Having concluded in my previous post that improving water and land productivity in crop production is the most obvious method of increasing food security and decreasing poverty, the next two blogs will introduce the practice of irrigation as a method of improving agricultural efficiency and decreasing vulnerability, and discuss its potential in the sub-Saharan Africa context through the lens of rural small-holders. The term irrigation can be defined as ‘the artificial application of water to land for the purpose of agricultural production’ (Figure. 1) (Agriculture
Victoria 2018). With little capacity to increase the amount of cultivated land in sub-Saharan Africa, irrigation is commonly proposed as a mitigating factor to the vulnerabilities (i.e. food shortages) inherently linked to rain-fed agricultural production (Battisti & Naylor 2009).
It is clear a holistic approach is required if the widespread food security issues in sub-Saharan Africa are to be ameliorated, including more effective technologies, policy and institutions in the agricultural sector (Xie et al. 2018). With crop production being predominantly rainfed in sub-Saharan Africa, using technology to provision expanded irrigation is a promising option (i.e. through access to groundwater) to boost agricultural productivity, improve food security and lessen import dependency in the region (Xie et al. 2018). Irrigated agriculture is significantly more high-yielding than rainfed agriculture with roughly 40% of global food production contributed by the irrigated 20% of global cropland (FAO 2016), current estimates suggest irrigation has the potential to boost agricultural productivity by at least 50% in sub-Saharan Africa.
Increasing the proportion of arable land under irrigation, especially in areas with highly variable or low rainfall (i.e. Zimbabwe) has previously been adopted as a method of improving food security (Taylor 2004). However, these irrigation structures are not common (only 4% of cultivated land) and have hugely varied water sources both across sub-Saharan Africa and between different farm-types. More commercialised farms utilise groundwater or river dams and more traditional smallholder farms utilise adaptive techniques such as rain-water dams and flood-recession agriculture (to be covered in a subsequent blog). Current estimations suggest smaller-scale agriculture accounts for roughly half of all irrigation in sub-Saharan Africa, however this is likely to be under-estimation due to inaccurate satellite imagery at this scale (Villholth 2013).
Despite technological efficiency improvements irrigation still requires the exploitation of freshwater resources, meaning that if there is no freshwater resource in proximity to the land then irrigation is unlikely to be feasible. Another geographical aspect limiting the potential feasibility of groundwater irrigation is the high evapotransporative flux existing over significant parts of Eastern and Southern Africa. These climatic conditions demand up to twice as much water for irrigation as more temperate latitudes, meaning roughly 17500m3 is required per hectare (Xie et al. 2018). Significant knowledge gaps endure as to the particular role irrigation could have in the complicated sub-Saharan water-food nexus. The feasibility of costly and complex irrigation expansion is influenced by a multitude of factors, summarised as both biophysical and socio-economic in nature (Xie et al. 2018). The next blog will explore a form of irrigation applicable to the current sub-Saharan Africa context (groundwater irrigation) and assess its relative merits, drawbacks and geographical applicability.
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| Figure 1. A farmer in northern Ghana adjusting the irrigation pipe sprinklers (SciDevNet 2019). |
It is clear a holistic approach is required if the widespread food security issues in sub-Saharan Africa are to be ameliorated, including more effective technologies, policy and institutions in the agricultural sector (Xie et al. 2018). With crop production being predominantly rainfed in sub-Saharan Africa, using technology to provision expanded irrigation is a promising option (i.e. through access to groundwater) to boost agricultural productivity, improve food security and lessen import dependency in the region (Xie et al. 2018). Irrigated agriculture is significantly more high-yielding than rainfed agriculture with roughly 40% of global food production contributed by the irrigated 20% of global cropland (FAO 2016), current estimates suggest irrigation has the potential to boost agricultural productivity by at least 50% in sub-Saharan Africa.
Increasing the proportion of arable land under irrigation, especially in areas with highly variable or low rainfall (i.e. Zimbabwe) has previously been adopted as a method of improving food security (Taylor 2004). However, these irrigation structures are not common (only 4% of cultivated land) and have hugely varied water sources both across sub-Saharan Africa and between different farm-types. More commercialised farms utilise groundwater or river dams and more traditional smallholder farms utilise adaptive techniques such as rain-water dams and flood-recession agriculture (to be covered in a subsequent blog). Current estimations suggest smaller-scale agriculture accounts for roughly half of all irrigation in sub-Saharan Africa, however this is likely to be under-estimation due to inaccurate satellite imagery at this scale (Villholth 2013).
Despite technological efficiency improvements irrigation still requires the exploitation of freshwater resources, meaning that if there is no freshwater resource in proximity to the land then irrigation is unlikely to be feasible. Another geographical aspect limiting the potential feasibility of groundwater irrigation is the high evapotransporative flux existing over significant parts of Eastern and Southern Africa. These climatic conditions demand up to twice as much water for irrigation as more temperate latitudes, meaning roughly 17500m3 is required per hectare (Xie et al. 2018). Significant knowledge gaps endure as to the particular role irrigation could have in the complicated sub-Saharan water-food nexus. The feasibility of costly and complex irrigation expansion is influenced by a multitude of factors, summarised as both biophysical and socio-economic in nature (Xie et al. 2018). The next blog will explore a form of irrigation applicable to the current sub-Saharan Africa context (groundwater irrigation) and assess its relative merits, drawbacks and geographical applicability.
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