**Eliminating Hunger: Yam for Improved Income and Food Security in West Africa**

**Beatrice Aighewi, Norbert Maroya, Robert Asiedu, Djana Mignouna, Morufat Balogun and P. Lava Kumar**

#### **1. Introduction**

Yam is a monocotyledonous tuber crop in the family Dioscoreaceae. The genus includes more than 600 species worldwide (Mondo et al. 2020), but only a few are cultivated. *Dioscorea rotundata* is the most valuable and widely cultivated species in West Africa, followed by *D. alata*. *D. cayenensis, D. dumetorum, and D. esculenta*, which are also cultivated in limited quantities in the region. Yam is a crop of great value in many communities in West Africa, and it is mainly cultivated for its underground tubers, although some species also produce aerial tubers. The crop has the highest value of the aggregate production compared to other crops in West Africa (Elbehri 2013; Hollinger and Staatz 2015), with an apparent per capita consumption that increased fastest in major producing countries of Ghana and Nigeria over the period 1980–82 to 2007–09 (Hollinger and Staatz 2015). While some yam species are important as food, others provide useful pharmaceutical products (Price et al. 2016; Tohda et al. 2017). Diosgenin and dioscorin are compounds isolated from yam and used in the pharmaceutical industry (Obidiegwu et al. 2020). However, some yam species are not edible due to poisonous substances (Dave et al. 2020; Joob and Wiwanitkit 2014; Kyung-Sik and Taek Heo 2015; Yoon et al. 2019).

Yam is grown as an annual with a duration from planting to harvest ranging from 8 to 12 months, depending on the agroecological conditions. Varieties in the forest region typically have a longer crop duration due to the longer rainy season than crops in the savanna. About 74.9 million tons of yam tubers are produced annually in the world on about 8.9 million hectares of land with an average yield of 8.5 t/ha (FAOSTAT 2021). Africa contributes 97.8% to world production, and Benin, Côte d'Ivoire, Ghana, Nigeria, and Togo account for 93.9% of world production (FAOSTAT 2021). Nigeria alone produces 66.9% of global production. Yam is the fourth most utilized root and tuber crop globally after potato (*Solanum* spp.), cassava (*Manihot esculenta*), and sweetpotato (*Ipomoea* spp.), and it is the second in West Africa after cassava (Lev and Shriver 1998).

Where yam is produced, it is a significant food source and cash crop, thus combating malnutrition, food insecurity, and poverty (Obidiegwu et al. 2020). In Nigeria and Ghana, 31.8% and 26.2% of the population depend on yam for food and income security. Yam tubers have better nutritional attributes than other root crops (Shajeela et al. 2011). The tubers are a good source of essential dietary supplements such as protein and well balanced essential amino acids (Baah et al. 2009). Even where yam is not a significant crop in some parts of Africa, it is considered a famine food for small and marginal rural families and forest-dwelling communities during periods of food scarcity (Ngo et al. 2015). In West Africa, yam is most preferred when processed fresh. It is mainly consumed boiled in sauce or soup (using pieces directly from the tuber or frozen chips from a supermarket), made into a dough by pounding boiled tuber pieces or reconstituting from flour (as instant pounded yam or *amala*), roasted, or fried.

Yam is often referred to as the "king of crops" in West Africa, and it is essential in the socio-cultural life of the population. It is used in ceremonies related to fertility and marriages, cultural rites of passage, thanksgiving, petitions, and annual festivals held to celebrate its harvest (Obidiegwu and Akpabio 2017; Nweke 2016). Poor seed and ware yam storage systems cause seasonality in the price and quality of available yams. Surplus during peak production season leads to price 'crashes', affecting farmers, while scarcity at other times causes a lack of affordability by consumers and undernutrition. Cropping of yam, especially seed, throughout the year therefore contributes immensely to the regional requirement for food and income.

#### **2. Trends and Systems of Yam Production**

A 70 percent increase in global food production is required to feed an additional 2.3 billion people by 2050 (FAOSTAT 2021), while food production from developing countries should almost double. Yam production in West Africa increased from 8.3 million tonnes in 1961 to 74.2 million tonnes in 2019. Figure 1 shows a decline in the average world yield to a present average of 8.5 t/ha, although yam has a potential of 40 to 50 t/ha (Adewumi et al. 2022; FAOSTAT 2021). The increase in production is due to an expansion of the area cultivated (Frossard et al. 2017). However, low productivity in most production systems results from poor quality of soils and inputs, accompanied by little or no application of improved agronomic practices (limited weeding, low planting density, persistent virus infections, no pest and disease management). Although there are improved and released varieties in major producing countries such as Nigeria and Ghana, local landraces still dominate farmers' varieties mainly due to challenges associated with large-scale multiplication

of seed to meet demand. Smallholder farmers who constitute the most producers mainly cultivate yam in the richest soils available to them. As fertility reduces, they use the land for other crops while yam cultivation is moved to more fertile soils. However, with an increase in population and pressure on agricultural land, the availability of fertile land is reducing. Therefore, marginal soils and non-traditional yam lands are put under cultivation to obtain the same yields or less.

**Figure 1.** Trends in yam production and yields in West Africa, 1961–2019. Source: (FAOSTAT 2021).

Traditionally, farmers use whole tubers or large setts (sliced portions of tubers) of 200 to 500 g or more as planting materials (seeds) and plant in mounds prepared using topsoil. Most yam farmers grow the crop without inputs such as fertilizer or undertake crop management practices to control pests and diseases (Mignouna et al. 2015). It is frequently intercropped, but sole crops are also common in West Africa. At harvest, farmers sort small- to medium-sized tubers (200 g to 1 kg) for reuse as seeds, while large-sized tubers (>1 kg) are used as food. They are stored and eaten piecemeal or sold in markets when cash is needed. The seed-sized tubers are stored to break dormancy before planting in the next cropping season, or they are planted in newly prepared fields where they will be dormant until the start of the rainy season three to four months later.
