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.