A reflection

It is easy to forget that water security is the necessary starting point to ensure food security. Yet it seems crazy (and evident) that so much more research needs to be done about the link between the two in Africa. Why is the utilisation of water, such a widely-used resource, still inefficient? The answer is simple; water is an ever-changing resource in terms of its availability and distribution, and the ways that people harness water are endless. There is no one link between food and water, but rather a complex web which I have tried to explore a small part of in this blog. One thing I have learnt throughout writing this blog is that the key to water efficiency is not just about the science, but also about creativity, which has potential to come from the bottom-up. However, many solutions and ideas need money, which there is an obvious lack of in developing regions. It is a vicious cycle that never ends; there is no development without adequate water and food resources, and on the other hand, there are few opportunities to better water and food security without development. Schulze (2011) claims that the impacts of climate change will be most felt through the medium of water. But on a more positive note, I have shared some encouraging examples of ideas that can be used in the future to make agricultural water use in Africa more sustainable, and I hope to continue to explore many more examples! 

Neglected and Under-used Crop Species (NUCS) – Crops of the future?

The agricultural systems of today seem to promote monoculture, or at least very low biodiversity of crops in a given area to reduce costs and maintenance (Chivenge et al. 2015).  There has been a decline in ‘traditional’ crops in Africa and an increase in their genetic erosion due to their replacement by major crops and due to the ignorance of NUCS in research and conservation (Dansi et al. 2012). However, research has shown that NUCS have the potential to address the current food security insecurity issues in Sub-Saharan Africa due to their high adaptability to low input agricultural systems as well as high nutritional values. 

There is currently no agreed definition as to what NUCS are, but Chivenge et al. (2015) have defined them as ‘crops that have not been previously classified as major crops, have previously been under-researched, currently occupy low levels of utilisation and are mainly confined to smallholder farming areas’ (Chivenge et al. 2015: 5688). NUCS were more important to subsistence farmers in the past and were grown as part of their diet or as a back up or alternative when the main crop failed, yet there is little written information regarding NUCS as information is trapped in indigenous knowledge systems (Nyadanu et al. 2016). Now, NUCS have been replaced by major staple crops that are in high demand, which are not that well-adapted to local conditions.  Promoting  the growth of NUCS and hence agro-biodiversity is vital so that agricultural systems can grow to become more climate change resilient by improving ‘nutrient cycling, carbon sequestration, soil erosion control, reduction of greenhouse gas emissions and control of hydrological processes’, and hence improve food security (Chivenge et al. 2015: 5686).  Sub-Saharan Africa’s development agenda consists of improving agricultural productivity, yet the plans and strategies being implemented are only concentrated on a small variety of crops.

NUCS include: 

• Sweet potatoes
• Wild melon
• Taro
• Bambara groundnut
• Wild mustard

These crops, as well as other NUCS are tolerant to biotic and abiotic stresses, including drought, and require minimal inputs, relative to other major crops. A plant has the ability to survive droughts if they have a short growing season, which means that they can finish their growth cycle before conditions of water stress are felt. Drought tolerance also occurs if water loss from the plant is reduced whilst root uptake is maintained. Water loss can be minimized through reducing plant height, leaf area and the number of leaves (Mitchell et al. 1998).  For example, wild watermelon, native to southern Africa, is believed to be drought tolerant as they maintain their photosynthetic mechanisms even when there is a lack of water (Miyake and Yokota 2000). Not only was it traditionally cultivated due to its drought resistance, but also due to its nutritional benefits and wider uses. Watermelon rind can be used in pickles, can be a source of pectin and the seeds are high in protein.

Watermelon growing in the Sahara (Source)

It is a shame that the expectations of today’s agricultural supply systems force farmers to reduce their agro-biodiversity without regards to indigenous lifestyles and nutritional values. The promotion of NUCS can only be successful if there is a greater respect for indigenous knowledge and the participation of local communities in agricultural strategic planning.

Chivenge et al. (2015) and Dansi et al. (2016) suggest that there needs to be an increase in the research on NUCS which will enable them to be promoted in the future, but I think that the lack of scientific knowledge is not the only limiting factor to the widespread growth of NUCS. Personally, I feel that the value of NUCS needs to be communicated to farmers better, who are more concerned about fulfilling the demand of external markets in order to make more profits. Nyadanu et al. (2016) claim that value can be added to these crops by conveying their medicinal uses, religious associations and traditional uses, and in many instances, women are mostly associated with cultivating NUCS as they have many household uses. So women may be the target when attempting to create a strong value chain for NUCS.

Water-harvesting: Faanya-ju terracing

Given that 70% of the African population is supposedly dependent on agriculture to sustain their livelihoods, it would seem that the African terrain is well suited for growing various crops. However, my previous blogs highlight that the potential for farming varies spatially – and this must mean that the difficulties and sustainability of farming must also vary amongst the 70% who are part of the agricultural sector. Nevertheless, families that have been farming have been doing so for generations, and traditional agricultural methods have been developed overtime to overcome and adapt to the obstacles and challenges presented by the African landscape. However, with climate change and changing water availability patterns, are these traditional methods adequate to withstand the pressures of the future, which include extreme flood and drought events? It is predicted that a 2 degree rise in the average global temperature could result in rainfall declining by up to 25% in many semi-arid regions (Schewe et al. 2013). Furthermore, in less than just 4 years time, 75 – 250 million people are predicted to suffer from water stress (AMCEN Secretariat). By 2020, rain-fed agriculture yields could be halved. These figures are not only worrying, but also highlight the urgency for farmers to change their practices. Do farmers have enough knowledge of basic water monitoring and management in order to adapt to the changes that are being predicted? We need to understand how farmers are currently addressing the situation.

Research also shows that 50-70% of the rainfall does not reach crops and instead either evaporates, or becomes run off (Rockstrom and Falkenmark 2015). My previous blog post touched upon conservation agriculture and the role of mulching as a solution to this. I want to now focus on techniques that are less technical in terms of the equipment needed (unlike irrigation or mulching), but are still very effective in terms of water efficiency. This leads me to draw attention to a successful water-harvesting example which is the Faanya-ju terraces in the Machakos district of Kenya. Terrace cultivation involves creating graduated terraces on natural slopes such as hills or mountains and planting crops on these steps (Encyclopaedia Britannica 2015).

Fanya-ju terraces (Source) 

Faanya-ju terraces are created by placing soil from trenches up slope to form bunds (banks) along a contour and repeating this process further upslope along more contour lines. Gradual erosion and redistribution of the soil eventually forms the terraces, as shown in Figure 1. Distance between each bund varies, however, they are generally 5-20 metres apart (UNEP). The unique spatial structure of the terraces including the bunds has the ability to control and direct water run-off where it is needed, so that water can be conserved within the soil, preventing dispersal and hence valuable water losses (Figure 2). This is where Faanya-ju got its name; it is the Kiswahili words for ‘throw it [soil] upwards’ (WOCAT 2016).

Figure 1: The development of the terraces overtime (Source) 

Figure 2: Diagram to show how the terraces store water (Source) 

In the Machakos District, 1000 km of new Faanya-ju terraces have been constructed each year since the 1980s. The National Soil Conservation Programme in Kenya trained over 500,000 farmers in conservation technologies, including faanya-ju farming. Now, 70% of the area practice terraced farming voluntarily, suggesting that there has been little or no resistance to this method by farmers (WOCAT 2016). Crop yields as a result of faanya-ju farming has reported to have increased by 50% which is a clear benefit to the farmers (UNEP). All this is evidence to support that the technique has generally been a success. Furthermore, beyond its obvious benefit to crop yields, stone terrace walls allow excess water to infiltrate between the stones and be redirected into nearby streams, improving the village water supply. The terraces have generally improved soil moisture and reduced erosion.

During the 2009 drought in the region, farms using faanya-ju terracing still yielded crops despite a lack of water (IIED). With droughts predicted to increase, there is a sense of hope that this can be a viable method that can be used in the future to withstand droughts. Nonetheless, the disadvantages of this method also need to be acknowledged. Faanya-ju farming can only be applied in very specific environments (Figure 3), such as where there are slopes, where annual rainfall exceeds 700 mm and where the soils are deep, meaning that it cannot be used as a method in the drier and flatter regions of Africa. The process is also very labour intensive and constant maintenance is required, especially if the bunds have not been stabilised and are prone to erosion (UNEP).  Terracing also reduces the area available to plant crops on due to the presence of the bunds, however, it ensures greater yield security and decreases the chances of a crop failure. Despite the downfalls of the method, I think that the example goes to show that water-harvesting methods devised for small-scale farmers can be very successful and implemented on a mass scale if it is carefully thought out and  farmers can easily realise the benefits. However,  before applying the technique elsewhere, more research needs to be done on suitability of the sites before implementing this type of farming. Needless to say, areas outside of the district have recognised the positive impacts that it is having on crop yields and water harvesting and are slowly adapting the practices to suit their terrains. Rockstrom and Falkenmark (2000) claim that water harvesting can raise crop yields and productivity from 1 tonne per hectare to 3-4 tonnes per hectare. If there are landscapes similar to the Machakos district of Kenya elsewhere in Africa, then this is a technique that should definitely be promoted further. This is proof that traditional water-harvesting methods can go a long way and complicated technologies aren't always needed!

Figure 3: The environmental conditions that are optimal for Faanya-ju terracing (Source)

Here is a good supplementary video that documents the reality of Faanya-ju terracing well and the positive impact that it has had on farmers in the region:

Increasing green water efficiency through conservation agriculture

In a previous blog post, I highlighted the need to focus agricultural activities in areas with high green water availability and low blue water needs. Much of eastern and southern Africa have relatively low green water use efficiencies of only 15-30% due to high rainwater runoff, large evaporative losses and poor soil water storage (TerAvest et al. 2015: 285). As green water is water that is stored in the soil, I wondered if unsustainable farming in parts of Africa has in fact led to decreases in green water availability through soil reductions in soil water capacity, and whether this can be controlled.

A study by Nyberg et al. (2012)  showed how land use changes from forest to agricultural land in Western Kenya has reduced infiltration rates, where median infiltration rates on agricultural land decreased by 15% compared to original infiltration rates in the forest. Not only is it essential to maintain soil infiltration so that plants can uptake water, but infiltration is also necessary for groundwater recharge. Intensive agricultural practices are partly to blame for the decline in infiltration capacities. For example, the moldboard plough has been a popular tool in agricultural practices in southern Africa, but intensive over-usage of the plough has led to soil degradation and increased run-off, reducing soil moisture and water infiltration (Thierfelder et al. 2013).  A reduction in the capacity of the soil to hold water reduces green water availability for crops, making it necessary to withdraw more water from blue water sources which can be unsustainable. 

When looking at what can be done to reduce erosion whilst still being agriculturally productive, I came across a concept that encourages and encompasses water efficiency, known as ‘conservation agriculture’. Conservation agriculture is a set of soil management practices, defined as ‘minimal soil disturbance, year-round ground cover, and crop rotations being promoted in a way to sustainably improve water-use efficiency, reduce soil erosion and boost crop production’ (TerAvest et al. 2015: 285). Parts of Australia, North America and South America have adopted conservation agriculture, albeit the agricultural context of farming is very different in these countries compared to Africa – that is, Africa has a less mechanised, smaller-scale agricultural system. However, based on the success of conservation agriculture in Australia and the Americas, international donor communities have encouraged the adoption of the approach in Africa (Thierfelder et al. 2013).  There are many practices that make up conservation agriculture, but I will focus on a practice that has directly impacted soil-water levels, known as residue retention, or mulching. Mulching involves using crop residues (dead or live, such as stalks and leaves) to increase ground cover, which lowers evaporation, and decreases erosion (Thierfelder et al. 2013).  Not only does mulching improve soil-water content and quality, but also maintains soil temperature throughout the night (Stauffer and Spuhler [no date]). Studies on maize growth in Africa generally showed that soil water infiltration improved when mulch was added to the maize fields (Brouder and Gomez-Macpherson 2014).

A groundnut farm in Malawi following conservation agriculture. Mulch in the form of corn stoves can be seen in between the rows (source). 

However, there is also controversy surrounding the potential for conservation agriculture in improving small-scale agriculture in Africa, and currently, its adoption in Africa has not been widespread, albeit, conservation agriculture practices have been increasing in Zambia, Malawi and Zimbabwe (Wall et al. 2013 cited in TerAvest et al. 2015). Whilst research has shown that conservation agriculture generally improves soil moisture, soil moisture content is essentially dependent on the soil type. And if soil type is not accounted for, conservation agriculture can have devastating impacts. For example, conservation agriculture can increase the risk of waterlogging if it is carried out on sandy granitic soils (Thierfelder and Wall 2009).  Academics have also ignored the different socio-economic contexts that constrain the adoption of conservation agriculture. I talked about mulching as a method to reduce soil degradation, but mulching requires crop residue, which farmers use for other purposes, such as for animal bedding, livestock food, construction (fencing and thatching), and as a source of fuel (Thierfelder et al. 2013). It is definitely not a resource that is available in abundance to small-scale farmers in areas where crop-livestock systems are common.  One solution I came across to address this issue is the use of inorganic mulches, such as plastic sheets, stone or shredded rubber, which can act as a replacement for organic mulch. Regardless, for the majority of farmers who are small-scale, inorganic mulching may not be affordable, and the implementation of inorganic mulch often requires machinery and additional knowledge, as the type and colour of inorganic mulch required is dependent on what is being grown. Inorganic mulch may be more effective in preventing evaporation but may not be the best for increasing infiltration.  I personally prefer the use of organic mulching as this makes the best use of the available resources and does not entail as much technical knowledge. Nonetheless, organic mulching can have its downfalls too. In addition to not there being enough crop residue for mulching, too much organic mulch can lead to rotting and encourage pests to accumulate causing crop damage. Furthermore, if carbon rich materials such as stalks are used, there will be competition between plants and decomposing microorganisms for nitrogen, which can also impair crop growth (Stauffer and Spuhler [no date]).

Even though I only touched upon a very small part of conservation agriculture, I believe it is not a solution on its own to address Africa’s soil degradation. I do not believe that conservation agriculture should be applied blindly wherever possible, as the effectiveness of conservation agriculture can evidently vary between different contexts. Farmers may also not be interested conservation agriculture given the risks associated with increased mulching, and if the associated risks cannot be mitigated to a level that gives farmers a sense of security, then it should not be forced upon small-holder farms. Conversation agriculture does however, hold one of the answers to reducing blue water usage if applied carefully and can be part of a wider solution to address inefficient agricultural water usage in Africa. 

Rwanda taking the lead?

Here's an article I found this week about Rwanda investing in a new solar powered irrigation scheme in efforts to adapt their agricultural practices to withstand droughts and become more climate resilient. This is a great step forward, not only because it is using a renewable energy source but also because it looks like it has been planned for the long-term, a change from the usual investments in typical short-term unsustainable solutions that we often see from African governments.

Source

The effects of drought beyond decreased yields

Check out this article I found on the Guardian published in April 2016, but still very relevant to the context of this blog, in terms of discussing the links between food and water. In academic papers we often see the statistical side of things, with the impacts of drought on crops being quantified by its effects on yields and prices. I like this article and thought I would share it as it delivers a more personal narrative of the wider implications that food insecurity, as a result of drought, can have on communities in Africa. The article talks about how a lack of food is affecting the education of many children and causing them to lose the energy and good health to study, resulting in rising school drop out rates. In addition to this, children are having to also drop out to help their families find food.  There is also an issue regarding gender here, as girls are often being forced into sex with no other choice in order to receive food. The effects of food insecurity in terms of climate change and changing hydrological variability are often overlooked, and the knock-on consequences of droughts need to be acknowledged more beyond statistics, and this article does exactly this!

Large-scale irrigation - not to be ignored!

I may not have praised large-scale irrigation schemes in my previous blogs, but the reality is that large-scale schemes are getting more and more popular in Africa. In the last ten years alone, more than 22 million ha of land in Africa has been leased out to large-scale land acquisitions for agricultural purposes (Johansson et al. 2016).  This has led to increased pressure on freshwater sources. With further population growth, industrialisation and urbanisation, there is intense competition for water with other water-intensive sectors such as the fishing and energy industries. However, the agricultural industry is still the sector that consumes the most water, using 70% of all global freshwater withdrawals (Steduto et al. 2012).

Water used in agriculture can be categorised as either blue water or green water. Green water is the water that is stored in soils and taken up by plants by evapotranspiration, whilst blue water is water that is extracted for agricultural production from surface or groundwater sources (Falkenmark and Rockstrom 2006).  On a global average, only one third of precipitation becomes runoff that discharges into surface water sources (e.g. rivers) and recharges groundwater sources. This is blue water. The remaining two thirds of precipitation enter the soil, which is the green water, and is constantly being returned into the atmosphere as water vapour (Hoff et al. 2010). The issue is that blue water can be taken from non-renewable sources as well as non-local sources in order to allow for agricultural production. This is unsustainable and taking water from non-local sources can reduce water availability downstream or elsewhere. According to Falkenmark and Molden (2008), increasing agriculture leading to increased water withdrawals has resulted in the 'closure' of a rising number of river basins.  A river basin is said to be 'closed' when 'committed outflows from a sub-basin ('including flows required to meet downstream allocations to meet societal needs, dilute pollution, meet environment flow needs including sustenance of estuarine and coastal ecosystems, flushing sediments and controlling saline intrusion') cannot be met for an entire year (Falkenmark and Molden 2008: 202), and currently, 1.2 billion people in the world are living in areas undergoing river closure. The whole concept of green and blue water can help us understand the additional amount of freshwater needed besides precipitation to enable agricultural production, which in turn will aid understanding of the extent that it is sustainable. 

Transnational agricultural investors have rushed to Africa for cheap land and labour costs, and have been welcome by African national governments in hopes that investment will spur agricultural modernisation. Land contracts do not specify any restrictions on water usage, so investors usually tend to choose the cheapest irrigation schemes which have very inefficient water uses.

Figure 1

Figure 1 shows a graph, taken from the paper written by Johansson et al. 2016, depicting the green and blue water requirements for different types of crops grown on 95% of the large-scale land acquisitions in Africa. The size of each plot (bubble) is dependent on the total water demand according to the national level for each crop (countries labelled on plot), with the darker grey area showing crops with relatively low water requirements, and the lighter grey area showing crops with relatively high water demand. The graph shows us that water demand for each crop varies by country, even if it is the same crop. For example, sugarcane grown in Madagascar has a higher water demand than sugarcane grown in Zimbabwe. Another example is in corn production, where corn grown in Egypt has a higher blue water demand than corn grown in Kenya. This is due to variations in temperature and rainfall between countries (Johansson et al. 2016). Where there are high temperatures and low rainfall rates, soil moisture content will be low, therefore green water availability will be low, requiring more blue water inputs. In theory, the solution to reducing water usage would be to grow crops where there is an abundance of green water (reducing the volume of blue water needed) and to choose crops that do not need as much water inputs, like corn. Albeit, in reality, the choices of crops grown are seldom made on the basis of how much water they require, and more to do with their prices and demand. This is where irrigation is necessary.

According to (Johansson et al. 2016), irrigation will double the yields for crops compared to solely rainfed management.  Sadly, as mentioned, many irrigation schemes using blue water on these large-scale plots are not efficient. As a result, some areas will face increased water pressure and scarcity if they continue to operative using the same irrigation methods.

Figure 2

Johnansson et al. 2016 identify what they call ‘blue water hotspots’, which are areas where more than 50% of the water demand is for blue water sources, as shown in Figure 2. The map on the left shows areas where more than 50% of the water demand can be met by precipitation. According to this data, 35% of all the area under contracts and investment would be blue water hotspots. Rather than unrealistically saying that large-scale irrigation needs to be prevented or that green water should be the only water input allowed for crop growth, a more feasible solution would be to increase irrigation (and hence blue water) efficiency.

I found the paper written by Johansson et al. particularly interesting as it differentiated between the types of water required in crop production to give a clear explanation as to why water demand varied spatially. The spatial variation in green and blue water demand is a key point to consider, as certain areas will be more adapted for sustainable irrigation than others. In a growing bid to increasing food security and meeting rising food demands, it is important that that suitable areas which require less blue water inputs are identified quickly, and investment is encouraged where blue water demands are low.