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. 

What do mobile phones have to do with irrigation?

One obstacle that prevents farmers from implementing irrigation schemes in the most efficient way on their farm is their lack of knowledge. Training every farmer on how best to manage water seems unrealistic due to the costs and time required. However, I came across an article that talks about making use of what most African farmers already have (mobile phones) and using texting as a means of communicating valuable information. The article talks about a pilot project, which was carried out in Egypt, Sudan and Ethiopia, where information and weather advice was provided to small-scale farmers over SMS.  

Farmers using phones on a farm in Uganda (Source)

The whole trial was generally positive, and it sounds like this could be a method that may well be used in the future to help farmers with the management of irrigation. I did some further research on this and came across this paper, written by A. Singels and M.T. Smith describing a pilot SMS model, like the one in the article, being used as a trial in South Africa.  Unlike my previous posts, this post will look at the situation of farms post-irrigation.  The paper states that the irrigation techniques used in South African sugar cane farms have not been so positive due to over-irrigation, and that irrigation schemes have had very low water efficiencies and reduced profitabilities. This is due to:

·      The difficulties in using technology and applying information gathered using technology in practice on the farm.

·      Farmers having the perception that accurate irrigation scheduling has little benefit to crop yield, especially small-scale farmers who do not have access to monitoring equipment or the internet to help them schedule their irrigation.

So although irrigation has been implemented in this instance, it is not being used in the best way. There needs to be a means of allowing farmers to access and understand crop growth models and weather predictions so that they can use their irrigation instruments in the most optimal way.

Irrigation can be scheduled to meet certain targets, such as to maximise profits or to maximise water use efficiency and minimise water wastage. Models have been developed to calculate irrigation schedules, which provide watering dates and subsequent watering quantities to meet these targets, but farmers have often found these models too complex and difficult to understand. So models need to be simplified with straightforward advice so that farmers can receive user specific guidance that can be applied easily. The paper describes a centralised irrigation model (My Canesim as shown in Figure 1) that provides real time advice, such as the advice shown in Table 1. The system was evaluated using the following criteria:

·      A comparison of the long-term performance of the irrigation advice given by the system to current irrigation practices.

·      The implementation of the system on several fields, with a focus on crop growth, water use and farmer acceptance.

Figure 1: My Canesim network

Table 1: The five different options of irrigation advice 

The paper found that measurements taken by farmers on rainfall and irrigation were generally unreliable. Some farmers also initially ignored advice from the SMS systems and needed reassurance that the advice would be beneficial, as some of the advice was quite contradictory to their usual practices. 

The paper states that the pilot project did improve yields and provide helpful advice, but farmers would need regular communication to convince them to take on board the advice. This is understandable, as farmers may find it hard to suddenly trust an external source of information that is being generated by a person who has not even seen their farm. However, I believe this has the potential to be a good method that can be implemented quite easily, given that many farmers nowadays have mobile phones. This is not to say I do not have any concerns with the model.

Here are some problems I thought of when reading about this type of SMS-based communication system for irrigation:

1)   Costs to run the system- there would need to be data analysers, crop experts and hardware and software engineers to ensure that the whole system runs smoothly. There is no mention of farmers paying to use this system, however, I imagine a lot of funding would be needed from governments or NGOs if this system were to be used on a large-scale.

2)   Accountability – advice may be inaccurate in some cases and there is a risk of farmers suffering devastating losses if the advice is misinterpreted or unreliable. Who is to blame in this case?

Despite the potential problems, an SMS-based model could be a step forward in making the most of irrigation schemes. Not only would it help farmers increase their crop yields, but also ensure that water is being used in the best possible way with as little wastage as possible, which is really important in areas that are water scarce or have little access to water.

Sub-Saharan Africa’s small-scale farming future

My two previous blog posts talk about the potential for small-scale irrigation to increase yields, benefit farmers, and consequently improve social and economic development. But I wanted to take a step back and look at smallholder farming practices in general in Sub-Saharan Africa, regardless of irrigation. The future of small-scale farming is worth looking at, as there would be no point in developing small-scale irrigation technologies and encouraging the implementation of them if smallholder farming does not have a secure place in the Africa’s farming future.

It is also important to consider the challenges of smallholder farming, and whether the benefits of small-scale irrigation make smallholder farming worthwhile despite the challenges. I have decided to look at an article written by T.S.  Jayne, David Mather, and Elliot Mghenyi, titled ‘Principle Challenges Confronting Smallholder Agriculture in Sub-Saharan Africa’, and I will focus on the issues that may hinder the implementation of small-scale irrigation technologies.

The aim of the study was to highlight the growing challenges of smallholder agriculture in Sub-Saharan Africa and to review the policy and public investment options to address these issues, which the researchers believe to be key influences impacting smallholder farming in Sub-Saharan Africa. Using survey data from Kenya, Malawi, Mozambique, Ethiopia, and Zambia, Jayne et al. identify empirical similarities in terms of problems. The five countries that were studied were chosen according to the availability of data sets, with the majority of data being collected by national statistical services. Although this was probably the most feasible method of finding and collecting the appropriate data, national statistical services can vary between each country, and the reliability of the surveys conducted can be debatable. Some surveys were devised by ministries and government bodies, such as in the Mozambique, whilst the surveys carried out in Kenya were created entirely by universities. It is important to be wary of who created and published the survey data, as government-published statistics could potentially be biased in order to create a more positive representation of the actual reality. Nonetheless, there is a thorough description of each type of survey used in each country and how the samples were selected.

The paper describes how there has been a steady decline in land-to-person ratios, meaning that the area of arable land that each person controls is getting smaller and smaller. For example, more than 25% of the small-scale farms that were surveyed were controlling less than 0.11 ha of farmland per capita, meaning they are getting close to landlessness. Farmers tend to settle where there are advantageous agro-ecological conditions and where there is easy access to markets, resulting in highly dense farming settlements with competition for resources. There remains lots of free land in rural areas, but the undesirable remote locations mean that no one wants to move there.

The farms were also ranked by per capita land size and divided into four equal quartiles to reveal some surprising results – for example, a doubling of income from crops in households that were in the bottom quartile (such as by switching to new technology or increasing inputs such as fertilisers) would have a minimal impact on their absolute level of income. This is a point worth elaborating on – if per capita farm areas are getting smaller and smaller, are implementing irrigation schemes really going to be cost effective? It may be cost-effective for the government to invest in an improved water source such as a water tap or well if there are many farmers concentrated nearby.  But for the farmers operating on the smallest scales, irrigation may not be an affordable option. Furthermore, if farmers are operating so close together, then using small-scale irrigation schemes like motor pumps would not be so effective as water collection waiting times would increase, and supplies may be used unsustainably. This is a catch 22 as many governments in Sub-Saharan Africa do not have the money to develop water sources in rural areas where population densities are low, however, rural water investment is probably needed the most so that farmers can disperse, have more land, and become more productive. The paper states that government spending in Africa has not tended to support the most rural farmers, which has been one of the reasons that Africa’s crop productivity has remained stagnant since 1961 whilst there have been improvements in productivity in the rest of the world. The paper concludes that most small farms in Africa are becoming more impractical and are becoming ‘increasingly unviable as sustainable economic and social units’ (Jayne et al.: 1394). The paper does not only give land distribution as the only reason for this, it also talks about crop market performance, crop prices, barriers to non-farm employment and the HIV/AIDS epidemic.  The paper suggests that the barriers that prevent the implementation of ‘productivity-enhancing inputs’ need to be removed by changing policies, increasing public spending on agriculture, and putting more research into the agricultural sciences of small farms rather than large-scale farming.

In my opinion, the paper was quite unoptimistic about the future of small-scale farming. Although the purpose of the paper was to examine the challenges of smallholder agriculture, I thought it was quite narrow-minded in the way it implied that the only influential actor that could address these challenges was the government and large international organisations such as the World Bank. It had limited scope on bottom-up approaches and ignored a crucial actor in development, which are non-governmental organisations (NGOs). NGOs have had a big role to play in all sectors of Africa’s development, and I believe that they have potential to influence the future of smallholder agriculture by investing in new technologies and training farmers.  One example of an NGO helping small-scale farmers in East Africa is ‘Farm Africa’.

A screenshot of the NGO Farm Africa’s webpage.

The NGO has carried out many projects that have empowered small-scale farmers. For example, Farm Africa have trained farmers in Ethiopia to use ‘climate-smart’ farming methods including irrigation. This could be an alternative to the dominant top-down approaches that were discussed in the paper.