Chapters 5.56
5.56 -Sorghum in African Agriculture
Rhyss Oldacre, University of Guelph, Canada
Suggested citation for this chapter.
Oldacre,R. (2022) Sorghum in African Agriculture, In Farmpedia, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org
Background: Sorghum in African Crops
Sorghum is a crop believed to have been domesticated in Ethiopia roughly 5000 years ago (Hariprasanna & Patil, 2015). Today, it is the fifth most commonly grown grain crop worldwide (Sorghum Solutions, 2017). In recent years, globally roughly 58 million tons of sorghum is produced from 42 million hectares (FAOSTAT, 2001). Sorghum is a staple food for over 500 million people throughout the world (Djanaguiraman et al., 2018). While production takes place across the continent, 70% of production can be traced to Ethiopia, Nigeria, Sudan and Burkina Faso. This crop has a number of interesting features, however what causes it to stand out compared to other cereal crops, is its significant drought tolerance. This crop is low-maintenance and does well in dry, hot conditions. The crop is used to produce flour, syrup, animal feed, and is a staple ingredient in many local and regional beers. Another perk of this grain is that it is also gluten free (Agricultural Research Council, n.d.)
.Development and Physiology of Sorghum
Sorghum is known for its high degree of genetic diversity, including 43,000 accessions found in the USDA seedbank collection (Kimberly et al., 2013) and 42,000 accessions in ICRISAT in India as of 2019 (www.ICRISAT.org). The diversity of this grain is relevant, as it can directly result in traits which include virtually any quality of grain composition (Bean et al., 2018). It also results in a multitude of purposes spanning feed, food and fuel. What makes sorghum so successful as well, is that the genetic diversity within this grain may help facilitate breeders to develop it into an elite crop of drought tolerant cereals (Bean et al., 2018). Sorghum is mainly grown and produced in the semi-arid tropics in order to maintain food and nutritional security (Djanaguiraman et al., 2018).
Sorghum production falls within two broad regions, with the first being Africa and Asia, where it is produced at a small, subsistence level, with the grain being predominantly used for human consumption. Within the other region, mainly the United States and Mexico, production is at an industrial level, where yields are higher, and the grains are predominantly used for animal feed (Djanaguiraman et al., 2018). Within these regions, the average productivity of sorghum varies between 0.28 Mg ha-1 in Nigeria, to 4.4 Mg ha-1 in Argentina (FAOSTAT, 2014). However, due to the low-level use of inorganic fertilizer, as well as the low and/or non-existent use of pesticides, the average sorghum yield remains below at 1 Mg ha-1. Over the past twenty-five years, a steady increase in sorghum production throughout the semiarid tropics has been witnessed, thanks to better techniques.
Growing Conditions of Sorghum
Sorghum allows farmers in sub-Saharan Africa, the driest conditions of the continent, to produce viable harvests at a reasonably low cost. Sorghum has been designated as more heat resistant than wheat, and as a result of that, scientists have begun to develop even more temperature resilient varieties of the cereal in order to tackle the projected future global climate increase (Griggs, 2019). The optimal temperature to high producing sorghum varieties is > 25°C, some however have adapted to lower temperatures while still producing acceptable yields (FAOSTAT, 2019). When the mean daily temperature during growing seasons are > 20°C, early grain varieties take 90 to 110 days to mature, whereas if the daily mean temperature is <20°C, then there is an addition of 10 to 20 days for every 0.5°C below the daily mean. If grown at 10 to 15°C then the crop will take up to 250 days to grow and can only be used as a forage crop due to problems pertaining to seed set and the grain maturity (FAOSTAT, 2019).
Unlike maize, sorghum is relatively more drought tolerant, thanks to its extensive network of roots, ability to enter into dormant growth periods, effective control of evapotranspiration, and a stomata with a rapid recovery ability (FAOSTAT, 2019). It can scavenge for water at different depths. It requires water for 110 to 130 days, between 450 to 650 mm, depending on the climate (FAOSTAT, 2019). This crop is predominantly grown on degraded, shallow soils that possess high clay content, soil that, for example, would be completely unsuitable for maize, meaning it has the possibility to grow well for marginalized, smallholder farmers.
When first planting your sorghum, seeds can be placed in 30% salt concentrated water treatment, and seeds that float to the top should be removed – as those are diseased or suffer from insect damage (Agropedia, 2009). When sowing, there are three options: sow atop the ridge, in the furrow, or place on the sides of the ridge, and seeds should always be planted within 10-15 cm of each other (Agropedia, 2009). The planting should be timed so that when the sorghum flowers, it is not during the peak of summer heat, and for best yields, seed should be planted no deeper than 1 inch (Noble Research Institute, 1998). During germination, one shold be vigilant for wireworms, as the damage they cause could be exacerbated by unpreferable climate.
When harvesting, one should not attempt to harvest sorghum with >25% moisture. In order to keep yield loss low, harvesting should be conducted early with drying using mechanical support (Summer, 2017). For optimal results, sorghum can be harvested with sickle bar headers. When harvesting, only the grain head should be removed, with minimal leaves and stock being cut in the process. Use of a sieve to separate high moisture sorghum from low moisture quantities is beneficial (Summer 2017). The grain should be cleaned and stored in a dry area, ensuring a minimum aeration rate of 1/10 cfm/bu (Summer, 2017). While sorghum grain possess resistance to airflow due to smaller grain size, aeration is important to dry the grain.
Sorghum Nutritional Content
Per 100 g seed weight, sorghum has 329 calories. It has 10.4 g of protein per 100 g, higher than rice and most other millets, but lower than wheat and pearl millet (Hulse, Laing & Pearson, 1980). It is a small to reasonable source of B-group vitamins (riboflavin, thiamine and niacin), and a good source of carbohydrates at 72 g per 100 g. It is a low source of fat with 3.4 g (saturated, mono and poly), and has 6.7 g of fibre per 100 g (Hulse, Laing & Pearson, 1980). Depending on soil content, it can be a reasonable source of zinc, iron, magnesium and phosphorus. On average, is has a 3.3 mg quantity of iron, 16 mg of magnesium, and 289 mg of phosphorus per 100 g of seed (USDA, 2019). It is an overall great source of dietary fibre, low in fats, most of which are unsaturated, is a good high source of potassium, and is a moderate protein source, however, is low in the essential amino acid lysine. It is a low-cost gluten free option. Sorghum is used to make traditional African dishes such as ogi, a type of porridge, and tuwo, a thicker version (ICRISAT, 1982). It is also used to make Injera, a traditional and enjoyable sourdough flatbread. A traditional favourite is Kisra, a sorghum pancake, and finally, sorghum roti is a classic household dish, easy and quick to make (ICRISAT, 1982).
Sorghum as a Cash Crop for Smallholder Farmers
Sorghum is a highly versatile crop much like maize (corn), with a diversity of uses (MarketWatch, 2018). It is one of the most efficient crops when it comes to conversion of solar energy into chemical energy (MarketWatch, 2018). It is able to efficiently uses water, and alongside being known as a drought tolerant species, it is also considered environmentally friendly crop due to its versatile nature, water-efficiency, requires minimal fertilizer and pesticide use, and farmers are able to make use of every part of the crop (i.e., create baskets and mats from the stock)(Ogbonna, 2008). Depending upon the variety of sorghum, such as sweet, used to make syrups, alcohol and for biofuel/biomass, bicolor used for animal feed and forage, the crop takes on a separate value and purpose (Ratnavathi et al., 2016). The global demand for sorghum increases as it grows in status as a more cost-effective livestock feed, as well a necessary component of ethanol and biofuel (MarketWatch, 2018).
Additional Benefits to Women Farmers
The growth of sorghum and additional millets has shown additional benefits for female farmers. According to Farming First, which is the global coalition for sustainable agricultural development, women account for 60-80% of smallholder farmers (Farming First, 2018). The group has initiatives like “A friend that helps”; a local group of Kenyan women who harvest and sell sorghum to regional brewers, or even through CGIAR who initiates regular studies on female farmers. As maize, Kenya’s leading cash crop, has seen a recent decrease in production due to more frequent droughts, and increasing number of female smallholders are seeing benefits through the growth and cultivation of drought tolerant crops such as sorghum (Farming First, 2018).
Much like corn, sorghum is a multi-purpose, multi-potential crop. Currently, FAO is finding that many subsistence women farmers are bringing in liveable wages through the production and selling of sorghum, so much so that many local Kenyan farmers they have been working alongside have reported being able to buy a cow, as well as keep their children in school (FAO, 2018). Thanks to the flexibility and versatility of sorghum, many smallholder farmers are able to save money on synthetic fertilizers, as sorghum does not nearly require the same amount that maize does.
Critical Analysis
While this crop is an alluring one, as of recent, many farmers have been hesitant to adopt this drought tolerant crop, as striga, a parasitic weed, has begun to spread across Africa (Ouedraogo et al., 2017). As more aggressive drought has already begun to decrease the yields of many smallholder farmers, they are also witnessing their crops at risk due to the fast adapting striga. There are efforts to breed striga-resistant sorghum varieties (Hess et al., 1992). For smallholders, striga is a struggle as they need to optimize their already small yields for best product results. Many farmers also prefer to keep producing corn/maize as it has the most global market profit and value, and it is a staple crop in many African diets (Unganai & Kogan, 1998). Corn is another cereal crop but not well adapted to a drying climate, as it requires a large amount of water in order to produce a fulfilling yield; it is currently growon on 24% of African farmland (Unganai & Kogan, 1998). Much like striga parasitizes sorghum, however, many corn fields have seen grave loses due to borers, insects, pests and droughts. Consumer preference and market demand in Southern and Eastern Africa also favour corn over sorghum, leaving farmers more likely to plant the riskier corn crop, and worry about the losses later (FAOSTAT, 2019).
Practical Resources to get started and Helpful Links
Link to the sorghum portal at ICRISAT http://exploreit.icrisat.org/profile/Sorghum/193
Link to sorghum varieties released by ICRISAT https://www.icrisat.org/tag/sorghum-varieties/
Link to ordering seed from ICRISAT http://genebank.icrisat.org/
Link to an interesting study done about how to improve sorghum yields in Kenya https://www.hindawi.com/journals/aag/2015/861919/
Interesting articles done in the types, history and availability of sorghum https://www.sciencedirect.com/topics/food-science/sorghum
Article on conservation agriculture in Kenya and importance of sorghum crop http://www.fao.org/fao-stories/article/en/c/1100298/
Article on overall history and modern usage of sorghum https://www.sorghumcheckoff.com/all-about-sorghum
Video providing information and details on sorghum production https://www.youtube.com/watch?v=BmdM93OFpps
Comparison of value and versatility between corn and sorghum https://www.agriculture.com/crops/corn/consider-sorghum
Sorghum production and utilization as livestock feed https://www.youtube.com/watch?v=aDR1ju3MSHQ
Why sorghum could be beneficial to Africa https://www.youtube.com/watch?v=76SFpv0ZCTE
References
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