Eating what we grow

We just celebrated Farmers Day in Ghana with its usual natural implications of eating what we grow in Ghana.  I write this article to give some perspectives on yam cultivation and consumption in Ghana. I was born and raised in a part of Ghana where yams were an occasional meal and depended on farmers in the Eastern or Ashanti regions.

So I grew up thinking yam was an occasional meal. Much later, I found out that there was so much yam being cultivated that every Ghanaian child could eat it all year round.

In secondary school, we ate yam once or twice a week but it was not enjoyed by everyone because rice was more readily available in the school. As I grew up, I wondered why potatoes became more available than yams. 

I tried to find out why, using the tools at my disposal: my students and my laboratories. I also asked lots of people questions about why not yam. The answers were universally the same: yam is tedious to deal with, rots easily and takes too long to prepare. But I also learnt that yam from our part of the world is much better than potato and rice. Yam is much healthier, with lower carbohydrate levels; so it is healthy for diabetics and those who need to lose or maintain their healthy weight. Yam also contains a lot of antioxidants which are good for retarding aging and reducing high blood pressure.

Comparing yam with other staples

We live in the hot tropics where our cells are subjected to what scientists call reactive oxygen species produced as a result of heat and other types of conditions. These tend to speed up cell death at rates that exceed the production of new cells.  But creation made sure that we are protected from this rapid cell death through the variety of foods we have near us. The high antioxidants in our tropical foods such as yam, cassava, plantain, sweet potatoes and cocoyam, protect us from these environmental damages. 

Similarly, nutritionally, yam has many advantages over preferred foods such as polished, imported rice. Yam contains substantial amounts of dietary fibre which helps reduce constipation and reduce cholesterol levels. It also contains calcium, phosphorus, iron, potassium which helps in controlling heart rate and blood pressure; and vitamins C, A and B complex (antioxidants) which help in managing cellular processes, fertility, eye and skin health.

Rice is a good alternative for energy and growth when we can’t produce enough carbohydrates. However, if you eat rice in the large quantities served in ‘check check’, fast food joints and in many homes while you have a sedentary lifestyle then you are looking for trouble. This is because the body changes all the calories it cannot use into fat and sugar and this can lead to cardiovascular diseases and diabetes.

Why are we eating more rice than yam?

Ghanaian farmers lose over one million tonnes of yam each year due to spoilage; and farming yam is also a tedious and laborious venture. These losses discourage the farmers from producing more or engaging in this type of farming. Recently, there was a ban on the export of Ghanaian yam to the USA. The reason was that the yams were rotten as a result of infection by fungi and bacteria on reaching US soil. 

Our research into yam shows that there is a wide range of fungal, bacterial and yeast infestation that opportunistically ferment it. That is why it is possible to sometimes smell alcohol in yam. 

There is a lot of interest to find out where infection starts. Is it in the seed? Is it in the soil? Is it due to the some insects? Or is it after harvesting and during transportation or even during marketing? 

It is recognised that organisms opportunistically enter the tubers through skin wounds during harvesting or transportation. Our studies have shown that the inner protective cover of the yam which is rich in antioxidants is able to limit infections even if the outer layer is damaged. It is also possible that the four sweet varieties of yam:‘pona’, ‘punjo’, ‘asana’ and ‘lareborkor’ may account for the substantial post-harvest loss of yam in Ghana due to their high sugar content. 

Post-harvest loss is a huge problem because it impoverishes farmers and the nation as a whole and is experienced in similar crops such as plantains, bananas, cocoyam, cassava and others. We, therefore, eat more rice than yam because rice is more available and does not spoil as easily and it is convenient to prepare for our more busy lifestyles.

But how do we turn this around so we can eat more yam which is better for our health and economy? We need to address the challenges farmers face and the dilemmas of consumers.

Cultivation

Currently, there are breeding programmes that aim to combine properties of the many yam varieties to come up with the most optimal breeds that address some of these issues. However, to make these new breeds acceptable, they need to continually engage consumers on matters of taste and convenience. 

The type of farming method used and the quality and amount of yam seeds available also affect the yield of the farmers. It is estimated that using mounds can produce about 3000 tubers of yam per acre whereas ridges yield twice the amount with 6000 tubers per acre.  

The cultivation of yam is not a job I would like to do, because it is too cumbersome and risky. Typically, the farmer digs a hole, breaks up the soil to fill the hole and make a mound. They then place the seed yam one third distance from the top in the mound. Each stand gets a stake for the vine to climb to access light and grow. The yams are harvested by digging manually in the mounds to collect the tubers. They are most often transported by head porters to the farmers’ homes. Given the continued use of such laborious methods, it is not surprising that school leavers do not heed the call of policy-makers for them to go into farming.  Likewise, I would not be surprised if Ghana does not have a single yam farm which has the size of a hundred hectares. The question is: What would it cost to develop appropriate technologies that make it efficient to plant and harvest yam? Would such technologies not make the farming and production of yam more attractive to the youth and encourage more farmers to increase productivity and hence increase availability of healthier sources of carbohydrates, reduce foreign currency used for food imports and increase the number of youth farming and rural development?

Furthermore, currently, parts of the tuber are used for planting through clonal propagation. Some farmers use agrochemicals to protect the material from bacterial and fungal decay before it germinates. However, while clonal propagation preserves the best attributes of a crop, it does not protect it from virus diseases. This leads to crop losses and low productivity yields from the high potential yields. High yields could be ensured using available techniques used to remove viruses from select parental stocks and these are multiplied through micro propagation methods to generate disease free seedlings.

Disease-free seedlings

Local seed entrepreneurship composed of technology businesses and nurseries focused on production and sale of disease-free seedlings could virtually double the yield of yam overnight. Seed entrepreneurship can enhance farm productivity, farmers’ output and earnings and reduce the cost of yam as food and create jobs for skilled, unskilled labour and graduates.

Moreover, inefficient farming methods and lack of or poor quality yam seeds are not the only challenges in increasing local demand for yam. Post-harvest losses and lack of value-adding processing limit the potential of the yam value chain in Ghana. For instance, many fungal diseases which cause yam to rot are opportunistic. That is, unwounded tubers are unlikely to be infected and rot. The wounding can occur during harvesting or transportation. What can be done about the handling and transportation of yams to reduce the damage and spoilage of tubers? Low level irradiation of yam tubers kills fungi on the surface to reduce rotting. Some exporters get Ghana Atomic Energy to irradiate their yam as protection during exportation but why can’t this technology be utilised more widely for local market produce?

Development and application of appropriate technologies along our agricultural value chain can enhance Ghana’s potential to reduce food prices, increase employment and incomes, reduce rapid urbanisation, increase rural development and offer better alternatives to intervene in lifestyle diseases while meeting the needs of the Ghanaian consumer of today. 

In our next article we will address the issue of food processing and its role in industrialisation and socio-economic development.

The Institute of Applied Science and Technology (IAST) at the University of Ghana was established to ensure that research outcomes are transferred to industry for national development. All disciplines required in the agricultural value chain are available on one single campus. 

The institute’s activities are, therefore, inspired in part by the university research and in part by what industry is already doing in the value chain and we contribute to enhance these industry interventions. 

The IAST plans to establish a food venture incubator which will train and also work with entrepreneurs, farmers and small scale industries and other actors in the value chain to increase productivity and value addition, enhance food security, create and maintain jobs and ultimately assist in improving Ghana’s GDP position.

The writer is a Professor of Biochemistry and heads the Institute of Applied Science and Technology (IAST) at the University of Ghana. He writes as part of the dissemination activities of the Centre for Sustainability and Enterprise Development (CSED) at University of Ghana Business School. 

Writer’s e-mail :  csed@ug.edu.gh