Old Crops Become New: Sweet Potato (Ipomoea batata) Part 2

in Issue 37 by

An Underutilised Tropical Root

By Santiago Juan

An Underutilized Root

Sweet potato is a plant grown for its tuberous roots in tropical, subtropical and warm-temperate regions. As mentioned in the last Belize Ag Report, issue 36, sweet potato is cultivated for food in more than 100 countries, sometimes as a staple food but usually as an alternative food. All varieties of sweet potato are a good source of vitamins and minerals. In East Africa, the sweet potato is known as “the protector of children” because it is often the only food that stands between a child’s survival and starvation. A fast-maturing perennial plant, it is grown mainly as an annual. The roots are adventitious, mostly located within the top 25 cm of the soil. Some of the roots produce elongated starch tubers that vary largely in shape, colour and texture depending on the variety. The flesh of the tubers can be white, yellow, orange or purple whereas their skin can be red, purple, brown or white. The stems are creeping slender vines, up to 4m long. The leaves are green or purplish, cordate, palmately veined, borne on long petioles. Sweet potato flowers are white or pale violet; the fruits are round, 1-4 seeded pods containing flattened seeds.

The livestock industry can benefit from sweet potato forage as a source of protein, about 15-30% in the dry matter, but the forage quality depends on the proportion of leaves and stems, the latter containing much less protein than the leaf. Lysine is the main limiting amino acid. Unlike legume forages, it does not contain notable quantities of anti-nutritional factors. The vines are separated from the roots after harvest and provide a nutritive and relished green feed for ruminants. It is a suitable protein supplement for animals receiving low quality forages. Sweet potato can be fed to dairy cows as a supplement to forages such as Guinea grass or sorghum. Sweet potato greens have been successfully fed to dairy cows, sheep, goats, pigs, and rabbits. The economic impact of this is tremendous as it can reduce the farmer’s dependability on high protein-based diets which farmers have to purchase.

I cannot overemphasize the immense potential of the sweet potato as it produces more edible energy on marginal land than any other major food crop. As well as this useful property, it can withstand adverse abiotic and biotic stresses and does not require intensive care. It therefore could potentially contribute to a sound industry in Belize as so many Belizeans are small-to-medium size land owners. An industry around this crop would not be difficult to establish. In difficult financial times in Belize the sweet potato could well be one of our saving crops. The immense industrial value for the extraction of starch and production of animal feed has yet to be explored in our communities. Thus the sweet potato has great potential for enhancing food and nutrition security in Belize. Sweet potato has failed to attract sufficient attention of agricultural researchers throughout the tropics, Belize being no exception to this statement. With greater attention and more collaborative research, there could be considerable improvements in selecting local cultivars and improving husbandry which, together, would allow it to fulfill a wide range of needs in these areas of the world.

The 1996 World Food Summit definition of food security was adopted to mean “A situation that exists when all people, at all times, have physical, social and economic access to sufficient, safe and nutritious food that meets their dietary needs and food preferences for an active and healthy life”. Based on that definition, sweet potato can fulfill all the aspects of the objectives adopted at that summit nearly 21 years ago, yet in Belize we still see the mass importation of low quality food distributed countrywide.

Added value for farmers comes from a variety of products and ingredients made from sweet potato food including flour, dried chips, juice, bread, noodles, sweets, pectin and leaf powder for smoothies. Other research can be carried out in the fields of liquors and anthocyanin pigments in the purple varieties for food colouring and cosmetic industry.   Fresh sweet potatoes are baked, boiled, or fried and used in numerous recipes: mashed, pancakes, dumplings, potato salads just to name a few. All the foods which we currently make with the “Irish potato” we can prepare with the sweet potato, without having to import millions of Belize dollars’ worth of potatoes every year. This would not only have tremendous impact on the daily lives of our farmers as additional sales but also to all Belizeans as the foreign exchange would not be needed for the importation of yet another staple.

The flour produced from sweet potatoes could be used in the meat industry as a binder for sausages and meat patties without having to import so much wheat that has many social problems associated with it: not only the monopoly of the wheat flour in the Belize market but also the fact that it is a GMO crop, sprayed with glyphosate that Belizeans have routinely said they would prefer not to have to eat because of the rising problems with gluten intolerance and other diseases that have been linked to glyphosate. The Belizean authorities have little, if any, control over the questionable agricultural husbandry behind the cultivation and handling of the imported wheat crop with herbicides, insecticides and fungicides Today we do not know what we are eating from the imported processed and unprocessed foods. We read in the press of all the uses of extremely toxic chemicals in the agricultural industry which we end up consuming. This is just another reason for us to focus on crops like the sweet potato which is local to us.

The International Potato Center (CIP) in Peru has the largest sweet potato gene bank in the world, with more than 6,500 wild, traditional and improved varieties. This diversity in the crop is a testament of its immense adaptability in the region.