The effect of salinization on food
security in Senegal
A case study on rice production
Suzanne Holleman
- 10171037 - Biology
Sofia van Holsteijn
- 10745572
- Political sciences
Emy Latul
- 10726306 - Biology
Cynthia van Leeuwen - 10767924 - Earth sciences
University of Amsterdam
Future Planet Studies
Interdisciplinary project
June 2, 2017
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Abstract
Senegal is one of the most underdeveloped countries in the world in which food insecurity is a pressing problem, despite it being democratic and stable. The Senegalese government set a goal to be self-sufficient in rice production by 2017, however this goal was not met. This can be partly contributed to rising salinity in agricultural soil in Senegal. Increasing salinization caused by factors like climate change, desertification and poor irrigation thus adversely influence the food security in Senegal. In this interdisciplinary research, the causes and impact of salinization on food security in Senegal is described to better understand this problem. The Driver-Pressure-State-Impact Response (DPSIR) model is used to analyse the effects of soil salinization in Senegal on its food security, focusing specifically on rice production. With this framework, a structured analysis is provided for the Senegalese government which can be used to improve their plan in being self-sufficient in rice production.
3 Table of contents 1. Introduction ... 4 2. Theoretical framework ... 6 2.1 Food Security ... 6 2.2 Entitlement Approach... 6
2.3 World System Theory ... 6
3. Methodology ... 8
4. Results ... 10
4.1 Drivers ... 10
4.1.1 Population growth & urbanization ... 10
4.1.2 Lack of knowledge ... 11
4.1.3 Rice preference ... 11
4.2 Pressures ... 11
4.2.1. Climate change: weather extremes and droughts ... 11
4.2.2. Irrigation schemes ... 12
4.2.3 Construction hydropower dams ... 12
4.3 State ... 12
4.3.1 Soil quality: salinization ... 13
4.3.2 Plants and agriculture... 13
4.3.3 Microbe-plant interaction ... 13
4.4 Impact ... 14
4.4.1 Food security: dependency on rice import ... 14
4.5 Response ... 15
4.5.1 Resistant rice cultivars ... 15
4.5.2 Growth-promoting rhizobacteria (PGPR) phytoremediation ... 16
4.5.3 Sustainable agriculture ... 16
4.5.4 Improvement irrigation schemes ... 17
4.5.5 Education on irrigation ... 17
5. Discussion ... 18
6. Conclusion ... 18
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1. Introduction
Senegal, a country located in the tropical, semi-arid climate of the Sahel region, has a total of 14.3 million inhabitants (CIA, 2016). For many of these inhabitants food security is still a big problem, even though Senegal is a democratic and stable country (The World Bank, 2016). The country is facing seasonal flooding of lowlands and periodic droughts, making agriculture difficult to practice. An important part of food security is the state of agriculture. With soil salinization as a threat to the quality of agriculture, it is necessary to analyse the causal links underlying this problem. Rice production has an important share in the economy of the country, with 906.000 tons being produced in 2015 (FAO, 2015).
The production of rice has increased over the past years due to the implementation of the Accelerated Program for Agriculture in Senegal (PRACAS) by the Senegalese government. Senegal had a total rice production of 469.469 tonnes in the period 2012/2013, which increased to 908.348 tonnes in 2015/2016, as shown in figure 1 (Ministère de l’agriculture et de l’equipement rural, 2013; 2016).
The aim of this program is to invest in irrigation schemes to increase the total rice production (Manikowski & Strappasson, 2016). By doing so PRACAS aimed to make Senegal self-sufficient regarding its rice production in 2017 (USDA Foreign Agricultural Service, 2015). However, figure 2 shows that in 2015 not a lot of progress has been made. The self-sufficiency level was only 25%, with still 75% of rice being imported.
Several factors may have caused the PRACAS plan to fail. For instance, salinization of the soil is reducing potential rice yields. Salinization has different climatic drivers, such as weather extremes and climate change. In the period 2014 to 2015, raining conditions were irregular at the begin of the season, delaying planting of rice. However, at the end of the growing season, extreme precipitation events occurred, damaging the crop (USDA Foreign Agricultural Service, 2015). Furthermore, the Intergovernmental Panel on Climate Change (2012) states
Figure 1 Rice production Senegal period 2012/2013 and 2015/2016 (Authors, 2017. Data used retrieved from Ministere de l’agriculture et de l'équipement rural, 2013; 2016)
Figure 2 Rice production, import and self-sufficiency levels. Retrieved from the International Rice Research Institute (2015).
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that West-Africa will experience more severe droughts in the near future. Climate change and climate extremes are likely to play a large role in the Senegalese rice production, as desertification and salinization are decreasing soil quality (Coumou & Rahmstorf, 2012). Next to climate factors, man has also contributed to decreased soil quality by salinization. During the 1980s two dams were built along the Senegal River Valley and estuary with the aim of hydro-power production and having a regular water supply for the irrigation of crops (Dumas, Mietton, Hamerlynck et al., 2010). However, next to decreased sedimentation of river material, salinization of the soil occurred as the salt water table intruded in the river delta. Consequently, the saline water moved upriver via the undercurrent of the Senegal River and the groundwater itself (Dumas et al., 2010). Furthermore, with often a lack of drainage applied to irrigated rice fields, salinization of the soil increases, reduces agricultural productivity by dehydration of plants (Ceuppens & Wopereis, 1999).
When looking at environmental problems, regarding salinization, it becomes clear why the aims of the PRACAS were not reached. The proposed plan is ambitious and mainly focussed on the economic goods needed to set up irrigated land, instead of on the environmental pressures that prevent the plan from succeeding. The USDA Foreign Agricultural service (2015) found that actions taken to reach the goal are mainly investing in (inefficient) rain fed rice production and irrigation systems. However, not much focus is put on the development of drainage systems or becoming more resilient to changing weather conditions.
To improve PRACAS to make Senegal self-sufficient, a DPSIR-framework is constructed to give an interdisciplinary view on the effects of salinization on rice production and ultimately food security in Senegal. This DPSIR-model also suggests mitigation options for affected areas. A theoretical framework is provided including theories that discuss aspects of the complex problem. From this framework the following research problem has been sketched. As said before, salinization of the soil in Senegal is a complex problem, as it has multiple drivers lying at its foundation (e.g. poor agricultural conduct, climate change, two dams in the Senegal river basin). This negatively influences agriculture in Senegal, thus affecting Senegal’s food security.
An interdisciplinary approach is required, as mitigation options are provided by different (sub)disciplines. To construct an interdisciplinary DPSIR framework and to improve the PRACAS plan, the following main question is stated: How does salinization influence the rice production, and thus the food security in
Senegal? In order to answer the main question the following sub-questions are answered: (i) What causes the
salinization of the soil in Senegal? (ii) How does salinization affect the rice production in Senegal? (iii) What can be done to improve rice production and thus food security in Senegal?
Based on the constructed DPSIR-model, mitigation are proposed. These measures could improve rice production and food security, as well as the overall ecological state threatened by salinization, as these factors are closely interlinked. Food security in Senegal will be analysed with Amartya Sen’s entitlement theory on famine (1981) and the World System Theory (Wallerstein, 1974) to analyse how the agricultural dependence of Senegal on the global rice market effects the local market and the food security.
With this interdisciplinary DPSIR-model an attempt is made to give a complete overview of the problem to provide mitigation and adaptation possibilities, as well as policy recommendations to meet the goal PRACAS has set. The following mitigation options are provided by different (sub)disciplines: soil quality improvement and irrigation scheme management (earth sciences), GMO usage (molecular biology) and sustainable farming and phytoremediation (ecology). Understanding the underlying theories behind these mitigation options is of great importance, requiring the disciplines earth sciences and biology. In order to achieve a fruitful application of these mitigation possibilities, sufficient knowledge is required of politics in Senegal, making the discipline political science necessary. With salinization as a threat in other food insecure countries as well, the findings and proposed recommendations for Senegal might be received as an example and could be implemented in other countries facing the same difficulties.
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2. Theoretical framework
2.1 Food Security
The idea of food security can be traced back to the 1948 United Nations Declaration of Human Rights, which included the “right to food” as a part of human rights. The term “food security” itself was not articulated until 1974 and did not dominate official discourse until the mid-1980s (Jarosz, 2011).The widely cited definition of food security according to the Food and Agriculture Organization of the United Nations is “Food security exists when all people, at all times, have physical, social and economic access to sufficient, safe and nutritious food which meets their dietary needs and food preferences for an active and healthy life.” (FAO, 2015). This view distinguishes between four pillars of food security. If all are fulfilled simultaneously then food security is achieved.
These pillars can be used to distinguish between certain types of cause for food insecurity, since the different dimensions have different indicators (FAO, 2016; Shaw, 2007). These pillars are:
1. Availability: there is a physical reliable and consistent source of quality food. 2. Access: people have sufficient resources to produce and/or purchase food.
3. Stability: people’s ability to access and utilize food that remains stable and sustained over time. 4. Utilization: people have the knowledge and basic sanitary conditions to choose, prepare, and distribute food in a way that results in good nutrition (Otero, Pechlaner & Gürcan, 2013). 2.2 Entitlement Approach
For decades the ideas of Thomas Malthus dominated the discussion on food security and famines. Malthus argued that food insecurity was caused by a lack of food supply because the food supply is limited while the growth of population creates a greater demand (Kurniawan, 2015). Sen’s new idea of the entitlement approach took over the popularity of the Malthusian approach.
Amartya Sen’s entitlement approach theory on food security explains food security as more dependent on access than on availability. He argues that food insecurity is not about the food supply failure. This approach shifts the focus of theorizing famines from the supply approach (Malthusian tradition) to the ability of people to access food (Devereaux & Berge, 2000). It relates to relative scarcity of food instead of the use of absolute scarcity of food as Malthus had used. With relative scarcity food is available for everyone, however not everyone is able to get it. There is more of a distribution problem than an absolute shortage of food (Scoones, Smalley, Hall & Tsikata, 2014). Malthus claimed that there was an absolute shortage of food in the world, however Amartya Sen claims there is a relative scarcity problem which stems from a distribution problem; how people access their food. This makes food security more of a socio-political problem than a food production problem.
According to Sen’s entitlement approach access to food depends upon the entitlements that people possess. There are two kinds of entitlements a person can have; endowments, which refer to the control of assets and resources such as labour power, and entitlements, which refer to ““the set of alternative commodity bundles that a person can command in a society using the totality of right and opportunities that he or she faces” (Sen, 1984 as cited in Devereux & Berge, 2000). People face famine if they experience entitlement failure, even though the food supply can still be available, if their set of entitlements does not provide them with adequate food (Kurniawan, 2015). Their set of entitlements can consist of several kinds of legal entitlements for acquiring food: growing it (‘production-based entitlement’), buying it (‘trade-based entitlement’), working for it (‘own labour-based entitlement’) and being given it (‘transfer- or inheritance- entitlement’) (Devereaux & Berge, 2000).
2.3 World System Theory
The World System Theory is a Marxist theory that explains international relations, mainly trade and development. It provides a theoretical structure whereby the global scope, historical perspective and the international economy are combined (Roberts & Grimes, 2002). The theory is mostly attributed to Immanuel Wallerstein: the world economy according to him consists of three zones where countries or regions may be located in: the core, the semi-periphery and the periphery.
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The three levels are located in an exploitative relationship with each other, wherein the wealth is drained from the periphery to the core, whereby the periphery experiences trade deterioration (Hobden & Jones, 2014). Inequality thus correlates with the structure of the world economy (Hobden & Jones, 2014).
As globalization and transnational governance has increased for the last decades, and institutions such as the World Bank and IMF were established, the relevance of the World System Theory in this form has declined. States are more interrelated and interdependent on each other, and with the rise of international institutions and intensive international trade the clear-cut division between the core, semi periphery and periphery is declining. However, it is argued that institutions such as the World Bank and IMF belong to the core of the world economy and is in an skewed power balance with states and institutions in the periphery (Roberts & Grimes, 2002). WST can be applied to the Washington Consensus which arose in the 1990s, whereby the World Bank and IMF would only give loans to developing countries if they implemented policy reform packages, which were good for global trade liberation but not necessarily good for the country's’ economy (Han, Lim & Byun, 2009). Countries and organizations of the core still use rules and restrictions as conditions for loans or financial aid (Han, Lim & Byun, 2009). Therefore countries and organizations that exist in the core of the world economy still are in a skewed power relationship with countries that are in the periphery of the world economy. The structure of the World System Theory remains the same with the development of globalization and establishment of international institutions, as these institutions can also be placed in the structure.
2.4 Theory of natural selection
Different rice species are grown over the world under a variety of environmental conditions. Traits that are favourable in one specific habitat might be neutral or even negative under different conditions. Individuals with favourable traits are more successful in surviving and reproducing (Freeman & Herron, 2007). These favourable traits are (partly) passed to their offspring and will therefore become more dominant in the next generation. The idea that the most successful variant of a trait becomes dominant in a population by genetic inheritance is known as Darwin’s theory of evolution by natural selection (Freeman & Herron, 2007).
Because different rice species grow under different conditions, dominant traits differ between species and a wide genetic variation exists. As salinity is becoming an increasing threat worldwide and rice is inherently sensitive to salt stress (Rahman et al., 2016), research is conducted to explore the genetic variation for salt tolerance. One of the genes found to be associated with salt tolerance in rice is Saltol (Thomson et al., 2010). Saltol controls Na+/K+ homeostasis in the shoot and thus the accumulation of sodium in the cells. Rahman and
colleagues (2016) found variation in salt tolerance between rice accessions with different alleles at the Saltol locus. Because rice species show natural variation in genes associated in salt tolerance, like Saltol, some rice species are more salt tolerant than others. This natural variation between different species is the foundation of plant breeding and genetic modification of plants.
2.5 Climate resilience theory
The concept of climate resilience can be addressed to achieve less soil degradation by salinization, and thus to improve rice productivity. The climate resilience theory (Nelson, Adger & Brown, 2007) shows how the agricultural sector, in this case the Senegalese farmers, is able absorb stresses, such as salinization and increasing drought events. By combining the data from this research paper with the theory, the weak spots in the climate mitigation and adaptation strategies of Senegal can be determined. With the aid of the climate resilience theory the ability of farmers to adapt to salinization will be researched.
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3. Methodology
A DPSIR analysis is conducted on the complex salinization problem in Senegal. The DPSIR framework, perfected by the European Environment Agency (EEA) programme and adopted worldwide, is used to give insight into a specific problem by structuring causal links and enabling feedback to response on different aspects (figure 3) (Gari, Newton & Icely, 2014). It is a framework used to structurally analyse environmental problems, analysing socio-economical environmental systems (SES). The problem will be analysed from cause to impact, describing interactions between society and the environment. This chain of causal links, the DPSIR-framework, is structured as following: starting with the driving forces (D), through pressures (P), which influences the state (S), which in turn has an impact (I). A response (R) can be formulated to change these different aspects of the causal link (Kristensen, 2004).
The drivers are defined as ‘a need for human beings, the industrial sector or a nation’, and can be both primary and secondary (Kristensen, 2004). The resulting pressures are the driving forces of human activities that lead to meeting this need, and thus exert pressure on the environment. The pressures can be divided into three types, which are caused by production or consumption processes: excessive use of environmental resources, changes in land use and emissions of chemicals, waste, radiation and noise to air, water and soil. By ‘state’ the combined physical, chemical and biological conditions of the environment are meant and the quality of the various environmental compartments in relation to their functions. The state of the environment is affected as a result of the pressures. The changes in the state have an impact on the functioning of the ecosystems, their life-supporting abilities and ultimately on human health and economic and social performance of society. A response is an answer to this undesired impact, which can either affect the driving force, pressure, state or impact to change the causal link and resolve the issue of the undesired impact (Kristensen, 2004).
The DPSIR framework facilitates an interdisciplinary view on the theories of the different disciplines as it gives insight in both the socio-economic and ecosystem aspects of a problem. For example, plant engineering for salt tolerance could theoretically improve rice yield. However, in order to achieve an increase in self-sufficiency, taste preferences of the population, possible social resistance towards GMOs and (inter)national GMO legislation should be taken into account.
Although DPSIR is a widely used method to analyse environmental problems, it has received some valid criticism. EEA advises to take into account the complexness of reality, alerting to the need to carefully and accurate define the five categories (Gari, Newton & Icely, 2014). Another critique is the absence of change in dynamics in the DPSIR framework as the DPSIR sets certain stable indicators as the base of the framework. This makes it necessary to conduct the same analysis over regular intervals to assess the effect of the implementation of certain responses on and the change in the SES. A third criticism is that the simplification of the complex problem that exists in the SES can overlook relations between the categories as a consequence, ignoring synergetic relations that are common in nature (Gari, Newton & Icely, 2014). One of the most compelling critique on the DPSIR method is the issue of power and privilege determined in the framework. The DPSIR framework does not explicitly mention power structures and mostly only a small group can implement responses effectively; the top of the hierarchy formed by national governments, supranational organizations, and international organizations (Carr et al., 2009). Since power relations are mostly ignored, political aspects need to be added to give a proper insight in the problem. Nevertheless, DPSIR still functions as a good framework structuring a complex problem in clear sections, making it translatable and understandable for stakeholders.
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Figure 3 DPSIR model used as a backbone for the research. Retrieved from Kristensen, 2004.
To construct the DPSIR analysis a distinguishment between primary data and secondary data is made. Primary data used consists of an interview with the Senegalese Institute for Agricultural Research on how to raise productivity. This interview will give a more accurate view of the problem and provide a future scenario. Secondary data will consist of a literature review, using policy documents of the Senegalese government, intergovernmental organisations and non-governmental organisations. Also, scientific articles and review articles will be used. Next to a literature review, a GIS-analysis focussing on areas in Senegal affected by pressures that enhance salinization of the soil will be conducted. Datasets from ESRI and the Ministry of Agriculture and Rural Development will be used to perform this analysis. The aim is to provide schematic, overviewing maps of areas at risk.
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4. Results
The results of this research papers will be presented by the usage of the DPSIR model (figure 4), explained in the previous paragraph. While analysing food security in Senegal, a focus is placed on the rice production, as this is an important crop there.
Figure 4 Results structured via DPSIR analysis. Authors, 2017. 4.1 Drivers
4.1.1 Population growth & urbanization
Senegal has had an average population growth of 3.1 per cent per year in the years 2010-2015 according to the UN (UN data, 2017). The natural increase is positive, as the amount of births exceed the amount of deaths. As is shown in figure 5, the population pyramid of Senegal is expanding. It shows high birth rates and a rather young population, which means the population is expanding. Population growth is a driver and causes several pressures. A larger population means that there is more stress on food, water, energy and land. The agriculture sector needs to keep up with the growing demand of the growing population.
Increasing urbanization leads to an increase in demand for rice, since the people who move from a rural area to the city cannot provide food through production for themselves, and need to buy food instead. In urban areas the imported rice is more prevalent than the locally produced rice (Lançon & Benz, 2007).
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4.1.2 Lack of knowledge
The application of irrigation schemes can be rewarded with potential high yields. However, if these schemes are applied incorrectly they can cause economic loss and have impact on the environment and human health. Surveys conducted under farmers (Manikowski & Strapasson, 2016) showed that farmers are not aware of these possible risks, and thus prevent constructing a better, and more resilient system.
4.1.3 Rice preference
Rice became an important staple food in Senegal during the colonial era, when they started importing cheap rice from other French colonies in South- East Asia (Rizotto & Demont, 2010). They imported rice instead of producing it themselves so that the focus could be on the groundnut sector in agriculture, which was a profitable export product at the time.Nowadays rice is still an important staple food of the Senegalese diet. However, the population has a preference for the taste of imported aromatic broken rice from Asia over the domestically produced rice (Diagne, Demont & Ndour, 2016). Moreover, local rice is perceived as being of lower quality than imported rice (Rizotto & Demont, 2010).
4.2 Pressures
After literature research it was found that three pressures are responsible for increased soil salinization: climate change, applied irrigation schemes and the construction of two hydropower dams.
4.2.1. Climate change: weather extremes and droughts
Giannini, Biasutti and Verstraete (2008) researched the shift in climatic conditions in the Sahel region. They found that between the 1950s and 1960s a change from abundant rainfall to drier conditions occurred. This trend continues, as the Intergovernmental Panel on Climate Change (IPCC, 2012) states that West-Africa will experience more severe droughts in the future. Global warming is also expected to generate climate extremes (Coumou & Rahmstorf, 2012). Higher temperatures will give a higher evaporation rate, drying out the soil surface. This will then enhance the drought event. On the other hand, warming can also result in intense precipitation events, as warmer air has a higher moisture content. This is a possible threat to the rice production in Senegal. D’alessandro et al. (2015) made an overview of the most extensive weather extremes in the period 2000 to 2012. With the aid of this data maps of the impact of the last events were created, using ArcGIS (figure 6). The figure shows that during these events a large number of provinces of Senegal is affected.
Figure 6. Pressures by climate on salinization Senegal. Affected provinces shown in red. Authors, 2017 (Data used retrieved from D’alessandro et al. (2015))
Excessive rainfall, as illustrated in the middle map of figure 6, can have severe impact on agricultural practices. In the period 2014 to 2015, precipitation was irregular at the start of the growing season, delaying planting of the rice. However, at the end of the season extreme precipitation events occurred, damaging the crop (USDA Foreign Agricultural Service, 2015). Weather extremes and droughts are expected to increase salinization of the soil, since evaporation of water is facilitated. When evaporation rates increase, salts are left behind on the surface, thus increasing the salinity of the soil and affecting overall soil quality. Therefore, these changing climatic conditions can be objectified as a pressure.
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4.2.2. Irrigation schemes
Incorrect application of irrigation schemes is also a pressure on the state and result in an increase of salinity levels in the soils. Wopereis, Ceuppens, Boivin, Ndiaye and Kane (1998) did research on soil quality affected by irrigation in the Senegalese River Valley. Surveys conducted under local farmers showed that the soil of non-drained irrigation schemes has become saline, forcing farmers to abandon their fields after a few years. When an area is irrigated, the dissolved salts are not taken up by the crop, and remain in the soil. Additional water is needed to leach these salts from the soil. When drainage is not applied, the salts will accumulate in the soil, damaging the crop. To reduce salinization in rice fields, it is thus important to apply drainage (Ceuppens & Wopereis, 1999). However, this solution is not always clear and logical to farmers due to lack of knowledge on the topic.
4.2.3 Construction hydropower dams
Another pressure put on the state is the building of two hydropower dams: the Manantali dam located upstream in Mali and the Diama dam at the mouth of the river in Senegal (figure 7). The dams were built in the 1980s with the aim to produce 800 GWh per year, reducing flooding events and create a regular water supply for the irrigation of crops (Dumas, Mietton, Hamerlynck et al., 2010). When focussing on rice production, due to drier conditions in the entire Sahel region, rain fed crops are not economically efficient.
The construction of the dams seemed like a good solution to increase rice productivity and self-sufficiency. It was thought the dams would supply freshwater for Dakar, capital of Senegal, and a year round flow for irrigation purposes (Degeorges & Reilly, 2007). However, the observed results did not match the expected results. Firstly, the economic benefits of the dams were not sufficient, since a 38 million dollar loan, provided by the World Bank, was needed to finance the installation and operation of the dam’s turbines (Pottinger, 1997). Secondly, flooding events were reduced from four months to two weeks (Bosshard, 1999). Sedimentation of the river plains by flooding is necessary to keep soils fertile and irrigated (Dumas et al., 2010). Thirdly, it turned out that the production costs of irrigated land were too expensive. The planned costs were between 25.000 and 40.000 US dollars per ha to construct large-scale irrigation networks (Bosshard, 1999). However, actual costs were much higher, resulting in only 100.000 ha instead of the planned 375.000 ha. Furthermore, there were organizational, technical and operational problems
Next to not making the expected results, the construction of the dams caused degraded soil to be exposed to increased salinity. Intrusion of seawater upward the river is strengthened by the lower discharge rates of the river caused by the placement of the dams. In this way, the saline water is not flushed out of the system, and the saltwater table is rising. Since groundwater is used more extensively due to the growing population, the extraction rate is relatively high. Combined with the intrusion, the groundwater now only has a thin freshwater layer, overlying the higher salt water table (Dumas et al., 2010).
4.3 State
Change of the state of salinization by the previously discussed pressures has effect on the soil quality, microbe-plant interaction, microbe-plants in general and agriculture.
Figure 7. Location Manantali dam and Diama dam. Retrieved from Dumas et al., 2010.
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4.3.1 Soil quality: salinization
Thomas and Middleton (1993) define soil salinization as ‘the concentration of salts in the surface or near-surface zones of soils’. A decline in crop yields, and in some cases even complete loss of land for agricultural purposes, can be the result. Figure 8 shows the extent of the areas affected by salt in Senegal in 2015. As pressures such as climate change, wrongly applied irrigation schemes and the construction of the two hydropower dams are still there and increase, the affected areas will grow, further downgrading the state of the soil.
Figure 8. Areas affected by salt. Retrieved from Diack, Diop and Ndiaye (2015)
4.3.2 Plants and agriculture
Salinity is a problem for agriculture because most crops do not grow well on saline soils. Plants signal salt stress when the concentration of Na+ is so high that it inhibits normal cell processes . In saline soils, the difference in
ion concentration at the root-soil interface causes high osmotic pressure in plant cells (Taiz, Zeiger, Moller & Murphy, 2015). Plants cells at the root take up Na+ and Cl- ions and simultaneously water diffuses out the cells in
order to diminish this osmotic pressure. These processes results in two primary effects of soil salinity: water deficit and sodium toxicity. Sodium toxicity disrupts nutrient uptake and growth is reduced because an accumulation of sodium also interferes with photosynthesis processes. Due to these combined effects, crops do generally not grow well on saline soils.
Previous research shows that the yield of agricultural crops decreases linearly with increasing salt concentration (Maas & Hoffman, 1977). Zeng and Shannon (2000) studied a rice yield under different levels of salinity and found a reduction of rice yield at a salinity level of 3.4 dS/m and higher. As a large part of the rice production in Senegal is located on naturally saline soils, the farmers have to deal with these effects.
4.3.3 Microbe-plant interaction
As microbial communities largely reside in the upper layers of the soil, salinization near the surface may affect these communities greatly (Yuan et al., 2007). When soil salinity increases, a significant negative exponential relation between electrical conduct and microbial biomass in carbon is found, concludes a study conducted on a sugar estate in Zimbabwe (Rietz & Haynes, 2003). In Senegal, where salinity in the soil has increased greatly over the years, microbial biomass should follow the same trend. With this reduction in microbial biomass, soil organic matter decomposition and mineralization of inorganic nutrients occur at slower rates. Salt stress could result in a shift in microbial community structure towards prokaryotic microorganisms, as fungi are sensitive to higher salt content. This, however, could also be an indirect effect of vegetation loss by salinization: taking away an important energy source for saprotrophic micro fungi, organisms that feed on dead material (Sardinha et al., 2003). Another concern is the known negative effects of salinization on nodulation and nitrogen fixation by microorganisms (Tilak et al., 2005). However, different studies have observed increases and decreases in mineralization of C and N with increasing salinity, according to Yuan et al., so more research is required (2007).
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4.4 Impact
The state of the SES in Senegal concerning rice production as changed by pressures forming from human set drivers. These changes in states aspects like soil quality, plants and agriculture and plant-microbe interaction have an impact on the wellbeing and health of the people of Senegal. In the following chapter, the effect of these state changes on the food security in Senegal are stated.
4.4.1 Food security: dependency on rice import
Salinization has an impact on food security since it decreases the yield of the rice production. This would affect several pillars of the FAO definition on food security. First of all, the availability of rice would decrease, since there is a less reliable and less consistent source of quality food. Secondly, the access pillar would also diminish since the resources to produce food deteriorate. People would have less access to locally produced rice, since there would be less of it on the domestic markets. Third, the stability of the food production would decline, because salinization is part of a production process that is not sustainable over time. Lastly, the utilization of the rice remains the same, people would have the same knowledge and basic sanitary conditions to choose, prepare and distribute food in a way that results in good nutrition.
Following the entitlement approach, the production-based entitlement decreases in the rural areas, since rice production decreases. The trade-based entitlement decreases for people who cannot produce themselves but do buy the locally produced rice. They would have to transfer to buying imported rice instead of locally produced rice. However, not in all regions the imported rice is available. Mostly rural areas are at risk of this decrease in entitlements. If local production decreases, more import is needed to keep up with the demand. This makes the population as a whole more vulnerable as it increases the dependence on the global market and its prices.
To analyse the access domain of the food security according to the FAO, an important factor is the price of food. Within the entitlement approach price of food is a subsector of the ‘trade entitlement’; if the price of food is too high, the entitlement disappears since the population cannot acquire the food (Devereaux & Berge, 2000). The domestic price of rice is largely influenced by the world rice market, since Senegal is a net importer of rice. A reason for this is that the domestic production of rice does not meet Senegal’s consumption needs. In the colonial period (before 1960) the agricultural production efforts were driven towards production of groundnuts as an important cash crop, to the detriment of rice and millet production (Diagne, Demont, Seck & Diaw, 2013). These were imported from Indochina as cheap staple food (Lançon & Benz, 2007).
After the decolonization in 1960 the state intervened in the agricultural sector, expanding and supporting among others the rice sector (Oya, 2006). The withdrawal of the government from the agricultural sector in the 1990s caused a period of decrease of rice production (from 1993 to 1988), as seen in figure 9. The rise of imports in Senegal was directly related to imports liberalization by the government in this same time period (Lançon & Benz, 2007). However, the rice demand increased, due to the fact that rice dishes are cheaper than millet based dishes, population growth with increasing urbanization, increase in income and changing consumer habits.
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Figure 10. Imported rice as a percentage of the demand (Oteng & Sant'Anna, 1999; Sylla, 2014).
Another cause for such high import numbers is that Senegal imports almost exclusively “100% broken rice” with an increasing preference for aromatic broken, a type of rice the local rice industry is not able to provide (Diagne, Demont, & Ndour, 2016). The Senegalese consumers have a certain preference in taste for broken rice coming from South-East Asia (Oya, 2006) as the French colonizers imported this as a cheap staple food from their other colonies. The domestic rice markets are also segmented on a spatial basis, since imported rice dominates in major urban centres’ markets while local rice is mainly distributed in rural areas and smaller towns (Lançon & Benz, 2007).
Since import is such an important aspect of the food supply in Senegal, the country is highly dependent on the international market (Diagne, Demont, Seck & Diaw, 2013). The fluctuation of the price on the international market influences the price of the domestic food market heavily (Lançon & Benz, 2007). The change in price can negatively influence the access, availability and stability domains of food security. The international food crisis in 2007-2008 caused high prices on the international market, and thus high prices and less availability of rice on the domestic market. This lead to violent food riots in Senegal (Diagne, Demont, Seck & Diaw, 2013). This crisis reaffirmed the inherent volatility of the international markets and reinforced the extent to which food markets have become highly interdependent, and highlighted the inability of national government to deal with dramatic surges in the food prices (Berazneva & Lee, 2013).
The trade relationship between Western organizations and Senegal has not been an equal power balance, seen as the World System Theory. The World Bank and IMF have imposed policy reform packages associated with structural adjustment loans (Washington Consensus) on Senegal and this liberalized the trade and domestic agricultural markets (Lançon & Benz, 2007). Withdrawal of the government from domestic rice production caused a downturn in the sector, meanwhile export to Senegal became cheaper and easier (Oya, 2003). Senegal became thus more dependent on rice import and domestic rice production decreased, which both was not beneficial for food security.
4.5 Response
4.5.1 Resistant rice cultivars
AfricaRice developed three new rice varieties (Sahel 177, 328 and 329) that could match the market preferences
to stimulate local rice production in Senegal (Diagne, Demont & Ndourc, 2015). As the new varieties are specifically developed for Senegal rice farmers, their ability to tolerate salt stress is important. Field studies concerning the salt tolerance of the three aromatic Sahel varieties have not yet been conducted. Neither have genetic studies to the known genes involved in salt tolerance. However, Djaman and colleagues (2016) did compare the effect of different fertilizing policies on the yield of the three different varieties on a saline soil (electrical conductivity of 20 dS/m) in Senegal. The yield of Sahel 177, 328 and 329 under saline conditions was comparable when no fertilizers were used. However, in both the hot dry season as in the wet season the highest yield under nitrogen and phosphorus fertilizers was reached with Sahel 177, followed by Sahel 329. A
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comparable highest yield was reached with Sahel 329 when fertilized with potassium (K) in addition to nitrogen and phosphorus. Fertilizing with potassium in saline environments makes sense, as it is an essential macronutrient which uptake is reduced by Na+ (See Taiz et al., 2015). Overall, Sahel 329 performed best. A
cautious conclusion can be made that Sahel 328 seems least fit to be produced under saline conditions. However, specific research to salt tolerance of the three varieties is needed.
There are more opportunities to further genetically improve rice cultivars for Senegal. AfricaRice, the developer of Sahel 177, 328 and 329 uses selected genes to implement resistance to abiotic stresses in rice varieties (Kumashro et al., 2013). The main salt tolerant gene that AfricaRice uses is Saltol. Saltol is derived from the cultivar Pokkali, known to be salt tolerant (Dramé, Manneh & Ismail, 2013). It is already implemented in rice varieties, like Sahel 108. The Saltol gene is located at chromosome 1 of Pokkali and study of Thomson and colleagues (2010) revealed that it increases salt tolerance by controlling Na+/K+ homeostasis. As mentioned
before, Na+ can compete with K+ on transport into the cell. Saltol could be an interesting gene to improve the salt
tolerance of the aromatic Sahel varieties.
4.5.2 Growth-promoting rhizobacteria (PGPR) phytoremediation
Salinity is a key factor in the reduction of crop yield in Senegal. While the possibilities of developing salt-tolerant crops are well researched, microbe usage proposes an alternative strategy (Dodd & Pérez-Alfocea, 2012). Commonly used fertilizers like Nitrogen- Phosphorous-Potassium fertilizers (NPK- fertilizers) are known to only improve yield for a limited amount of years, over time resulting in the degradation of soil like base saturation and acidification. Their cost and other constraints avert farmers from using them in recommended quantities and times (Rangarajan, Saleena & Nair, 2002; Tilak et al., 2005). Organic matter counteracts these negative effects, improving microbes in the soil to a large degree.
Studies have shown that the implementation of adequate microbial community to the soil ecosystem, known as growth-promoting rhizobacteria (PGPR) phytoremediation, improves soil quality, soil health, plant growth, crop yield and quality of crops (Singh et al., 2011). These bacteria highly promote plant growth under salt stress by increasing the plant's’ tolerance to salt as well as its tolerance to drought conditions which applies to the environment of Senegal (Gerhardt et al., 2017). This increase in growth has a positive effect on the inherent microbial composition in the soil. This boost to the rhizosphere allows for high productive processing of salt ions. PGPR phytoremediation has several advantages over physical and chemical remediation as it preserves the natural properties of soil; it acquires energy mainly from sunlight; high levels of microbial biomass in the rhizosphere can be achieved; and it is low in cost (Huang et al., 2004b, in Zhuang, et al., 2007). Greenhouse studies with a similar climate to Senegal have proven the effectiveness of PGPR phytoremediation, using soils from Southern Ghor in Jordan, a field study in the Khorezm Region of Uzbekistan also showed promise (Gerhardt et al., 2017).
However, there are some setbacks in PGPR phytoremediation. Studies in greenhouses do not always translate well to field experiments, reality having different conditions factoring in. Beside different conditions, it is difficult to assess the extent of effectiveness of phytoremediation in field, creating also difficulties in determining the time until successful phytoremediation. Research about phytoremediation is still scarce (Rangarajan, Saleena & Nair, 2002). In addition, appliance needs to be executed at optimal conditions for the establishment of the microbes to be successful, as microorganisms are effective only when suitable and optimum conditions for metabolism are met and the application scope is limited as existing plant growth promoting rhizobacteria can only colonize on certain plants (Zhuang, et al., 2007). It is therefore important to educate Senegalese farmers on how to conduct phytoremediation accordingly; providing lessons and workshops in the practices and limitations of phytoremediation. Furthermore, when possible, native species (plant and microbes) should be chosen to undertake phytoremediation with.
4.5.3 Sustainable agriculture
Sustainable agriculture has gained in popularity over the last years. This is partly contributed to the increasing realisation that conventional agriculture will result in less desirable outcomes like reduced crop yield or higher costs (Singh et al., 2011). Efficient soil microbial biota implementation is only sufficiently applicable for sustainable agriculture practices (Zhuang, et al., 2007). Whilst the improvement of soil quality by the utilisation
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of microbe’s shows promise, risks associated with the implement of nonindigenous species need to be recognised. The possibility of invasiveness exist: the use of foreign species to enhance the soil quality can lead to a change in dynamics in an ecosystem system and in ecosystem functions, thriving over indigenous species, being chosen due to their heightened ability to survive in the conditions of the ecosystem (Wolfbarger and Phifer, 2000). Few introduced species become invasive, however it is important to realise the possibility. This applies for natural occurring species and genetically engineered species.
4.5.4 Improvement irrigation schemes
To reduce the pressure by wrongly applied irrigation schemes an important response is to improve these practices. Managing soil salinity can be done by drainage and by addition of organic matter to the soil. Rice fields should be permanently flooded to ensure high production. Adapting irrigation schemes results in salts being able to leave the soil. Permanent drainage of the rice fields reduces accumulation of salt in the soil and surface water by evaporation. IRRI (2017) states that the rice sector is a massive consumer of water, because the permanent flooding uses 2.5 times the amount of water needed to grow maize or wheat. Senegal might face water scarcity in the future due to increasing drought. Therefore it is necessary to use the water sustainably, meaning the construction of ridges and furrows to make sure that the water can re-enter the hydrological system. By doing so, soil quality is also maintained, since less water evaporates, leaving salt behind in the soil.
While looking at increasing rice productivity another measure to implement while improving irrigation schemes would be the addition of organic matter to the soil (International Center for Tropical agriculture(CIAT); Bureau for Food Security, United States Agency for International Development (BFS/USAID), 2016).. This increases nutrient availability and decreases the exposure to climate risks as it optimizes plant development. 4.5.5 Education on irrigation
Education on proper irrigation is a response to the pressure of wrongly applied irrigation schemes in rice fields. As incorrect practices can lead to a higher salinization rate of the soil, it is important to educate farmers about the possible dangers. As stated in the pressure section of this research paper, Manikowski & Strapasson (2016) have found that farmers are often not aware of the possible risks of lack of drainage of the rice fields. Together with climatic pressures, such as increasing droughts and precipitation, it is important to become more resilient to salinization in order to secure rice production. To increase future rice production, the quality of the agricultural land has to be maintained.
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5. Discussion
Increasing salinization has a negative influence on the local rice production in Senegal as it decreases the maximum possible yield. And while rice, as a preferred staple food, appears to be a very efficient crop in battling food insecurity in Senegal, it also plays a large role in the salinization of the soil. There seems to be a reinforcing feedback loop in which rice production (stimulated by local demand) increases salinization which causes lower rice yield. This lower yield results in an increase in agricultural land needed for rice production, which further causes salinization. In this way, striving to become self-sufficient in rice could be detrimental. However, by changing irrigation schemes the pressure of bad irrigation on agricultural lands could be reduced or even prevented. This intervention in the system could break the feedback loop of rice production and increasing salinization. If the Senegalese government wants to proceed with, and achieve success in, the self-sufficiency plan it is necessary to implement responses which deal with the salinization as a result of the rice production itself. Since this research aims to improve the PRACAS plan of the Senegalese government, providing a future scenario is helpful. In the methodology section an interview with the Senegalese Institute for Agricultural Research on how to raise productivity was planned as primary data to achieve this goal. Unfortunately, communication issues occurred, resulting in the interview being cancelled. After conducting a literature research on government plans to increase rice production in Senegal, the concept ‘climate-smart agriculture (CSA)’ shows promising results (CIAT & BFS/USAID, 2016). The concept aims to combine agricultural development and climate responsiveness. For rice, several suggestions are being made to increase production, while improving the country’s climate resilience. Water-efficient irrigation techniques, certified short-cycle varieties and management of soil salinity by drainage and flooding of the land and the addition of organic matter to the soil are stated as key CSA technologies. This is in line with the response section of the DPSIR model of this research paper.
Not only salinization causes a negative influence on the local rice production however. Other factors which are not described in this paper can also have an effect. For example droughts and extreme weather can also affect the harvests besides its effect on salinization, agricultural land being used for other purposes, urbanization, and even increase in early return from the migration north of the black-tailed godwit (Limosa
limosa), who then eat the just sown rice and thus decreases rice yield (Doornebal, 2017). These are factors that
the Senegalese government has to take into consideration to achieve complete self-sufficiency regarding rice production.
6. Conclusion
Through answering the sub questions with the DPSIR analysis the main question can be answered: ‘How does
salinization influence the rice production, and thus the food security in Senegal?’.
What causes the salinization of the soil in Senegal? As the DPSIR framework has shown, the salinization is caused by several drivers; Population growth and urbanization, lack of knowledge by the farmers, and the population’s rice preference. These drivers have impacts on the state, which are known as pressures: wrong use of irrigation schemes due to the lack of knowledge, climate change which causes weather extremes and droughts, and the construction of hydropower dams.
How does salinization affect the rice production in Senegal? Here the impact of the state change to increasing salinization on the rice production and thus food security is shown. As salinization decreases rice yields, more import is needed which makes the country increasingly dependent on the price of rice on the world market. Also food security decreases, as the availability, stability and access to rice decreases.
What can be done to improve rice production and thus food security in Senegal? Here the responses from the DPSIR model come into play. To decrease the driver ‘lack of knowledge’ and pressure ‘wrong use of irrigation schemes’ there is the response ‘education on irrigation’, which can be implemented in the PRACAS self-sufficiency plan by the government, which educates the farmers. To decrease salinized soil and is thus a response to the State, growth-promoting rhizobacteria (PGPR) phytoremediation is an option. Sustainable agriculture can also enhance the soil quality. Salt-resistant rice cultivars and GMO’s are response options that increase rice yields and thus decrease the impact on food security.
These responses could be implemented in the self-sufficiency plan by the Senegalese government, to decrease the effects of salinization and ensure an increase in food security.
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