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Are you contemplating going into agriculture, but unsure of which direction to go? Is your goal to minimise risk while optimising yields and income from agriculture with less capital? Are you also thinking of a crop you can sell and feed yourself and family with? Think of sweet potato!

Why sweet potato?
Sweet potato, botanically called ipomoea batatas, is a starch-containing and tasty root vegetable, having a thin, brown, purple or yellow skin on the outside with coloured flesh inside, most commonly orange, white and yellow.Nutritional value of sweet potato includes being a rich source of fibre as well as containing a good array of vitamins and minerals, such as iron, calcium and selenium. One of the key nutritional benefits of sweet potato is that they are high in an antioxidant known as beta-carotene, which converts to vitamin A once consumed. Hence the crop is potential tool in the battle against micro-nutrients deficiency among millions of Nigerian children and women.

There is evidence that eating a healthy diet can reduce the risk of cancer. Studies have suggested that the antioxidants in the peel of sweet potatoes and purple sweet potato in particular, may help reduce this oxidation process, thereby reducing the risk of cancer.A study in Asia also found that diets high in vitamin-A vegetables, including sweet potato leaves, may provide potential protection from lung cancer.

Apart from being a staple crop, sweet potato is an important source of raw materials for the manufacture of starch, glucose and ethanol, and can also be used as a substitute for wheat flour in bread, as Nigeria uses cassava flour.Cultivating sweet potato profitably requires loamy soil or good soil texture, adequate land clearing and preparation, appropriate plant population per hectare, application of manure or fertiliser if soil fertility is low and effective weed and pest control.Additionally, a marketing plan should be prepared and implemented. Research must be done on where, when and how much to sell the produce at harvest.

Land clearing and preparation
SWEET potato yields well if land is well tilled, prepared and oxygenated. Clearing the land requires cutting, packing and threshing bushes. This could be done mechanically or manually. After clearing, the land should be ploughed, harrowed and ridged. Sweet potato thrives on ridges than on flat land.

Ploughing, harrowing, ridging and boom-spraying with herbicides of one hectare of land cost about N45,000. With this, the land would be adequately prepared mechanically.Similarly, weed control starts from land preparation. Compatible pre-emergence (application before weeds sprouting) herbicides are always applied on the land while harrowing and ridging. If handled well at this stage, there might be no need to weed the farm, for sweet potato is a cover crop that suppresses weeds if recommended plant density is observed.Weed infestations, experts at the Weeds Management Project of the International Institute of Tropical Agriculture (IITA), Ibadan, have said, could reduce harvest by 50% or more if infestation is not prevented and well managed.

Planting materials/population per hectare
SWEET potato planting materials are about the cheapest of all farm inputs. Vines could be obtained from existing farms, or bought at ridiculously cheap price. Vines are cut into smaller length of about 25cm and are buried on well prepared ridges at the outset of rainfalls in March or April. The cost of vines per hectare is between zero naira and N10,000. Zero naira because a farmer could get vines free of charge from other potato farmers.

However, improved varieties, especially bio-fortified ones, by research institutes, could be a bit more expensive at first procurement.The number of vines planted also determines the cost of weed control and yield. If the farm is adequately populated, yield would be maximised, weed would be minimised and cost would be moderate.

A study conducted by J.T. Ambe in Cameroon using three improved sweet potato varieties recently revealed that a density of 20,000 plants per hectare gave the highest mean tuber yield of 29.6 metric tonnes per hectare, while 10, 000 plants per hectare, the researcher said, recorded the greatest weed infestation and severity, which decreased yields to 17 tonnes per hectare. He recommends a density of 20,000 plants per hectare for maximum yields, low weed infestation and high returns on investments.

Economics of sweet potato 
One Abdul Kadir, a potato farmer in Afon, Kwara State, said a medium-size bag of the crop (about 80kgs) is sold between N3,000 and N6,000, depending on the time of harvest. Between March and June, when most farmers always start planting, a bag of sweet potato would sell for N5,000 on the average, but could reduce to as low as N3,000 between September and November.

Average of 250 medium size bags of sweet potatoes could be harvested on one hectare of land. He said with this, between N750,000 and N1.5 million could be made from one hectare of farmland in three months.However, deepening production of the crop is still very constrained, for little or nothing has been done to explore industrial uses of sweet potatoes in Nigeria, making farmers to still struggle with subsistence production.

Large scale production, however, should be done with adequate marketing strategy to avoid oversupply. The shelf life of sweet potato is short after harvest, although very much longer than cassava. As of today, there is no single sweet potato off-taker or industrial processor in Nigeria, making it difficult to up-scale its production.

Selling sweet potato should be planned adequately even before production. In the rainy periods covering August to November, most farmers harvest their crops. Hence, there is always a price crisis, because the supply tends to overwhelm the demand, at least in the producing neighbourhoods.
Extending marking plans to urban centres where there is high population density would always be reasonable and economical in these periods. So, penetrating urban markets should be an integral part of the business plan.

However, large-scale production in the dry season through irrigation would make more economic senses, with little stress of marketing.One very good thing about agricultural products is that if they are produced fresh off-season, they become hotcakes, naturally obeying the law of demand and supply. A monopoly of supply off-season would command good prices and would eliminate the stress and cost associated with excessive marketing.

Source: The Guardian