Elsevier

Agricultural Water Management

Volume 168, April 2016, Pages 125-135
Agricultural Water Management

Transitioning to groundwater irrigated intensified agriculture in Sub-Saharan Africa: An indicator based assessment

https://doi.org/10.1016/j.agwat.2016.01.016Get rights and content

Highlights

  • Provides a concept of transition to groundwater irrigated agriculture.

  • Develops a multi-dimensional transition index using principal component based methods.

  • Identifies four intermediary indices for assessment on the transition potential.

  • Assess ten case study countries on the basis of derived indicators.

  • Suggests strategies for groundwater development in Sub-Saharan Africa.

Abstract

Growing populations, changing market conditions, and the food security risks posed by rainfed cropping and climate change collectively indicate that Sub-Saharan African nations could benefit from transforming agricultural production to more intensive yet resilient and sustainable systems. Although highly underutilized, emerging evidence indicates that groundwater may be more widely available than previously thought, highlighting its potential role in facilitating such a transformation. Nevertheless, the possibility for such a transition is conditioned by number of complex factors. We therefore construct a transition index that integrates data considering groundwater and energy availability and cost, market access, infrastructural needs, farm conditions and natural resource stocks, labor availability, climate, population density, as well as economic and political framework variables, using a principal component analysis based methodology. Using the consequent multi-dimensional transition index and constituent intermediate indices, we provide an assessment of groundwater irrigation potential discussed in consideration of Burkina Faso, Ghana, Malawi, Ethiopia, Nigeria, Zambia, Namibia, Cameroon, and Zimbabwe. Our results, though preliminary, provide a methodology for conducting such an integrated assessment, while deriving a holistic set of policy options considering the transition towards appropriate use of groundwater for agricultural development.

Introduction

Sub-Saharan Africa's (SSA's) predominant agricultural systems are generally characterized by rainfed and extensive crop and pastoral systems, many of which experience yield gaps and are well below their productive potential (Tittonell and Giller, 2012). The extremely low use of fertilizer (1% share in world fertilizer market) and irrigation provision (3% of the cultivated area) of this region reflect these underlying characteristics and the subsistence nature of farming (FAO, 2008). It has been suggested that a transition to more intensive agricultural production systems designed with sustainability and resilience principles in mind could help to address the challenges of meeting the food security and livelihood demands of SSA's increasing populations (Hazell and Wood, 2008, IFPRI, 2012), while maintaining ecosystem services and protecting rangelands and forests from conversion to cropped agriculture (Fisher, 2010, Palm et al., 2010, Vanlauwe et al., 2014). Though there is a constellation of factors responsible for the current state of SSA's predominant agricultural systems, dependence on rainfed production is a major factor influencing farmers' high level of risk aversion that limits investments in more intensified farming systems (Haile, 2005, Rockström et al., 2010). It has been argued that the environmentally sound provision of irrigation could be a key factor enabling a transition from low to more sustainably intensified systems that could benefit smallholders (Burney and Naylor, 2012), while buffering against the anticipated negative repercussions of climate change (Lobell et al., 2008). Given recent studies showing that groundwater is more prevalent in SSA (MacDonald et al., 2012) than previously thought, the current study analyzes the factors that could enable or hinder the transition to groundwater based irrigated agriculture in a sub-set of SSA countries.

In countries where groundwater is physically available, the potential for economic gain (profit differential) that could be realized from the transition from predominantly rainfed production to irrigated agriculture, which we term it as transition pressure, could be a driving force in the intensification process (Amjath-Babu and Kaechele, 2015). It should be noted that numerous social, agronomic, economic and environmental factors must be aligned to encourage the transition process (Godfray and Garnett, 2014). The current work looks at the interactive nature of these determinants. The pressure to transition to more intensively irrigated production is currently low in SSA and one must consider the underlying institutional, economic, energetic, hydrogeologic, climatic, societal, and policy related causes that impede the transition to sustainable intensification. Such an understanding could reveal potential pathways and areas of investment to facilitate the sustainable use of groundwater for irrigation, which could have important ramifications for food security and income generation in many of the SSA countries studied.

Rapidly increasing populations, economic growth, and climate change make the transition from low productivity farming to a more intensive yet environmentally and socially sustainable agriculture an important task in the context of SSA. In SSA, population growth has outpaced the growth in food production (Johnson et al., 2003), with a number of countries becoming net food importers or food aid receivers. In 2008, Sub-Saharan African nations imported 21.9 million tons of grain equivalents while an additional 4.2 million tons were received as food aid (USDA, 2010). Another development that underscores the importance of such a transition is the recent escalation in food prices (Mitchell, 2008), which exposed the vulnerabilities of the current world food supply and pricing system, with special relevance to cereal crops and SSA. Nevertheless, avoiding a long term persistent food crisis is likely to be of greater concern than dealing with short term price escalations (Battisti and Naylor, 2009). In addition, provision of irrigation for smallholders can also be a key tool in poverty alleviation and meeting developmental goals (Burney and Naylor, 2012).

Barrios et al. (2008) showed that undesirable changes in precipitation and temperature from the 1960s onward can account for a major share of the production deficit in SSA (in comparison to other developing country regions). The sensitivity of farm income to precipitation is evident from a number of studies using Ricardian approaches. The elasticity of rainfall to farm income ranges from 2.5 in Ethiopia (Molua, 2009) to 3.18 in Kenya (Kabubo-Mariara and Karanja, 2007). It has also been reported that increased temperature scenarios projected for SSA can improve average farm income under irrigated conditions (the elasticity of temperatureto income being 0.5), while it can substantially harm rainfed farming (where the elasticity is −1.9) (Kurukulasuriya et al., 2006). Hence, in order to move African agriculture towards climate resilience, i.e. less sensitive to rainfall and temperature changes, while meeting the increasing demands of a growing population and economy, a transition to (supplementary or fully) irrigated cropping is likely to be essential. Unlike the previous green revolution that bypassed SSA, the sustainability of planned intensification efforts is an important consideration in the African context in which socially equitable and environmentally sound development is needed (Horlings and Marsden, 2011).

Induced innovation theory seeks to explain the transition from traditional agricultural systems that are heavily reliant on land expansion and labor inputs to maintain or increase production, to intensified farming systems. The theoretical premise is that population pressure and scarcity of land induce adoption of intensive farming practices which in turn encourage associated institutional change in an ultimately reflexive and mutually supportive cycle (Hayami and Ruttan, 1985). While we recognize that smallholders are as interested in risk reduction as they may be in profits (Tittonell and Giller, 2012), for the purposes of this study we assume that the profit differential between these systems that can be realized under local physical, economic, social and infrastructural conditions can adequately reflect the transition pressure that could induce the adoption of innovations in farming practices. The concept is presented in Fig. 1. As the focus of this paper is to analyze the potential of groundwater based irrigated intensified agriculture in Sub-Saharan Africa, we construct a preliminary index that could reflect such a transition. The domains considered for this index include groundwater, energy, markets, infrastructure, farm conditions, labor availability, climate, population and economic pressures, and political stability. The sub-indicators selected for the construction of the transition index are average depth to groundwater table and average yield of groundwater wells for the domain ‘groundwater’, rural electricity access and diesel price for the domain ‘energy’, average travel time required to reach a populated area with markets, and the farm gate price of representative marketed crop (maize predominantly) for the domain “market”. The average cost of drilling boreholes (per meter depth) and the percentage of paved roads were both used for the domain ‘infrastructure’, and average nutrient depletion rate for nitrogen, potassium, and phosphorus, and the value cost ratio of fertilizers, were used for the domain ‘farm conditions’. The percentage of land surface that contains 90% of the population was used as an index of population density in rural areas for the domain “labor availability’, while arable land per capita and GDP per capita were used for ‘population and economic pressure’. Mean precipitation represented the domain “climate” and fragility index for political framework conditions. The transition index was calculated for ten Sub-Saharan African countries, including Burkina Faso, Zimbabwe, Cameroon, Namibia, Zambia, Nigeria, Ethiopia, Malawi, Kenya and Ghana for which complete data were available.

Let us now present several points justifying the inclusion of these indicators in the transition index. Physical and economic access to groundwater are preconditions for groundwater based development and hence the depth to groundwater level, yield of wells, and cost of drilling and pumping are the defining variables in any assessment of groundwater’s agricultural potential. It is already well established that the excessive cost of well construction is identified as one of the major obstacles in groundwater development in Africa (Tuinhof et al., 2011). In addition, the availability and cost of energy sources, such as grid-based electricity and diesel fuel, partially determine whether the existing potential can be realized. In the absence of these sources, cost and availability of alternative sources of energy such as off-grid solar or wind sources may become relevant. Physical infrastructure like roads and market places can influence competitive price forming conditions, given the resulting space-time concentration of consignments of marketed surplus which leads to a decline in transaction costs (Von Oppen et al., 1997). This in turn increases the incentives to produce market oriented crops and increase their productivity, i.e. specialization and intensification effects. It should be noted that farm gate prices influence the level of inputs a farmer may choose to utilize, and increased output prices can obviously increase the transition pressure to intensive agriculture where farmers can access markets. The role of fertilizers and rainfall in determining agricultural output is exemplified by Malley et al. (2009), who showed that variation in output is predominantly (39% and 59% respectively) determined by these two factors.

The price and availability of fertilizer and mean precipitation are relevant to any effort to intensify irrigated agriculture in Sub-Saharan Africa. The availability of rainfall strongly characterizes irrigation demand; and along with soil and geological characteristics, it also strongly influences the rate of groundwater recharge. Nutrient mining and land degradation are also major factors that limit yields, and that influence food shortages, migration and conflicts in African nations (Henao and Baanante, 2006, Mutiro and Murwira, 2004). Restoring and maintaining soil fertility through the application of manures and fertilizers is a key factor in initiating the sustainable intensification process. Farmer participatory trials conducted in Zimbabwe indicated that combining smaller quantities (5–40 kg N/ha) with manure application (around 5 tons per hectare) can lead to sizable increases in marginal rates of return (up to 400% at 20 kg N with 5 tons of manure) (Mutiro and Murwira, 2004, Sterzel et al., 2014). In addition, already degraded lands may need a number of years of manure or organic matter application to regain a sufficient level of quality by which they may respond as desired to fertilizer inputs (Tittonell and Giller, 2012). In combination, these methods over time can assist in increasing fertilizer nitrogen use efficiency, an important parameter in cropping systems sustainability that has the additional benefit of lowering costs for farmers while improving yield (Krupnik et al., 2004). Other domains of interest include population and economic pressure. It should be noted that many of the countries in Sub-Saharan Africa cannot necessarily be considered as land abundant at their current level of land use intensity, and continued use of with extensive farming systems may not be feasible as populations and land pressures increase (Jayne et al., 2010).

Given the declining per capita land availability and increasing GDP of many Sub-Saharan African nations, one may expect that induced innovation could take root. In addition, the fragility of political systems can be a crucial aspect in determining farmers’ agricultural investment levels as less stable political environments may increase investment risk. Table 1 summarizes these constituent indices and mentions the data sources.

There is a dimension of risk in adoption of any intensification technology, including groundwater irrigation. Resource-poor farmers are generally risk averse in making investments with scarce capital and hence efforts to intensify farming have to take this factor into account. The transition index reflects the business (input and output prices, transport), agricultural (climate, labor availability), natural resource (groundwater depth, yield, soil fertility), infrastructure (paved roads, drilling machines) and political (conflict or political fragility) conditions in our study countries, and indirectly the risks associated with intensification. Additional aspects such as social risks (diseases, ceremony costs) and some business risks (post-harvest losses) are not covered by the index, for which data are sparsely available.

Major variables missing in the index are availability and cost of capital, as well as the presence and form of land tenure systems. Though the lending rate for prime customers in these countries is available, agricultural borrowers cannot be considered as prime borrowers. One has to consider also the fact that the formal agricultural credit market is rudimentary under African conditions. One major reason can be poorly-functioning land markets and inability to use land as collateral in banks. Communal ownership of land may also preclude external parties from owning land (Phillip et al., 2009). Nevertheless, as Fenske (2011) noted, the conversion to private property rights by registering pieces of land by individual names may not necessairly solve the issue, as neighbors may not buy the foreclosed land of an individual in a community. Hence one has to look at innovative financing mechanisms (public or private) to increase access to credit for rural farmers in SSA. However, there is more agreement on the fact that traditional land rights offer adequate tenure security for increasing input use such as fertilizer or water (Brasselle et al., 2002 and Fenske, 2011). Nevertheless, the lack of information on this issue meant that we were unable to include these considerations in the index formulation.

Section snippets

Database and methodology

The concept of transition and influencing factors described in the previous section serve as the basis to select data to indicate important underlying processes. All data are provided by existing databases capturing transition processes at national resolution. The data for the groundwater sub-indicators were extracted by taking the mean value of depth and yield data reported by MacDonald et al. (2012). Data for the energy domain (diesel prices at Pump) comes from the World bank database (//data.worldbank.org

Results and discussion

Principal component analysis revealed four components which are translated to four intermediary indices (Mjk) that are appropriately named (considering the constituent indicators) as, framework conditions, policy instruments, farm conditions, as well as, market and farm constraints, (Table 3). The four intermediate indices are later summed to create the transition index (Tj). Framework conditions represent groundwater access, population, GDP per capita, rainfall and political stability. These

Recommendations on transition possibilities

Groundwater appears to be more widely available as a resource in SSA than commonly thought, though its potential for sustainable use to intensify agriculture is considerably different among countries, due to a number of reasons that are discussed in detail for each country covered in this study. The development of groundwater resources could be quite important in SSA given population pressures, economic growth, climate change and poverty alleviation challenges. It is already known that when

Limitations of the study

The quality of data used in some sub-indices in this study may not be as high quality as other indices, a situation that limited our work but nonetheless indicates the quality of data typically available in SSA. Some data points were time inconsistent, though we are not expecting rapid changes in these indicators. Another area that is relevant to the domain of labor is HIV/AIDS prevalence in particular parts of SSA that is reported to affect labor availability, although we were not able to

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