Solar drying technology to Africa's rescue on the challenges in post-harvest handling of agro produce.

Africa mainly lies between the Tropic of Cancer and the Tropic of Capricorn. By this intertropical location, the continent has high precipitation intensities.

With the equator running through, it is the most tropical continent; with hot and warm climates dominating. (https://en.wikipedia.org/wiki/Climate of Africa)

The continent is also endowed with a vast expanse of land covering 29.7 square kilometres, with more than half still uncultivated. and together with a climate favourable for agricultural activities (World Population Review, 2014); a majority of it; especially the Sub-Saharan region is predominantly agro-based.

However, agriculture in Africa is not only characterised by traditional farming methods (Garrity et al., 2012) but also by poor and ineffective post-harvest handling methods especially in drying.

For centuries, direct sun drying has been the commonest way of drying foods in Africa. It is a cheap method of drying produce – sunlight is free and the only costs involved are drying mats or platforms, and cutting equipment.

However, direct sun-drying has some disadvantages: the temperature of the heat from the sun can not be controlled, leading to over-dried or under-dried foods. The weather is not always sunny and the crops are exposed to dust, insects and off-field pests like birds and livestock (Ismaila Senghore,2008), while some produce is lost into the soil or bush at the site of drying.

Therefore, these lead to very heavy losses. Uganda alone loses 20 - 30% of her cereals, 40-50% of her root crops and 30-50% of her fruits and vegetables annually (UNDP, 2015). Poor postharvest handling also leads to low produce quality, with problems such as mycotoxin contamination (Makerere University et.al, 2014).

There is therefore widespread food insecurity in the continent, as there are currently over 233 million malnourished people with the number expected to rise by about 132 million by 2050 (AGRA,2014), since agriculture is the main source of food.

With a causal relationship existing between malnutrition and productivity, malnutrition has adverse effects on labour productivity, the health of children and ultimately the economy (Kariuki, 2011). According to Diao et.al (2007), inadequate nutrition leads to a reduction in the growth of the Gross Domestic Product (GDP) per capita ranging from 0.16 to 4.0%.

The value added per worker in the agricultural sector is low in most African

countries. The average value added per worker for 34 sub-Saharan African countries stood at USD 318 compared to the world average of USD 1000 in 2008 (Rosen and Shapouri, 2012; AGRA, 2014).

According to FAO (2012), the countries with low value added per worker in

agriculture include Eritrea, Zimbabwe, Burundi, Zimbabwe, Malawi, Congo Democratic Republic, Madagascar, Lesotho, Uganda, Ethiopia, Zambia, Mozambique, Guinea, Senegal, Tanzania, Angola, Kenya, Gambia, Togo, Comoros and others.

The low productivity of agriculture accounts for the majority of rural Africans subsisting on less than 1 United States Dollar (USD) per day (Rosen and Shapouri, 2012).

Solar drying has the potential to reduce the losses in post-harvest handling by 98% (Isaac Ndyamuhaki, 2022). The produce is dried on mesh trays inside a chamber covered by a polycarbonate sheet (Seregio Naturinda, 2022); the chamber is heated by heat generated by a black sheet of metal placed at the base by a process called black body radiation (Alex Bwambale, 2023).

Therefore, the produce is conveniently dried; free from contamination from the dust and insects, and spoilage from bad weather (sudden rains). The method is time and labour-saving since a farmer can do other activities as the produce is being dried and does not necessarily require a lot of people to operate. (Gift Bukanza, 2022).

The Natural Convection Solar Dryer (N.C.S.D) exhibited at the Science, Technology, Engineering, Agriculture and Mathematics (S.T.E.A.M) festival, 2023 at Kymabogo University dried at temperatures ranging between 60 and 70 degrees Celsius favourable to conserve the nutritive value of most produce. It also had a drying efficiency of 74.6%. (Kyambogo University STEAM festival,2023).

With a variety of solar dryer types, solar drying technology can be applied in drying different types of food crops (Calvin Omonuk,2023), leveraging the abundant sunshine in the continent. Solar dryers can also be hybridized and hence be used in commercial agriculture.

With all these said, solar drying technology has a great prospect of filling the gap in Africa's food production chain by eliminating the challenges faced in pot harvest handling and drying in particular.

Solar drying can facilitate a reduction in post-harvest losses; fostering food security and reducing hunger (SDG 2); using a clean, affordable and environmentally friendly form of energy (SDG 7).

This also increases the household income levels among farmers, thereby reducing poverty and improving the livelihoods on the continent (SDG 1).

Solar drying technology; is not only coming in handy to the rescue of the continent in proper post-harvest handling but is also a vehicle in the quest for sustainable development.

Jonathan Okello,2023 - Volunteer in charge of Research and Innovation at Asili Kwanza Uganda and volunteer internship tutor at Swiftia Development LTD .