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61-417: The dam has a capacity of 450 million cubic meters, with a reservoir covering 8,000 hectares extending 19 km (12 mi) upstream. Dam construction displaced many peasant farmers without providing alternative land or financial compensation. Many people died in protests over their loss of livelihood. The project has become known as a classic example of development failure. The Sokoto River runs through

122-679: A dash ; for example, 1-21-00.26 ha would mean 1 hectare, 21 ares, and 0.26 centiares (12,100.26 m ). The metric system of measurement was first given a legal basis in 1795 by the French Revolutionary government. The law of 18 Germinal, Year III (7 April 1795) defined five units of measure: In 1960, when the metric system was updated as the International System of Units (SI), the are did not receive international recognition. The International Committee for Weights and Measures ( CIPM ) makes no mention of

183-404: A double prefix is non-standard. The decimilliare is (100 mm) or roughly a four-inch-by-four-inch square. The centiare is one square metre. The deciare (rarely used) is ten square metres. The are ( / ɑːr / or / ɛər / ) is a unit of area, equal to 100 square metres ( 10 m × 10 m ), used for measuring land area. It was defined by older forms of the metric system , but

244-456: A pest deterrent . CpTI is the only gene obtained outside of B. thuringiensis that has been inserted into a commercially available genetically modified crop. Besides biotic stresses, cowpea also faces various challenges in different parts of the world such as drought, heat, and cold. Drought lowers the growth rate and development, ultimately reducing yield, although cowpea is considered more drought tolerant than most other crops. Drought at

305-439: A few other units including the are (and implicitly the hectare ) whose use was limited to the measurement of land. The names centiare , deciare , decare and hectare are derived by adding the standard metric prefixes to the original base unit of area, the are . The decimilliare (dma, sometimes seen in cadastre area evaluation of real estate plots) is 1 ⁄ 10,000 are or one square decimetre. Such usage of

366-475: A half long") and the common names of yardlong bean, asparagus bean, and Chinese long-bean. Group Common name A large morphological diversity is found within the crop, and the growth conditions and grower preferences for each variety vary from region to region. However, as the plant is primarily self-pollinating , its genetic diversity within varieties is relatively low. Cowpeas can either be short and bushy (as short as 20 cm or 8 in) or act like

427-451: A hot and arid area loses much to evaporation. In the downstream areas, of a total of 19,000 hectares of floodplain land, the dam resulted in loss of 7,000 hectares of rice production and 5,000 hectares of dry season crops. This loss was partially offset by increases in lower-value millet and sorghum production, but 12,000 people were forced to move. The loss of agricultural output has been valued at US$ 7 million annually. The reservoir has

488-591: A key role in subsistence farming and livestock fodder, the cowpea is also seen as a major cash crop by Central and West African farmers, with an estimated 200 million people consuming cowpea on a daily basis. According to the Food and Agriculture Organization of the United Nations , as of 2012, the average cowpea yield in Western Africa was an estimated 483 kilograms per hectare (431 lb/acre), which

549-426: A major food crop. A seed can consist of 25% protein and has very low fat content. Cowpea starch is digested more slowly than the starch from cereals, which is more beneficial to human health. The grain is a rich source of folic acid , an important vitamin that helps prevent neural tube defects in unborn babies. The cowpea has often been referred to as "poor man's meat" due to the high levels of protein found in

610-550: A measure of land area. The names of the older land measures of similar size are usually used, redefined as exactly one decare: The most commonly used units are in bold . One hectare is also equivalent to: The Unicode character U+33CA ㏊ SQUARE HA , in the CJK Compatibility block, is intended for compatibility with pre-existing East Asian character codes. It is not intended for use in alphabetic contexts. U+3336 ㌶ SQUARE HEKUTAARU

671-415: A relatively small littoral area, which limits the size of spawning and nursery areas of most fish species. The water is turbid, holding suspended soil particles that block the light and inhibit growth of submerged aquatic plants on which fish depend for food. This limits the capacity of the reservoir for fish production. The reservoir is less productive than the river and the river's natural lakes and pools. In

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732-586: A sexually mature adult within the seed. An individual bruchid can lay 20–40 eggs, and in optimal conditions, each egg can develop into a reproductively active adult in 3 weeks. The most common methods of protection involve the use of insecticides, the main pesticides used being carbamates , synthetic pyrethroids , and organophosphates . Cowpea is susceptible to nematode , fungal, bacterial, and virus diseases, which can result in substantial loss in yield. Common diseases include blights , root rot, wilt, powdery mildew , root knot, rust and leaf spot . The plant

793-669: A unit of SI, is the only named unit of area that is accepted for use with SI units . The name was coined in French, from the Latin ārea . In practice the hectare is fully derived from the SI, being equivalent to a square hectometre. It is widely used throughout the world for the measurement of large areas of land, and it is the legal unit of measure in domains concerned with land ownership, planning, and management , including law ( land deeds ), agriculture, forestry , and town planning throughout

854-409: A valuable crop for resource-poor farmers and well-suited to intercropping with other crops. The whole plant is used as forage for animals, with its use as cattle feed likely responsible for its name. Four subspecies of cowpeas are recognised, of which three are cultivated. A high level of morphological diversity is found within the species with large variations in the size, shape, and structure of

915-447: A vine by climbing supports or trailing along the ground (to a height of 2 m or 6 ft 7 in). The taproot can penetrate to a depth of 2.4 m (7 ft 10 in) after eight weeks. The size and shape of the leaves vary greatly, making this an important feature for classifying and distinguishing cowpea varieties. Another distinguishing feature of cowpeas is the long 20–50 cm (8–20 in) peduncles , which hold

976-609: Is koki or moin-moin , where the cowpeas are mashed into a paste, mixed with spices and steamed in banana leaves. They also use the cowpea paste as a supplement in infant formula when weaning babies off milk. Slaves brought to America and the West Indies cooked cowpeas much the same way as they did in Africa, although many people in the American South considered cowpeas not suitable for human consumption. A popular dish

1037-505: Is a combination of ヘクタール ( hekutāru ), the Japanese translation of "hectare". Cowpea The cowpea ( Vigna unguiculata ) is an annual herbaceous legume from the genus Vigna . Its tolerance for sandy soil and low rainfall have made it an important crop in the semiarid regions across Africa and Asia . It requires very few inputs, as the plant's root nodules are able to fix atmospheric nitrogen , making it

1098-488: Is about 0.405 hectares and one hectare contains about 2.47 acres. In 1795, when the metric system was introduced, the are was defined as 100 square metres , or one square decametre , and the hectare (" hecto- " + "are") was thus 100 ares or 1 ⁄ 100  km (10,000 square metres). When the metric system was further rationalised in 1960, resulting in the International System of Units ( SI ),

1159-463: Is no archaeological evidence for early cowpea cultivation, the centre of diversity of the cultivated cowpea is West Africa, leading an early consensus that this is the likely centre of origin and place of early domestication. New research using molecular markers has suggested that domestication may have instead occurred in East Africa and currently both theories carry equal weight. While

1220-456: Is now outside the modern International System of Units (SI). It is still commonly used in speech to measure real estate, in particular in Indonesia, India, and in various European countries. In Russian and some other languages of the former Soviet Union , the are is called sotka (Russian: сотка : 'a hundred', i.e. 100 m or 1 ⁄ 100 hectare). It is used to describe

1281-410: Is still 50% below the estimated potential production yield. In some tradition cropping methods, the yield can be as low as 100 kilograms per hectare (89 lb/acre). Outside Africa, the major production areas are Asia, Central America , and South America . Brazil is the world's second-leading producer of cowpea seed, accounting for 17% of annual cowpea production, although most is consumed within

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1342-503: Is subject to periodic droughts, and the desire for a stable water supply was one of the motives for constructing the dam. In 1969, the Food and Agriculture Organization (FAO) issued a report that recommended a small dam and irrigation scheme at Talata Mafara , with further upstream dams for flood control. The FAO report emphasized the importance of a gradual approach that would have minimal impact on existing land use patterns, in part because of lack of experience with irrigation projects in

1403-475: Is susceptible to mosaic viruses , which cause a green mosaic pattern to appear in the leaves. The cowpea mosaic virus (CPMV), discovered in 1959, has become a useful research tool. CPMV is stable and easy to propagate to a high yield, making it useful in vector development and protein expression systems . One of the plant's defenses against some insect attacks is the cowpea trypsin inhibitor (CpTI). CpTI has been transgenically inserted into other crops as

1464-492: Is the main exporter of cowpeas and Nigeria the main importer. Exact figures for cowpea production are hard to come up with as it is not a major export crop. Estimating world cowpea production is rather difficult, as it is usually grown in a mixture with other crops, but according to a 1997 estimate, cowpeas were cultivated on 12.5 million hectares (31 million acres) and had a worldwide production of 3 million metric tons (3,000,000 long tons; 3,300,000 short tons). While they play

1525-511: Is the main preharvest pest of the cowpea and the cowpea weevil Callosobruchus maculatus the main postharvest pest. Vigna unguiculata is a member of the Vigna (peas and beans) genus. Unguiculata is Latin for "with a small claw", which reflects the small stalks on the flower petals. Common names for cultivated cowpeas include black-eye pea, southern pea, niebe (alternatively ñebbe), and crowder pea. All cultivated cowpeas are found within

1586-409: Is the main preharvest pest of the cowpea. Other important pests include pod sucking bugs , thrips , aphids , cowpea curculios and post-harvest beetles Callosobruchus maculatus and Callosobruchus chinensis . M. vitrata causes the most damage to the growing cowpea due to their large host range and cosmopolitan distribution . It causes damage to the flower buds, flowers, and pods of

1647-484: Is toxic to lepidopteran species including the maruca. BT Cowpea was commercialised in Nigeria in 2019. Severe C. maculatus infestations can affect 100% of the stored peas and cause up to 60% loss within a few months. The weevil generally enters the cowpea pod through holes before harvest and lays eggs on the dry seed. The larvae burrow their way into the seed, feeding on the endosperm . The weevil develops into

1708-1151: The European Union , New Zealand and Australia (since 1970). However, the United Kingdom, the United States, Myanmar (Burma), and to some extent Canada, use the acre instead of the hectare for measuring surface or land area. Some countries that underwent a general conversion from traditional measurements to metric measurements (e.g. Canada) required a resurvey when units of measure in legal descriptions relating to land were converted to metric units. Others, such as South Africa, published conversion factors which were to be used particularly "when preparing consolidation diagrams by compilation". In many countries, metrification redefined or clarified existing measures in terms of metric units. The following legacy units of area have been redefined as being equal to one hectare: In Mexico, land area measurements are commonly given as combinations of hectares, ares, and centiares. These are commonly written separated by

1769-593: The are in the 2019 edition of the SI brochure, but classifies the hectare as a "Non-SI unit accepted for use with the International System of Units". In 1972, the European Economic Community (EEC) passed directive 71/354/EEC, which catalogued the units of measure that might be used within the Community. The units that were catalogued replicated the recommendations of the CGPM, supplemented by

1830-403: The are was not included as a recognised unit. The hectare, however, remains as a non-SI unit accepted for use with the SI and whose use is "expected to continue indefinitely". Though the dekare/decare daa (1,000 m ) and are (100 m ) are not officially "accepted for use", they are still used in some contexts. The hectare ( / ˈ h ɛ k t ɛər , - t ɑː r / ), although not

1891-425: The hilum of the seed. Black-eyed peas were first introduced to the southern states in the United States and some early varieties had peas squashed closely together in their pods, leading to the other common names of southern pea and crowder pea. The sesquipedalis subspecies arrived in the United States via Asia. It is characterised by unusually long pods, leading to the Latin name ( sesquipedalis means "foot and

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1952-576: The African continent, particularly in Nigeria and Niger , which account for 66% of world production. A 1997 estimate suggests that cowpeas are cultivated on 12.5 million hectares (31 million acres) of land, have a worldwide production of 3 million tonnes and are consumed by 200 million people on a daily basis. Insect infestation is a major constraint to the production of cowpea, sometimes causing over 90% loss in yield. The legume pod borer Maruca vitrata

2013-520: The Greeks and Romans. The first written references to the cowpea were in 300 BC and they probably reached Central and North America during the slave trade through the 17th to early 19th centuries. Cowpeas thrive in poor dry conditions, growing well in soils up to 85% sand. This makes them a particularly important crop in arid, semidesert regions where not many other crops will grow. As well as an important source of food for humans in poor, arid regions,

2074-641: The crop can also be used as feed for livestock. Its nitrogen-fixing ability means that as well as functioning as a sole crop, the cowpea can be effectively intercropped with sorghum , millet , maize , cassava , or cotton . The optimum temperature for cowpea growth is 30 °C (86 °F), making it only available as a summer crop for most of the world. It grows best in regions with an annual rainfall between 400 and 700 mm (16 and 28 in). The ideal soils are sandy and it has better tolerance for infertile and acid soil than most other crops. Generally, 133,000 seeds are planted per hectare (54,000/acre) for

2135-519: The crop can thrive in the semiarid climate , where rainfall is often less than 500 mm (20 in). The timing of planting is crucial, as the plant must mature during the seasonal rains. The crop is mostly intercropped with pearl millet , and plants are selected that provide both food and fodder value instead of the more specialised varieties. Storage of the seeds can be problematic in Africa due to potential infestation by postharvest pests. Traditional methods of protecting stored grain include using

2196-554: The date of cultivation began may be uncertain, it is still considered one of the oldest domesticated crops. Remains of charred cowpeas from rock shelters in Central Ghana have been dated to the 2nd millennium BC . In 2300 BC, the cowpea is believed to have made its way into Southeast Asia, where secondary domestication events may have occurred. From there they traveled north to the Mediterranean, where they were used by

2257-544: The dry season. Many farmers used the Shadoof practice of lifting water from the river to pour into irrigation channels or ponds. Women in purdah do not usually work the field but do have ownership rights and assist in processing. Women who are not under seclusion are active in farming. Often the land was owned communally without formal records of ownership. Farmers in the area, living at subsistence levels, were more concerned with avoiding risk than maximizing profit. The area

2318-506: The erect varieties and 60,000 per hectare (24,000/acre) for the climbing and trailing varieties. The seeds can be harvested after about 100 days or the whole plant used as forage after about 120 days. Leaves can be picked from 4 weeks after planting. These characteristics, along with its low fertilisation requirements, make the cowpea an ideal crop for resource-poor farmers living in the Sahel region of West Africa. Early-maturing varieties of

2379-426: The flowers and seed pods. One peduncle can support four or more seed pods. Flower colour varies through different shades of purple, pink, yellow, and white and blue. Seeds and seed pods from wild cowpeas are very small, while cultivated varieties can have pods between 10 and 110 cm (4 and 43 in) long. A pod can contain six to 13 seeds that are usually kidney-shaped, although the seeds become more spherical

2440-415: The growing season, with diminished flows later as they practiced flood recession agriculture. Dam operators were not sensitive to this need, releasing insufficient water at inappropriate times. The dam significantly decreased peak flows and the depth, duration and extent of flooding downstream during the wet season. It also reduced the total amount of water available for farming, since a large sheet of water in

2501-494: The insecticidal properties of Neem extracts, mixing the grain with ash or sand, using vegetable oils, combining ash and oil into a soap solution or treating the cowpea pods with smoke or heat. More modern methods include storage in airtight containers, using gamma irradiation, or heating or freezing the seeds. Temperatures of 60 °C (140 °F) kill the weevil larvae, leading to a recent push to develop cheap forms of solar heating that can be used to treat stored grain. One of

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2562-406: The irrigated area, the higher water table combined with high evaporation rates has caused salinization, which has already ruined half of the irrigable land. There were also higher levels of water-born diseases. Attempts to introduce new varieties of cowpea inter-cropped with millet, sorghum and groundnuts had little success due to the relatively low yield of this traditional crop and the high cost of

2623-450: The irrigation systems. By 2003, the sprinkler system was no longer operational and only 7,500 hectares were being cultivated, mostly for rice, using gravity-fed irrigation. Land was left untilled. Many residents drifted away to the cities. The Bakolori Dam resulted in a 53% decrease in the usable cropped area. The authors of a report on Wise Use of Wetlands published by UNESCO in 1988 concluded that "a more complete economic appraisal of

2684-510: The leaves, green seeds and pods can also be consumed, meaning the cowpea can be used as a food source before the dried peas are harvested. Like other legumes , cowpeas are cooked to make them edible, usually by boiling. Cowpeas can be prepared in stews, soups, purees, casseroles and curries. They can also be processed into a paste or flour. Chinese long beans can be eaten raw or cooked, but as they easily become waterlogged are usually sautéed, stir-fried, or deep-fried. A common snack in Africa

2745-512: The local farmers were deprived of the means to make a living for several years. Confronted by demonstrators in November 1979, the governor of Sokoto State, Shehu Kangiwa , promised to address all their grievances. However, on 28 April 1980 police moved in on unarmed demonstrators and killed over 380 people. The government played down the incident, claiming only 25 had died. The downstream floodplain farmers required large-scale water release before

2806-403: The more recent developments is the use a cheap, reusable double-bagging system (called PICs ) that asphyxiates the cowpea weevils. Insects are a major factor in the low yields of African cowpea crops, and they affect each tissue component and developmental stage of the plant. In bad infestations, insect pressure is responsible for over 90% loss in yield. The legume pod borer, Maruca vitrata ,

2867-401: The more restricted they are within the pod. Their texture and colour are very diverse. They can have a smooth or rough coat and be speckled, mottled, or blotchy. Colours include white, cream, green, red, brown, and black, or various combinations. Compared to most other important crops, little is known about the domestication , dispersal, and cultivation history of the cowpea. Although there

2928-509: The nutritional value of the leaves and immature pods, what is available suggests that the leaves have a similar nutritional value to black nightshade and sweet potato leaves, while the green pods have less antinutritional factors than the dried seeds. Most cowpeas are grown on the African continent, particularly in Nigeria and Niger, which account for 66% of world cowpea production. The Sahel region also contains other major producers such as Burkina Faso , Ghana , Senegal , and Mali . Niger

2989-526: The planning process and no study was made of the downstream impact. Construction of the dam began in 1974 and was completed in 1978, after which it took three years for the reservoir to fill. The dam is a 5.5 km (3 mi) earth-fill embankment, with a central concrete structure 360 m long and 48 m high incorporating a small 3 MW hydroelectric power plant. The irrigation pipes and canals were not completed until 1983 and covered only 23,000 hectares compared to 30,000 hectares originally planned. Water

3050-399: The plant, with infestations resulting in a 20–88% loss of yield. While the insect can cause damage through all growth stages, most of the damage occurs during flowering. Biological control has had limited success, so most preventive methods rely on the use of agrichemicals . Genetically modified cowpeas has been developed to express the cry protein from Bacillus thuringiensis , which

3111-625: The plant. Cowpeas can be erect, semierect ( trailing ), or climbing . The crop is mainly grown for its seeds, which are high in protein , although the leaves and immature seed pods can also be consumed. Cowpeas were domesticated in Africa and are one of the oldest crops to be farmed. A second domestication event probably occurred in Asia, before they spread into Europe and the Americas. The seeds are usually cooked and made into stews and curries, or ground into flour or paste. Most cowpeas are grown on

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3172-576: The preflowering stage in cowpea can reduce the yield potential by 360 kg/ha. Crop wild relatives are the prominent source of genetic material, which can be tapped to improve biotic/abiotic tolerance in crops. International Institute of Tropical Agriculture (IITA), Nigeria and Institut de l’Environment et de Recherches Agricoles are looking to tap into the genetic diversity of wild cowpeas and transfer that into cultivars to make them more tolerant to different stresses and adaptive to climate change. Cowpeas are grown mostly for their edible beans, although

3233-495: The region. In 1971 the Nigerian military government invited proposals for design and supervision of the project and, in 1972, awarded the job to Impressit Bakolori Nigeria, a company owned 60% by the Nigerian government and 40% by a subsidiary of Fiat . During the 1972 to 1974 study period, the scope of the project expanded to cover a single large dam and a large-scale mechanized irrigation scheme. Local farmers were not consulted in

3294-443: The scheme at Bakolori would have been less favourable than the calculation upon which it was approved." Hectare The hectare ( / ˈ h ɛ k t ɛər , - t ɑːr / ; SI symbol: ha ) is a non-SI metric unit of area equal to a square with 100- metre sides (1 hm ), that is, 10,000 square metres (10,000 m ), and is primarily used in the measurement of land. There are 100 hectares in one square kilometre. An acre

3355-434: The seeds and leaves. However, it does contain some antinutritional elements, notable phytic acid and protease inhibitors , which reduce the nutritional value of the crop. Methods such as fermentation, soaking, germination, debranning, and autoclaving are used to combat the antinutritional properties of the cowpea by increasing the bioavailability of nutrients within the crop. Although little research has been conducted on

3416-526: The semi-arid Sudan Savannah zone of northern Nigeria. Annual rainfall is unpredictable, ranging from 500 mm to 1,300 mm per year during the June–;September period. Before construction of the dam, about 50,000 farmers in the Sokoto River floodplain practiced intensive recession farming, growing rice and sorghum in the wet season and vegetable crops such as onions, garlic and tomatoes in

3477-595: The size of suburban dacha or allotment garden plots or small city parks where the hectare would be too large. Many Russian dachas are 6 ares in size (in Russian, шесть соток ). The decare or dekare ( / ˈ d ɛ k ɑːr , - ɛər / ) is derived from deca and are , and is equal to 10 ares or 1000 square metres. It is used in Norway and in the former Ottoman areas of the Middle East and Bulgaria as

3538-503: The universally accepted V. unguiculata subspecies unguiculata classification, which is then commonly divided into four cultivar groups: unguiculata , biflora , sesquipedalis , and textilis. The classification of the wild relatives within V. unguiculata is more complicated, with over 20 different names having been used and between 3 and 10 subgroups described. The original subgroups of stenophylla , dekindtiana , and tenuis appear to be common in all taxonomic treatments, while

3599-404: The variations pubescens and protractor were raised to subspecies level by a 1993 characterisation. The first written reference of the word 'cowpea' appeared in 1798 in the United States. The name was most likely acquired due to their use as a fodder crop for cows. Black-eyed pea, a common name used for the unguiculata cultivar group, describes the presence of a distinctive black spot at

3660-419: Was Hoppin' John , which contained black-eyed peas cooked with rice and seasoned with pork. Over time, cowpeas became more universally accepted and now Hoppin' John is seen as a traditional Southern dish ritually served on New Year's Day. Cowpea seeds provide a rich source of proteins and food energy , as well as minerals and vitamins. This complements the mainly cereal diet in countries that grow cowpeas as

3721-584: Was delivered to 15,000 hectares by sprinklers and to 8,000 hectares by gravity. Sprinklers are expensive but make more efficient use of water if well maintained. After cost overruns, the irrigation project ended up as one of the most expensive per hectare in the world. Construction of the dam, with land leveling, clearing and canal construction destroyed valuable farmland and trees. The local farmers became landless peasants. Most received no compensation, or were given worthless land. Those that stayed were forced to grow unfamiliar crops such as wheat. During construction,

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