SWEET SIDE OF SWEET POTATO part2

REGIONAL DISTRIBUTION OF SWEET POTATOE IN NIGERIA

The distribution of sweet potatoes in Nigeria is not to the precise via geo-reference data. (Huachho and Hijmans, 2000) estimated a global distribution of areas solely devoted for sweet potato cultivation by assigning national data from various sources to sub-nation unit.

 The tuber and Root Information System (TRIS) developed by the International Institute of Tropical Agriculture (IITA) took a different approach for sweet potato and to an extent yams and cassava by modeling the physical parameters which estimates an ordinal suitability ranking for each crop across Africa. This simply means rankings or the distribution of sweet potato is determined by a combination of factors that includes, annual rainfall, soil classes, temperature, length of growing period etc.  Using this model in estimating sweet potato distribution in Nigeria shows that highest cultivation of sweet potato occurs in the ‘”Middle Belt” region (Tewe et. al., 2001) while a broad range of the country is taken into consideration approximately 7⁰ to 11⁰ north.

 This indicated that sweet potato traditionally been grown in a few restricted areas of the central and southeastern zones which might have been centers of concentration in time past. In recent years sweet potato has become a widespread crop in Nigeria.

Preliminary surveys  shows an estimate indicating average yields in Nigeria to be 7 tons per hectare  in the Southeast while there is a reduction of about  3 tons per hectare  towards the North. This reduction does not hold everywhere in the North since there is an exception towards the centrally placed Plateau and Bauchi states. At these places the yields are usually about 7 – 8 tons per hectare. (Tewe et. al., 2001).  Several states of the south and central regions of Nigeria (Oyo, Benue, Plateau, Taraba, Kogi and Cross Rivers) are also areas where sweet potato is widely grown (Eneji et. al., 1997). While in the North, cultivation of sweet potato extends by their estimates far north towards Kaduna and Bauchi states.

In Nigeria, sweet potato farming is determined by largely on season rain. The best crop yields generally occurs in areas of 750 milliters(mm) to 1,000(mm) annual precipitation, with at least 500militeres of rain during the growing season (Tewe et. al., 2001).

In Nigeria planting takes place from February through July in the central to southern regions where rainfall is most plentiful. Still, in the central and northern regions of the country, planting along river banks or in swampy area can prolong the season and permit planting by September to December.

NUTRITIONAL CONTENT OF SWEET POTATO
(100g)(3.50z)
Energy:               37kJ(90kcal)
Carbohydrates: 207g
Starch: 705g
Sugars:     65g
Dietary fiber:      33g
Fat:     0.15g
Protein:   20g

VITAMINS PRESENT IN 100g(3.5oz)
Vitamin A equivalent:   961ug
Thiamine:   0.11mg
Ribolavin(B2):  0.11mg
Nacin(B3):   15mg
VitaminB6:   0.29mg
Folate(B9):   6ug
Vitamin C:  196mg
VitaminE:  0.71mg

MINERALS PRESENT IN 100g(3.50z)
Calcium : 38mg
Iron: 0.69mg
Magnesuim: 27mg
Manganese: 0.5mg
Phosphorus: 54mg
Potassium: 475mg
Sodium: 36mg
Zinc 0.32
Source: Wikipedia

Beside simple starch, raw sweet potatoes are rich in complex carbohydrate, dietary fiber and beta carotene(beta-carotene is a Provitamin A carotenoid). There is also a moderate content of other micronutrient including vitaminB5, vitaminB6 and Manganese etc. Interestingly when cooked by baking there is always a slight change in the variables of these micronutrient, example is the increase in density of vitamin C.

Sweet potato cultivars with dark orange flesh have more beta-carotene than those with light-colored flesh. This type of potato cultivar is being encouraged in Africa where Vitamin A deficiency is a serious problem. A 2012 study of 10,000 households in Uganda found that children eating beta-carotene enriched sweet potatoes suffered less vitamin A deficiency than those not consuming as much beta carotene.