cultivated for the consumption of their starchy tubers in Africa, Asia, Latin America and Oceania...

s, accounting for over 70–76 percent of the world production. According to the Food and Agricultural Organization report, in 1985, Nigeria produced 18.3 million tonnes of yam from 1.5 million hectares, representing 73.8 percent of total yam production in Africa

Africa

Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

. According to 2008 figures, yam production in Nigeria has nearly doubled since 1985, with Nigeria producing 35.017 million metric tonnes with value equivalent of US$5.654 billion. In perspective, the world's second and third largest producers of yams, Côte d'Ivoire

Côte d'Ivoire

The Republic of Côte d'Ivoire or Ivory Coast is a country in West Africa. It has an area of , and borders the countries Liberia, Guinea, Mali, Burkina Faso and Ghana; its southern boundary is along the Gulf of Guinea. The country's population was 15,366,672 in 1998 and was estimated to be...

 and Ghana

Ghana

Ghana , officially the Republic of Ghana, is a country located in West Africa. It is bordered by Côte d'Ivoire to the west, Burkina Faso to the north, Togo to the east, and the Gulf of Guinea to the south...

, only produced 6.9 and 4.8 tonnes of yams in 2008 respectively. According to the International Institute of Tropical Agriculture

International Institute of Tropical Agriculture

International Institute of Tropical Agriculture is one of the world's leading research partners in finding solutions to hunger, malnutrition, and poverty. IITA's award-winning research-for-development addresses the development needs of tropical countries...

, Nigeria accounted for about 70 percent of the world production amounting to 17 million tonnes from land area 2,837,000 hectares under yam cultivation.

Yam, a tropical crop in the genus Dioscorea

Dioscorea

Dioscorea is a genus of over 600 species of flowering plants in the family Dioscoreaceae, native throughout the tropical and warm temperate regions of the world. The vast majority of the species are tropical, with only a few species extending into temperate climates...

, has as many as 600 species out of which six are economically important staple species. These are: Dioscorea rotundata

Dioscorea rotundata

Dioscorea rotundata, the "white yam", is a species of yam native to Africa. It is one of the most important cultivated yams, along with the Dioscorea cayenensis. It is sometimes known as the "Guinea Yam" D...

(white guinea yam), Dioscorea alata (yellow yam), Dioscorea bulbifera

Dioscorea bulbifera

Dioscorea bulbifera, the Air potato, is a yam species. It is also known as Varahi in Sanskrit, Kaachil in Malayalam and Dukkar Kand in Marathi. The Air potato plant is native to Africa and Asia.-Description:...

(aerial yam), Dioscorea esculant (Chinese yam) and Dioscorea dumetorum (trifoliate yam). Out of these, Dioscorea rotundata (white yam) and Dioscorea alata (water yam) are the most common species in Nigeria. Yams are grown in the coastal region in rain forests, wood savanna and southern savanna

Savanna

A savanna, or savannah, is a grassland ecosystem characterized by the trees being sufficiently small or widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of C4 grasses.Some...

 habitats.

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. It also has an important social status in gatherings and religious functions, which is assessed by the size of yam holdings one possesses.

Geographic regions

The farmland production system in the Ekiti State consists of wetland (20% farms are under this category), upland (50% farms in this category) types and a combination of the two types (30% by the balance farms). A study carried out on the efficiency of the three systems to improve crop outputs to meet growing demands for this food crop, indicates that the "wetland yam based enterprises are the most economically efficient with mean economic efficiency of 0.80 followed by upland yam based enterprises with mean efficiency of 0.79." The combination of wetland/upland yam based enterprises is assessed as the least economically efficient, with mean efficiency of 0.76. Hence, it has been recommended that more yams should be grown more on wetlands. Another recommendation made is to adopt the yam minisett technology developed by the International Institute for Tropical Agriculture (IITA) and the National Root Crops Research Institute (NRCRI).

Although it is grown widely in Nigeria, the area where it is grown most is the Enugu State

Enugu State

Enugu State is a mainland state in southeastern Nigeria. Its capital is Enugu, from which the state - created in 1991 from the old Anambra State - derives its name. The principal cities in the state are Enugu, Agbani, Awgu, Udi, Oji, and Nsukka....

 (land area of 802,295 km²) one of the five states in southeastern Nigeria where the labour intensive practices are still the norm and the land holdings are small. They are planted on mounds rather than flat slopes depending on the hydromorphic nature of the soils which are generally of loose soil suitable to grow roots and tuber crops. While yam production issues have been stressed on agronomical practices, a research study carried out on the economic efficiency of this crop grown in this region with small farm holdings, which is labour intensive, reveals that land, labour and material (fertilizers and chemicals), credit and extension services inputs have a significant bearing on the yield of yam in the region.

Cultivation practices

Yam is grown on free draining, sandy and fertile soil, after clearing the first fallow. Land is prepared in the form of mound or ridge or heap of 1 metres (3.3 ft) 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 is done by seed

Seed

A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...

 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

Fungicide

Fungicides are chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality and profit. Fungicides are used both in agriculture and to fight fungal infections in animals...

 (thiabendazole

Thiabendazole

Tiabendazole is a fungicide and parasiticide.-Fungicide:...

) to prevent damage to the soils. The setts are planted at an interval of 15–20 cm (5.9–7.9 ) with the cut face facing up. Mulching is essential during October–November with dry grass or plant debris weighed down with balls of mud. Dosage of fertilizer application, as essential, is decided after chemical analysis of the soil samples. Manual weeding by hoeing is done three or four times depending on the rate of weed growth. Two Stakes, each of 2 metres (6.6 ft) height are used for staking the plants to vine over it; one for two plants with the other used for bracing with the adjacent stakes. Sorghum

Sorghum

Sorghum is a genus of numerous species of grasses, one of which is raised for grain and many of which are used as fodder plants either cultivated or as part of pasture. The plants are cultivated in warmer climates worldwide. Species are native to tropical and subtropical regions of all continents...

 stover

Stover

Stover is the leaves and stalks of corn , sorghum or soybean plants that are left in a field after harvest. It can be directly grazed by cattle or dried for use as fodder. It is similar to straw, the residue left after any cereal grain or grass has been harvested at maturity for its seed...

s are also used for this purpose in the savannah

Savannah

Savannah or savanna is a type of grassland.It can also mean:-People:* Savannah King, a Canadian freestyle swimmer* Savannah Outen, a singer who gained popularity on You Tube...

 land. Pest and disease control is addressed by cultural control and chemical methods; the pests which affect the plant are nematode

Nematode

The nematodes or roundworms are the most diverse phylum of pseudocoelomates, and one of the most diverse of all animals. Nematode species are very difficult to distinguish; over 28,000 have been described, of which over 16,000 are parasitic. It has been estimated that the total number of nematode...

s such as root knot Meloidogyne spp.

Root-knot nematode

Root-knot nematodes are plant-parasitic nematodes from the genus Meloidogyne. They exist in soil in areas with hot climates or short winters. About 2000 plants are susceptible to infection by root-knot nematodes and they cause approximately 5% of global crop loss...

 and yam nematode (Scutellonema bradys), and insects such as yam shoot beetle

Beetle

Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...

, yam tuber beetle and crickets

Cricket (insect)

Crickets, family Gryllidae , are insects somewhat related to grasshoppers, and more closely related to katydids or bush crickets . They have somewhat flattened bodies and long antennae. There are about 900 species of crickets...

. Weeding of the field is essential and maintaining a 2–3 m (6.6–9.8 ) weed free border around the field is to be ensured. Disease resistant [cultivars] are normally recommended for use. Harvesting is done before the vines become dry and soil becomes dry and hard. Generally, a yield of 10–15 tonnes per ha for white yam and 16–25 tonnes for water yam are obtained by following prescribed management practices. The harvested yams are stored by tying them with ropes. They have a shelf life of about 5 months. Warehouses where they are stored should be made rodent proof with a metal base and wire netting. Rotten buds and sprouted buds should be removed.

Uses

Tuber is the main part of the yam plant which has high carbohydrate

Carbohydrate

A carbohydrate is an organic compound with the empirical formula ; that is, consists only of carbon, hydrogen, and oxygen, with a hydrogen:oxygen atom ratio of 2:1 . However, there are exceptions to this. One common example would be deoxyribose, a component of DNA, which has the empirical...

 content (low in fat and protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

) and provides a good source of energy. Unpeeled yam has vitamin C

Vitamin C

Vitamin C or L-ascorbic acid or L-ascorbate is an essential nutrient for humans and certain other animal species. In living organisms ascorbate acts as an antioxidant by protecting the body against oxidative stress...

. Yam, sweet in flavour, is consumed as boiled yam (as cooked vegetable) or fufu or fried in oil and then consumed. It is often pounded into a thick paste after boiling and is consumed with soup. It is also processed into flour for use in the preparation of the paste. Its medicinal use as a heart stimulant is attributed to its chemical composition, which consists of alkaloids of saponin

Saponin

Saponins are a class of chemical compounds, one of many secondary metabolites found in natural sources, with saponins found in particular abundance in various plant species...

 and sapogenin

Sapogenin

Sapogenins are the aglycones, or non-saccharide, portions of the family of natural products known as saponins. Sapogenins contain steroid or other triterpene frameworks as their key organic feature. For example, steroidal sapogenins like tiggenin, neogitogenin, and tokorogenin have been isolated...

. Its use as an industrial starch has also been established as the quality of some of the species is able to provide as much starch as in cereals.

Rituals and festivals

Ritualism and festivity restriction are also associated with yam, which is the staple in southeastern Nigeria. A yam festival is held every year to mark the harvesting of this crop. The village chiefs and traditional title holders of lands in Nigeria who grow yam make it a religious practice by not consuming yam till it is offered to the gods. During this festival, villagers offer prayers thanking their ancestral gods for the blessings of the land and the women's fertility. The festivity observed in villages is in the form of a parade of traditional dances.

Customs

One of the marriage custom observed in some communities in Nigeria is to measure the bridegroom's wealth by the amount of yams that he can produce. Also, according to tradition, the groom has to present a minimum of 200 big tubers of yams to the in-laws as a proof that he can take care of his wife and the future family.

Yam is depicted as a male totem

Totem

A totem is a stipulated ancestor of a group of people, such as a family, clan, group, lineage, or tribe.Totems support larger groups than the individual person. In kinship and descent, if the apical ancestor of a clan is nonhuman, it is called a totem...

in some areas of the Ibo land. Another custom observed is that women are not permitted to go to the yam farms till it is ready for harvesting; however, harvesting of the crop is the prerogative of the women.