Future crop yields

My mini-series looking at how the use of 'water-efficient' and 'water-suitable' or 'regionally-appropriate' crops mostly focused on the present situation. However, the future situation is even more important to consider. 

Climate change will considerably impact the availability of global water supplies, both above and below surface (Taylor et al., 2013). It is estimated that intense climatic extremes, such as flooding and droughts, will intensify, with rainfall becoming more varied (Taylor et al., 2013). As large areas of farmland in Africa depend on rain-fed irrigation, the impacts of rain-fed agriculture will be most significant. 

So, an assessments of the impacts need to be fully explored and understood, especially with regards to food security. A recently published article by Guan (et al., 2015) looked into the future variability of rainfall on crop yields in West Africa. West Africa is a region where 95% of farmland relies on rain-fed irrigation, so understanding if crop yield can be maintained at existing demands into the future is uncertain. Furthermore, future climate models predict that West Africa will begin to experience complex changes to seasonal rainfall (Biasutti, 2012; Monrie et al., 2012). 

Food security and stable income generation are important (Source)

The article uses projected changes in rainfall at 35 stations across West Africa predicted in CMIP5 (Guan et al., 2015). These rainfall levels are integrated into two crop models, APSIM and SARRA-H, which have been independently validated and calibrated with observed crop yields (Sultan et al., 2014). Sorghum is used as a study crop as it is highly prevalent across West African farms as a staple cereal crop which is highly efficient, drought resistant and flexible (Wholegrains Council, 2013). Due to sorghum's prevalence, the variation of yields was modelled with future rainfall estimates.

Guan's (et al., 2015) results showed that variation in crop yields was mostly a function of total annual rainfall. The greatest variations in yields were found at high and low mean annual precipitation (MAP). Higher MAP shows yield decreasing for APSIM sorghum yields, whereas SARRA-H yields respond with little response - reflecting the nitrogen sensitivity of the model (Sultan et al., 2014). At lower yields, both models suggest sorghum yield benefits more from intensity increases and are more sensitive to frequency or seasonal length variations (Guan et al., 2015). Furthermore, the delay of monsoonal onset may also negatively impact overall yields. 

In general, the results of the study show that changes in rainfall will have an impact on crop yields; however the exact changes in crop yield will depend on how rainfall intensity, frequency and seasonality changes are not fully known and designing of crop schemes or adaptations should seriously consider future variation in rainfall (Guan et al., 2015).

Yields and food security could be put at risk. In a region where droughts can quickly lead to widespread famine, mitigation strategies need to be considered to reduce the impact of yield losses and food insecurity.

The UN's Food and Agricultural Organisation (FAO) have begun looking at these issues surrounding agriculture in Africa and what more that can be done to mitigate loss of food from farms to home. According to a report released by the FAO, World Food Programme (WFP) and the International Fund for Agricultural Development (IFAD), 1.3 billion tonnes of food goes to waste every year (FAO, 2013). Reportedly, this volume of food could be used to feed 2 billion people. 

A $2.7 million pilot programme was run in Uganda, Burkina Faso and Democratic Republic of Congo (DRC) to look at ways of reducing waste during "harvesting, processing, transportation and storage as a result of inadequate infrastructure or lack of skills and technology" (FAO, 2013). Critical points of loss in supply chains were looked at with solutions tested and provided. The project focused on reducing losses from grains and pulses which make up many staple foods across the region. Sub-Saharan grain losses are potentially worth $4 billion a year (FAO, 2013). 

Almost a year after the initiative began, the FAO, IFAD and WFP have rolled the initiative, now called the Global Community of Practice, globally (UN, 2014).

The importance of understanding the impacts and risks of rainfall variation on food production and yields is paramount, especially when considering an ever increasing global population. However, international efforts are being made to reduce and mitigate against inefficiencies in food production, which hopefully can provide populations with enough food whilst the small issue of global warming is fixed!

Don't blame the tools #5: Tomatoes

This mini-series in my blog is dedicated to looking at how the use of 'water-efficient' and 'water-suitable' or 'regionally-appropriate' crops used can increase food security across Africa. 

A core staple cash-crop across most of the world is the humble tomato. Tomatoes are the base for many dishes across the world, but are not part of many staple dishes. For example, my recent trip to Uganda featured little in the way of tomatoes from what I can remember, other than the addition of Ketchup I added to a meal or two. During the dry seasons, however, (which varies depending on where you lie on the ITCZ) tomatoes shoot up in value.

Tomatoes for sale (Source)

There is significant value in tomatoes. According to one website, with investment capital of US$460, you could sell your produce for a minimum of US$2,000. However there is a down side. Although tomatoes are suited to dry soils, they require vast quantities of water, so irrigation is key. The Department for Agriculture, Forestry and Fisheries (DAFF) in South Africa explains that over an 12 week growing period, tomato plants must receive a constant supply of water totalling almost 400mm of water (DAFF, 2011). Referring back to an earlier post on MacDonald's (et al., 2012) assessment of groundwater reserves across Africa, recharge rates (>100mm/yr) are only sufficient in Sub-Saharan regions of the continent, suggesting groundwater-reliant tomato production is only sustainable for Sub-Saharan countries. An NGO project called 'Tomato Jos' has been set up to help the sustainable and profitable production of tomatoes in West Africa. Tomato Jos have begun installing a network of very expensive, efficient drip irrigation lines to supply water for crops from pumped river or groundwater resources, consuming 50% less water and improving yields by 40% (Tomato Jos, 2014)

Unless you live near a body of water or in select parts of Sub-Saharan Africa, you cannot sustainable grow tomatoes. Furthermore, tomatoes cannot be intercropped with other crops, must be 18 inches apart, and is very prone to diseases and fungi such as blight and Fusarium wilt (Fortuneofafrica.com, 2015; DAFF, 2011). 

A good example of the issues tomato farmers face are presented in a report undertaken by the FAO in Egypt. 3% of Egypt's landmass is cultivated and 3% of cultivated land is used for tomato production (EI-Sherif, 1997). Tomato losses are high however due to the "leaf curl virus, early and late blight, and nematodes" with nematodes affecting approximately 25% of tomato plants in fields (EI-Sherif, 1997).

Hypothetically, let's get past the high water consumption, potential infections and diseases, and large land size required. In Mozambique, the International Fund for Agricultural Development-lead (IFAD) PAMA (Agricultural Markets Support) programme has helped rebuild the irrigation networks and implemented economic reforms to improve market access for small farmers to the private sector (IFAD, 2009). Tomatoes, as well as other cash crops have done well in this programme, providing access to supermarkets. However, transportation duration can vary through longer private-sector supply chains. Tomatoes are bought half green to prevent loss during transport (IFAD, 2009). Agro-processing industry networks have yet to be established within Mozambique, but would provide alternative market outlets for lower quality, excess or over-ripe tomatoes (IFAD, 2009). 

Tomatoes generally aren't that great. They require vast amounts of water, making them unsuitable for much of the continent, unless you are near a large body of surface water. Tomatoes are vulnerable to splitting, pests, disease and overcrowding. Mitigation against these issues can be expensive and require international help to provide access to markets and funds. Their water-suitability is limited to water-rich regions, but the potential financial benefits for farmers should not be ignored.

Don't blame the tools #4: Argan

This mini-series in my blog is dedicated to looking at how the use of 'water-efficient' and 'water-suitable' or 'regionally-appropriate' crops used can increase food security across Africa. 

Super foods are all the rage, and argan oil has not escaped the trend. It reportedly has numerous health benefits and as such, has a name (and price) to match them. Argan oil is also a popular success story for many NGOs and international development charities in Morocco.

Argan trees are picky. According to Orwa's (et al, 2009) "Agroforestree database", the argan tree very well adapted to Morocco's climate, soils and ecology. To that extent, other regions of the world (Israel and Mexico) have only had some success with growing argan trees.

This mini series focuses on to what extent a particular crop is 'water-suitable'. The argan tree does not get more suitable in climatically dry regions with limited groundwater (Morocco). Argan trees do poorly in waterlogged soils (Orwa et al., 2009). Their deep roots help bind soils, promote infiltration, and provide it with access to deeper water reserves, reducing competition and making great trees to be intercrop with. Finally, they have seen success in halting the occurrence of desertification of the Sahara Desert across Southern Morocco (Orwa et al., 2009).

However, the water-suitability benefits are not the only advantages to argan. Argan, as previously mentioned, has been a success story across a number of NGOs (Lybbert et al., 2010). Argan can be sold for almost $400 per litre, so presumably has a large impact on rural poverty alleviation. However argan oil sales have been relatively insignificant in increasing household budgets, and have only some financial benefit on rural households (le Polain de Waroux & Lambin, 2013). For those who previously would heard goats, more vigilant households have begun preventing herders from using their trees for goats to graze upon, due to the value of the fruit (Lybbert et al., 2010). This has not only impacted herders, but also affected tree health, as goats were non-exploitative grazers. Furthermore, few households have invested back into local argan forests, further impacting the future sustainability of argan forests. 

It's like an adventure park for goats! (Source)

The future pressures are also rather significant. The argan tree is a highly tolerant species, which adapts well with little water in a harsh environment. As consumer demand and climate variability increases in the future, so will human and climatic pressures. Zunzunegui (et al., 2010) argues a combination of both pressures will have the largest impact on production. A sustainable  approach is therefore needed to reduce human pressures and mitigate against lower yields in the future. Although Zunzunegui's research was limited, the research warrants caution over exploitation.

Argan trees are perfect cash crops for Moroccans. They are endemic species, highly tolerant of the harsh environment, and highly water-suitable for the region. Future climatic impacts may alter the opinion of NGOs as fruit yields decrease and sustainable yields should be. For the short term, they give a rare and hopeful opportunity to alleviate poverty and improve the finances of those in rural Morocco.

Don't blame the tools #3: Money grows on trees!

This mini-series in my blog is dedicated to looking at how the use of 'water-efficient' and 'water-suitable' or 'regionally-appropriate' crops used can increase food security across Africa. 

Cash crops are popular for farmers, as they can provide a good source of income which allows farmers to purchase other produce and commodities. However, cash crops are widely agreed to be controversial, as they decrease food security and increase dependency on international markets (Maxwell and Fernando, 1989). The wider environmental and economic impacts of moving away from sustenance farming to 'cash crop' farming should not be ignored, especially when looking at the appropriateness of crops across Africa.

Cash crops or sustenance farming? (Source)

Maxwell and Fernando's (1989) review of the literature and existing research at the time is a good stepping stone for understanding the impacts of cash crops. Ultimately, the data on production volume was limited at the time, but amongst a number of other conclusions, there were a significant proportion of lower income countries whereby a good proportion (10%) of their GDP relied on the export of cash crops. Further to the increase in GDP, there are short-term advantages of cash crop-export. These include household stability and national investment, however longer term issues are frequently highlighted through an increased dependency on a single commodity, decreasing competitive advantages, especially against manufactured goods compared to primary produce (grains, etc.) and increasing vulnerability to volatility in the market. In these instances, "high production and consumption linkages" crops are required, especially if they are used in secondary industries. 

The economic advantages are clear. Cash crops are important and promising to poorer households who can see these crops as a means to generate extra income, and potentially generate extra employment. Policies can be included to guide households (Von Braun and Kennedy (1986)), but ultimately food security was found to not be negatively impacted, and instead increased production and availability of food security on household and national levels. However, what is not discussed is whether the increase in food security is stable over time (i.e. not varied throughout the year due seasonal sales of crops) and the quality of the food security. This extends to employment, as although employment is increased, the temporal and spatial distribution of the increase, as well as the remuneration received is limited in research.

There is a strong case for small-scale cash crop farming, which is economically and socially important in providing empowerment of rural farmers and women, as well as aiding countries on a national level. There is need for a middle ground policy which drives sustainability in food production and limit dependence on mono-crops. Von Braun and Kennedy (1986) advocate this view and have provided detailed national level requirements to ensure resource balance, effectiveness of cash crops, and efficient growth while protecting the environment and wider society. Finally the suitability of cash crops to a particular region should detailed. Limited data exists on the water requirements, let alone the environmental impacts and suitability.

I hope to provide a greater understanding of cash crops, their water requirements, and impact upon food security during the next few blogs.

Don't blame the tools #2: Coming out of the Maize

This mini-series in my blog is dedicated to looking at how the use of 'water-efficient' and 'water-suitable' or 'regionally-appropriate' crops used can increase food security across Africa. 

For those who do not have the means to irrigate crops, rainfall is the primary means of getting water to crops. Uneven distribution of rainfall exposes crops to a range of rainfall variability, which potentially affects crop yields. Mitigation against variability and reduced rainfall periods are limited, and tend to be dependent on soil water capacity, crop water demand, crop water uptake and freshwater/ groundwater availability (Barron, et al. 2003). 

Across much of Sub-Saharan Africa, the crops in question tend to be Maize (figure 1). Maize is a widely popular staple crop across Africa and globally relied upon, due to its climate, soil and salinity versatility. Furthermore, Maize is a great crop for semi-arid parts of the world as it can withstand reduced water supply for 15 days before having a significant impact upon overall yields (Barron, et al. 2003).

Figure 1: dominant grain production across Africa
(adapted from Yam-Bar, 2013)

Therefore it is generally agreed that the use of Maize is appropriate across Africa, due to its water efficiency and high yield (Barron, et al. 2003; FAO, 2015). 

This would normally be the end point of this blog series, as a range of sources indicate that Maize is a highly appropriate crop for the region give its low water consumption and high tolerance of almost all factors. As Maize is a wide spread and heavily relied upon crop across Sub-Saharan Africa, it is a very researched crop and the future success of Maize in light of climate change has been examined. 

A team from Princeton University studied rainfall and evaporation trends from 1979-2010 to understand how changes would impact Maize yields. They found increases in water availability during the Maize growing season, with some regional variability (Figure 2 (Blue is an increase in water availability over time, red is a decrease)). The research accounts for 34% of all Maize across Africa, and provides a means to examine where water stress might occur and mitigation strategies are required. 

Figure 2: Water availability during Maize growing season
 (Estes et al., 2014) 

Work has gone into solving or mitigating against the issues of water availability in East Africa through development of water-efficient crops. WEMA is a public-private partnership who's goal is to develop and distribute water efficient and insect resistant Maize to stabilise yields and improve food security (WEMA, 2012). Although ethical and environmental issues are prevalent in selective breeding of crops, it insures future availability and sustainability of Maize and food security in the face of climate change.

Maize is not just an important staple crop. In South Africa, the price of Maize has significant influence over civil unrest whereby increases in global and national prices of Maize has triggered labour and xenophobic riots and violence (Yam-Bar et al., 2013). Although Yam-Bar (et al., 2013) comprehensively explores the relationship between civil-unrest and food prices, prices of food tend not to be the initial trigger factor in civil unrest (Deininger, 2003).

The importance of Maize in Africa must not be ignored. It is widespread, adaptable, and an important socio-economic pillar in various cultures and regions across the continent. However, future reductions in water availability in East Africa and continent-wide population could impact food security if mitigation strategies are not implemented.

Don't blame the tools #1: Millet

This mini-series in my blog is dedicated to looking at how the use of 'water-efficient' and 'water-suitable' or 'regionally-appropriate' crops used can increase food security across Africa. 

To meet world demand for food production in the future, changes have to be made with regards to how we look at agriculture. There is a large demand to increase efficiency of yields without increasing land consumption. However, land and water availability are constrained, and not always available in the quantities required to increase efficiency. Therefore, if you cannot change the inputs of the agriculture, you might consider the most efficient or practical crops to grow.

The next few blogs will be dedicated to looking at how food security can be increased across Africa (and the world) through what crops and farming practices we choose to use and the differences which need to be fully understood and quantified.

Millet, a highly productive cereal crop,
grows well in semi-arid regions (Source)

Millet is a cereal crop found across much of the semi-arid regions of Africa, and predominately found in the Sahel region of Africa (Debenport et al., 2015). The Sahel is 3 million km2 region of desert (Sahara) and wooded savannah (Sudan). Rainfall on average is between 200-600mm ±15-30% per annum (FAO, 2011).The crop has been widely studied, with special focus on its productivity in the Sahel. Millet tends to be grown in sandy soils and intercropped with other crops (FAO, 2011). The FAO (2011) report found that for every mm of water per hectare used on millet, there is a yield of 3kg.

The FAO's (2011) report also provides suggestions for improvement of yields in this region. Due to the low water requirements of millet, it is a suitable plant for the region. Some of the improvements include intercropping with other crops. Debenport (et al., 2015) explains that intercropping millet with other crops significantly increases crop yield. Soegaard and Boegh (1995) echo this improvement, suggesting that most millet production across Africa is low efficiency, due to low crop density allowing for high evapotranspiration and water loss from soils - intercropping increases crop density. However the FAO (2011) do suggest other crops, such as sorghum, would be more suited to the region, as they have a higher biomass productivity rate compared to water consumption.

Changing crops from millet to sorghum, therefore, would increase food production and security without the need for increased water supplies. However, when considering suggestions such as these, you need to look at the socio-cultural implications of changing crops: is there availability of seed, skills to plant, farm and harvest, and knowledge of how to cook new crops?

Virtual Water: a virtual solution?

The concept of "virtual water" has been widely discussed as a solution to water-stressed states with low hydro-political security, such as the Middle East and Africa. The term was suggested initially by Allen (2001), and describes trading of the water footprint contained within commodities from water-rich to water-scarce countries. Virtual water, although heavily reliant on a country's potential to purchase and import goods from water-rich countries, has the capacity to provide states with goods they would otherwise not be able to produce with the water available to them.

Previously I discussed Africa's "underground oceans", explaining that low yielding aquifers have the potential to supply water to a large proportion of the continent's population and agriculture. However, some of this groundwater is inaccessible without large drilling tools (Bonsor and MacDonald, 2011).

Figure 1: Depth to groundwater in meters below ground level.
Greatest depths found in N. , E. and Central S. Africa
(Bonsor and MacDonald, 2011)

Both North, East and Central Southern Africa have the deepest aquifers (Bonsor and MacDonald, 2011) and hence could benefit most from virtual water trade. Earle and Turton (2003:183-200) found that although the countries of the Southern African Development Community (SADC) have good access to water, there is large spatial and temporal variation across the region, and water stress is expected to rise with climate change. Earle and Turton (2003) find that although virtual water trade is low, investing and trading in grain production from economically-poor but water-rich states, to economically-wealthy but water-stressed states is a more sustainable means of supporting growing populations and alleviating poverty. The trade of water through crops mitigates the need to build large, transnational water-sharing infrastructure projects, which could be costly. Similar findings are discussed by Konar and Caylor (2013) where countries with small dam storage tend to rely more on virtual water imported in commodities to mitigate against poor natural water stores and poor production yields.

Virtual water, although an interesting concept, cannot be relied upon by states. Free trade and lower import costs are required by poorer, water-scarce countries if virtual water is to be used as a water management strategy during times of drought, or by water-scarce countries. Furthermore, food security and economic productivity would be greatly harmed with greater reliance on virtual water, especially in poorer states where food prices are high and primary industries are a dominant source of income for locals and governments.

Africa requires agriculture; the search for a solution continues.

Africa's underground oceans

Oceans cover approximately 70% of the world, with 97% of world's water held in oceans. To put that into easier figures, there are 332,519,000 miles3 of water on earth, or 352,670,000,000,000,000,000 gallon-sized milk containers. Facts like these are easy to find (NOAA, 2015), but these figures hide the importance, necessity and access to water across the human-inhabited world, i.e. not the ocean. 

To get a better understanding of the volume of water on Earth, the images from Randall Munroe's online question blog give a good understanding of how much of Earth's land mass is covered by water.

Sea level decrease of 5km (Munroe, 2013)

Freshwater only accounts for 3% of all the water on Earth. The temporal and spatial distribution of freshwater however tends not to match the temporal and spatial distribution of human populations. Therefore, some regions of Earth are known to be water stressed, where the availability of water is not always where it is required.

Until recently, the total volume of Africa's groundwater supply was unknown.

Simplistic older hydrological models in Africa would identify one figure for infiltration and assume that covered the groundwater interaction (Kutzbach, 1980). Although this method is useful if looking at above-surface hydrology, there are sub-surface interactions that can further impact the hydrology of a basin further than being an 'output'.

MacDonald (et al., 2012) provides insight into the stored capacity of groundwater across Africa. The article estimates there to be 0.66 million km3 of freshwater capacity in Africa, with the greatest reserves in Northern Africa, and potential yields of certain regions. MacDonald (unclearly) claims that due to low transmissivity in Sub-Saharan Africa, the geology is limited for intensive irrigation. However, groundwater abstraction is still possible in Sub-Saharan Africa in areas of low water demand.

Groundwater storage with rechargein Africa
(water depth in mm) (MacDonald et al., 2012)

Although MacDonald's (et al., 2012) work is highly beneficial to international aid and development networks, there is a warning that it does not discuss. Groundwater can have a long recharge rate, especially with increasing population and more intensive abstraction. Hence, careful planning by researchers, governments and local communities should be undertaken in order to sustainably mine Africa's underground ocean.