From experiment to market development: A case study of prospects and value chain of saline agriculture in Terschelling, the Netherlands

ABSTRACT

Saline agriculture, understood as production of food and biomass on salt-affected soils, also including adaptive soil, water and crop management, is a promising climate-adaptive strategy. However, it is difficult to create a dedicated food chain and to develop a business model in the North Sea countries. This study aims to explore whether islands can be an incubator for saline agriculture by looking at a saline agriculture initiative on Terschelling, the Netherlands, which focusses on the touristic niche market. We conducted semi-structured interviews to map the value chain on the island and identify opportunities and constraints for its development. Drawing on the innovation theory, we analyse to what extent small islands can be considered a favourable niche for sustainability innovations such as saline agriculture. Our results confirm the potential for production and marketing of local saline food specialities on Terschelling, although the market and value chain still require further development. The potential of this initiative is considered positive, although at this stage external support is needed in the form of voluntary labour or subsidies. We conclude that islands are a favourable niche for the introduction saline agriculture as such island initiatives can be a stepping stone for a wider introduction of saline agriculture as a climate adaptive strategy.

KEYWORD:

• Saline agriculture
• climate change adaptation
• halophytes
• tourism
• islands
• innovation

1. Introduction

Salinization is one of the most common soil degradation processes and constitutes a major threat to the global resource base (Gould et al., 2021; Hassani et al., 2021; Teh & Koh, 2016). Although the exact extent is difficult to determine, it is estimated that around 10% of the global arable land is affected by soil salinity or sodicity (Zaman et al., 2018). Food security concerns and the scarcity of new agricultural lands emphasize a need to improve use and productivity of degraded lands (Qadir et al., 2014). Moreover, salinization also affects freshwater availability, which is already a major limiting factor to sustainable agriculture (Ladeiro, 2012). Therefore, addressing salinization while preserving freshwater resources is crucial in achieving food security (Zaman et al., 2018). Climate change is likely to exacerbate the problem of salinization through more severe droughts and sea-level rise, leading to more frequent flooding and (combined with excessive groundwater exploitation) increased saline seepage (Oude Essink et al., 2010). Many coastal areas worldwide already suffer from salinized groundwater systems (Colombani et al., 2016; Oude Essink et al., 2010).

Saline agriculture, the cultivation of crops using saline water and soil, forms a promising adaptive strategy (Ladeiro, 2012). It includes both the cultivation of halophytes and traditional freshwater crops with enhanced salt tolerance (Ladeiro, 2012). Saline agriculture opens up new water sources, such as seawater, brackish water and possibly treated wastewater, e.g. used irrigation water (Ladeiro, 2012; Miller, 2006; Shimron, 1994). Although saline environments are generally lower yielding, adapting agriculture to these conditions enhances the overall availability of resources for food production (De Vos et al., 2016). Moreover, several halophytes, such as Salicornia or Sesbania, have potential for soil rehabilitation, as they can reduce the salt content over time (Hasanuzzaman et al., 2014; Karakas et al., 2020).

Despite being commonly applied in North Africa and the Middle East, saline agriculture is currently still marginal business in the North Sea region (Vellinga et al., 2021). On the Wadden Sea islands along the northern coast of the Netherlands there are a few initiatives exploring the feasibility of saline agriculture (De Wit et al., 2021). De Zilte Smaak, the only initiative which focusses on the local tourist market is located on the island of Terschelling. At the same time, the waterboard on Terschelling has signalled an increased attention for salinization, as some farmers notice a decreased productivity on their lands (Hamstra, 2020, personal communication, 9 September 2021). Despite these signals, most farmers hesitate to adapt their farming practices to salinisation. Their call for measures to improve fresh water supply is the dominant response (Janson, 2021) even when it is known that there are technical and financial limits to the fresh water supply. Some policy makers and research funding agencies recognize the need to investigate saline agriculture prospects and a potential value chain. On the island of Terschelling a group of forward-looking citizens and recreation entrepreneurs with support of researchers have taken the lead by starting with field tests in one of the most salinized areas of a Terschelling polder.

The goal of the study is to explore the viability of this initiative in terms of agricultural production and in terms of marketing. Experiments are carried out with various soil management techniques and various crops and processing and marketing methods. The aim is to identify the best options for the saline production and consumption on the island in a commercial setting. This paper describes an important part of the research initiated to support the goal of the initiative. The central research question addressed is: what are the prospects for the development of the value chain for saline agricultural products on Terschelling? It is followed by two sub-questions:

1. What is the current value chain for saline agriculture and its products on Terschelling?

2. What trends can be perceived regarding the future development of saline agriculture?

This paper contributes to literature by analysing a number of geographically specific aspects, opportunities and barriers for a transition from traditional freshwater to saline agriculture. A multi-level perspective is applied to identify and analyse the transition aspects (Geels, 2002). Data are provided through a case study, with a focus on value chain mapping. Semi-structured interviews are carried out to clarify the findings. Finally, we explore the question whether islands, due to some specific characteristics, can serve as an incubator for saline agriculture in other areas.

2. Theoretical framework

This paper builds on the multi-level perspective (MLP) as described by Geels (2002). A rich body of literature applies the MLP as a transition framework to analyse drivers and barriers of change in sustainability transitions in the agro-food system, including, for example, organic and conservation agriculture. This research generally focusses on the production stage, while processing, distribution and consumption remain understudied and linkages between production and consumption are overlooked (El Bilali, 2019). As the presence of a well-functioning value chain is an important condition for economic viability (Zamora, 2016), our study covers the stages of production, processing, distribution and marketing and retail.

2.1. The multi-level perspective

Transitioning towards saline agriculture involves more than a change in agricultural practices. The scaling of agricultural innovations, such as saline agriculture, is influenced by complex interactions between biophysical, social, economic and institutional factors (Wigboldus et al., 2016). The MLP helps to identify both drivers and barriers of change on three different levels. The first level presents the slowly evolving cultural trends that are usually technology-external trends. The second level is the sociotechnical regime. The regime is relatively stable due to the interdependencies between different regime actors, which are reproduced in their activities. The regime is focussed on incremental innovation and its dynamic resists transformative change. On the third level we find the sociotechnical niches. These are protected environments where normal (market) selection criteria do not apply and radical innovations can develop. They are a space for learning processes and the formation of the social networks supporting an innovation (e.g. supply chains and user-producer relationships). It is the alignment of developments on these three levels (Geels, 2002) that determines the success of an innovation: successful developments in the niche that align with pressures from the landscape and (subsequent) changes in the regime (Geels, 2002). In the next sections we will analyse the current regime of freshwater agriculture and explore the potential of islands to serve as a sociotechnical niche for saline agriculture to develop.

In this research, the term niche product is used for a product with a certain attribute that enhances its value and meets consumer preferences within a specific, small market segment (the niche market). For agricultural products, examples of such attributes are local, organic or environmentally friendly products. These attributes can be used for product differentiation. They distinguish a certain product from other products, making it more attractive to a specific target market (Loureiro & Hine, 2002).

The concept of the value chain is originally introduced by Porter (1985) and originates from the concept of the supply chain (Zamora, 2016). However, supply chain thinking has a strong focus on costs, margins and market shares and is more suitable for commodities. The concept of the value chain puts more emphasis on the value that is added to a product at each stage through differentiation of the product (Zamora, 2016). It is therefore more appropriate for the analysis of differentiated niche products such as the saline products produced on Terschelling.

Two types of value creation activities are distinguished in a value chain: primary activities, which directly contribute to the value of the product, and secondary or support activities, which enable and improve the performance of primary activities. A value chain includes different actor groups. Examples of primary actor groups are input suppliers, producers, operators, processors, retailers and consumers. In addition, different technological, business and financial service providers are involved, performing supporting activities (Kumar & Rajeev, 2016). Examples of support actors are credit providers, business consultants or parties providing market information.

2.2. The uptake of saline agriculture

Various factors lock-in the status quo of ensuring continuous freshwater supply to farmers, even at high economic and environmental costs. Innovation has traditionally been focused on optimizing crop production under freshwater circumstances. Saline agriculture produces new foods, for which markets are yet to be created in the Netherlands (De Wit et al., 2021; Saidov, 2016; Vellinga et al., 2021). Consumers might still be too unfamiliar with salt-tolerant crops or halophytes, plants growing on highly saline soils, or fear consuming too much salts. Moreover, freshwater supply is often financed with public money. Agricultural subsidies and the exclusion of environmental costs and other externalities in food prices work in favour of the status quo. Due to this market failure, the regime centred around freshwater agriculture can sustain itself, even when the actual costs of mitigation outweigh its benefits (Vellinga et al., 2021).

A series of field tests have been carried out in the North Sea countries in the years 2017–2021 (Gould et al., 2021). In some of these North Sea countries, salinization is recognised as a threat to agricultural production. However, even in the Netherlands with major agricultural areas below sea level, the urgency to address the issue is relatively low (Beauchampet, 2021; De Wit et al., 2021). Not availability but demand determines the distribution of water, and water management is historically focused on mitigation, investing in increased freshwater use efficiency (De Wit et al., 2021). Historical flooding problems have resulted in a focus on the quick discharge of water, as well as the preference to solve water issues collectively. Complex power relations and strong interdependencies between farmers, water boards, provinces and the central government have institutionalized a “freshwater first” approach (Beauchampet, 2021). However, ensuring freshwater supply will become increasingly challenging and costly in different areas with ongoing global climate change. In order to be prepared for this scenario, experimentation with the production of food, fuel, forage and fibre under saline soil and water conditions deserves more attention (Vellinga et al., 2021).

2.3. Tourist islands as a stepping stone?

Islands are often considered to be favourable niches for experimentation with sustainability innovations, as, for example, renewable energy systems (e.g. Sperling, 2017; Tsagkari, 2020). The impact of global climate change and, specifically, sea-level rise is often more acute and straightforward on islands, leading to a higher sense of urgency (Kueffer & Kinney, 2017; Ratter, 2018). Increased salt-intrusion threatens islands’ already vulnerable freshwater lenses, considering the impossibility to let in freshwater from elsewhere and a high population pressure, in particular on tourist islands (Ratter, 2018). Sea-level rise, storms and changes in precipitation lead to further stress on freshwater availability (Thomas et al., 2020). Due to the heavy reliance of the agricultural sector on this freshwater availability, it is particularly vulnerable to this stress, and climate change is recognized as one of the most important factors affecting agriculture and food security in small island developing states (SIDS) (Thomas et al., 2020).

At the same time, island societies know a long tradition of living within their spatial, ecological and social boundaries. Due to the scarce resources, many islands are particularly interested in sustainable development (Ratter, 2018). Local resources and social cohesion are often of great importance (Kueffer & Kinney, 2017). Moreover, island people developed an understanding of the dynamic nature of coastal environments. This is crucial in being able to respond to environmental threats such as sea-level rise. Islands can therefore help to develop a way of living “”with rather than on our shores’’ (Gillis, 2012; Ratter, 2018). Small island developing states have been successful in advocating stronger international ambitions to limit global warming through the United Nations Framework Convention on Climate Change (UNFCCC), and have also made progress in climate change adaptation and mitigation on a national scale (Thomas et al., 2020).

From an economic perspective, islands cannot reach the same cost-efficiencies as on the mainland due to their limited scale (Ratter, 2018). This increases the need to make use of their favourable location and focus on niche markets, competing on assets like uniqueness, quality and sustainability. The many tourists often present on islands offer an important economic advantage (Ratter, 2018). Indeed tourists might be more willing to experiment in their menu and pay a higher price for special products.

3. Materials and methods

To address our research question and explore the prospects for the development of the value chain for saline agricultural products on Terschelling, we employ the case study method.

3.1. Case study: The island of Terschelling

3.1.1. Location and international North Sea setting

On the island of Terschellig, the Netherlands, a group of local citizens and tourist entrepreneurs took the initiative to grow crops on a salinized piece of land. They were supported by volunteers and received various subsidies. Foundation “De Zilte Smaak” was created to organize the production, processing, logistics and marketing activities. The goal of the organization is to pave the way for commercial saline agriculture activities on the island. The organization joined the EU-North Sea Interreg project SALFAR (Wijbenga, 2021) in 2018 providing access to an international network of projects and experts experimenting with saline agriculture.

3.1.2. Current status of saline agriculture experiment in Terschelling Islands

Farmers located in the polder, mainly dairy farmers, on the island noticed a decreased productivity on their lands (De Vries, 2020). The local waterboard reported an increasing number of questions about salinization in the polder, especially after a number of dry summers (Hamstra, 2020). Figure 1 shows progressing salinisation on the island. The light green area is a polder with controlled water levels. The level of the grassland is at or just below sea level. It is protected from high tides and storm surges by a dike, six metres high (Koster, 1993). The field of De Zilte Smaak is located on a small plot in this polder, right along the dike.

Figure 1. EC_e levels of the topsoil and EC levels of surface waters in mS/cm in the agricultural fields on the south coast of the Island of Terschelling, the Netherlands, adapted with permission from Janson (2021). The light green area is a polder with controlled water levels. The level of the grassland is at or just below sea level. It is protected from high tides and storm surges by a dike with top level of some 6 meters above mean sea level (Koster, 1993). The field of De Zilte Smaak is located on a small plot in this polder, right along the dike.

In response to these challenges, foundation De Zilte Smaak started to experiment with saline agriculture on Terschelling. Crop selection, processing and logistics in a modest way was done in cooperation with local restaurants and tourist shops.

Through De Zilte Smaak initiative the issue of salinization is starting to receive more attention on Terschelling. Furthermore, foundation De Zilte Smaak is not only active in agricultural production, but also in processing, distribution, marketing and retail. Due to these factors, the case study on Terschelling is suitable to explore the fit between saline agriculture and the wider agro-food system.

3.1.3. Salt-tolerant crops cultivated by De Zilte Smaak

The foundation tested a number of salt-tolerant crops and halophytes in the garden. The plants that were successfully cultivated include salt-tolerant potatoes (Solanum tuberosum Violet queen), celery (Apium graveolens var. rapaceum), Salicornia, red and yellow beets (Beta vulgaris), redvein dock (Rumex sanguineus), spring onions (Allium), sea banana (Carpobrotus rossii), ice-plant (Mesembryanthemum crystallinum), oyster leaf (Mertensia maritima), sea fennel (Crithmum maritimum) and mustard cress (Lepidium sativum). Other varieties of potatoes, fennel and tomatoes did not perform well. Hotels, restaurants and catering business expressed interest in Jerusalem artichoke, root vegetables, varieties of brassica, carrots and sea kale. Some plants such as Salsola komarovii were also not tasty enough for the consumption. Salicornia also tended to be too woody for consumption.

4. Research design and data collection

Data collection included participatory observation and semi-structured interviews. The value chain was mapped on the basis of observations over a period of three months of field research. Semi-structured interviews were conducted with experts and stakeholders in order to identify and clarify the various opportunities and barriers in the development of this value chain. Local, national and international experts were identified through the SalFar Interreg network. Stakeholders were selected systematically through the value chain map. Only stakeholders, whose activities were based on the island, were included in the research: two farmers, two retail entrepreneurs, one tourism entrepreneur, three chefs from partnering restaurants and a representative of the local waterboard. See Table 1 for an overview of all interviewees.

Table 1. Overview of interviewees.

Code	Function	Remark
E1	Expert	Specialist saline agriculture; R&D crop cultivation under saline conditions and field implementation
E2	Expert	Senior advisor; integrated coastal zone management
E3	Expert	Director Ökowerk Emden, centre for environmental education and innovation in sustainable agriculture, incl. saline agriculture
E4	Expert	Author of MSc thesis on the scaling of saline farming of quinoa and seed potatoes in the Netherlands
E5	Expert	Marketing and communication expert (field: soil, food and health); program manager for innovative and sustainable business concepts
E6	Expert	Communication and consultancy; specialized in health and sustainability topics
F1	Farmer*	Dairy farmer
F2	Farmer*	Arable farmer, also active in processing and retail
R1	Retail entrepreneur*	Also active in processing
R2	Retail entrepreneur	Also active in processing
T	Tourism entrepreneur*	Also active in processing and retail
C1	Chef
C2	Chef
C3	Chef
W	Representative local waterboard

*member of foundation De Zilte Smaak.

The interviews were conducted with an interview. Interviews were recorded and summarized and a respondent check was conducted. No ambiguous statements from interviewees who did not respond to the member check were encountered, hence no unclarities remained.

4.1. Data analysis

In the analysis of the interview results, recurring topics were assigned a colour code. Topics were marked with this colour in the interview summaries. Subsequently, all identified topics were listed in a separate document, together with all views or opinions interviewees expressed on that topic. These topics were divided per sub research question and structured according to the different stages of the value chain. This document formed the basis for the interview results. Where relevant, results are supported with quotes. Since all but one of the interviews were held in Dutch, quotes have been translated into English by the researchers. Interview data is available upon request.

5. Results

5.1. Value chain mapping

The value chain map for saline agricultural products on Terschelling (see Figure 2) was developed based on observations of logistics and commercial networks on the island.

Figure 2. Present value chain map for saline agricultural products on Terschelling. Dashed actors or linkages were not yet definite at the time of this research. Activities outlined in bold take place on Terschelling.

The results of the interviews are presented following the four stages of the value chain, production, processing, distribution, marketing and retail.

5.1.1. Production

Interviews from stakeholders and experts on the production side clearly reveal that in the coastal areas of the Netherlands commercial exploitation of saline agriculture is still a major challenge. Still, most of the experts stress the need for experiments (E1, E2), especially in view of supporting the international reputation and position of the Netherlands in agriculture and water management (E1, E2, E4) and the fact that salinization is a major world-wide issue (E1, E2, F2).

Interviewees notice a continuous rise in the number of initiatives and availability of subsidies nationally and internationally (E1, E2, F2), including budgets for research (E2, E3, F2). They generally recognize the need for field testing and demonstration. Successful examples will be crucial for a wider acceptance of saline agriculture (E1, E2). Experts recognize the need for innovation (E1, E2, E5). The group of citizens and recreation entrepreneurs involved in De Zilte Smaak mention the need for innovation as the major driver of their involvement (F1, F2, T).

A major dilemma identified among stakeholders is the chicken and egg question. To generate a return on investment in saline agriculture a producer needs a market for the products. But a reliable market requires ample supply of saline grown products (F2). A farmer starting to produce crops on salt affected will have to invest in time and technologies. As a market is not really there it is difficult if not impossible to find private funding (E2, E5, F1, F2). In order to kick-start saline agriculture, dedicated public or philanthropic funding is required (E5) (F1, F2). On Terschelling, the initial investment constraint was overcome with the help of volunteers and EU research subsidies (F1) in particular the EU Interreg North Sea (Gould et al., 2021). Alternatively, farmers could step by step start practicing saline agriculture as a diversified income stream within their own enterprise (E2, F1, F2). This involves less risk than starting a new enterprise (E2) and can help to diversify agricultural enterprises (F1). The availability of entrepreneurial capital could be an important benefit (F1). On Terschelling, some of the board members and volunteers of De Zilte Smaak recognized such a step by step integration into an existing dairy enterprise as a viable future scenario (F1, F2).

Several experts stressed the importance of practical experience in selecting and growing food crops in a saline environment (E1, E2, E3, F2). Saline agriculture is relatively labour-intensive and yields are unpredictable (E3, F2). The identification and testing of more salt tolerant cultivars (E1, E2, F2), including appropriate cultivation and soil management, irrigation and leaching (E1, F1, F2). Stakeholders on Terschelling also point out that soil and hydrological conditions differ significantly between different locations (F2, T). For example, the experimental site on a neighbouring island Texel is characterized by predominantly sandy soils with a relatively low groundwater table (De Vos et al., 2016), while the site on Terschelling consists of a 10–15 cm thick peat layer on top of heavy clay, with a relatively high groundwater table (F2).

The structure of clay soils may well deteriorate under the influence of salt, resulting in poor aeration and infiltration capacity (E1, F2). Cultivating under saline conditions without damaging the soil on the long term remains a challenge (E3). Moreover, salinization is believed to negatively affect soil life, although the exact effects are still unknown (E1, E2). These issues are recognised on Terschelling, where the infiltration and water holding capacity of the soil are poor, resulting in issues with both water surplus and deficiency (F1, F2). Both farmers indeed expect the soil life to change under the influence of salt (F1, F2), although one of the stakeholders emphasizes that he sees this as inherent to saline agriculture: ’’in the end, this project should result in an enterprise working with brackish and saline water. That will never be the best conditions. Our field is located there where we will use the experience that we now build’’, and: ‘’there will be a different soil life, which is not optimal for plants. They will grow slower, that happens in nature too’’ (F1). The local waterboard adopts a rather passive stance towards saline irrigation, indicating that it is not prohibited, mostly because it has never happened before. However, scaling up would raise new concerns, and they need more measurements to understand the effects of saline agriculture on the groundwater system and the effects on neighbouring agricultural lands (W).

The high weed pressure forms another main challenge (F1, F2). The foundation has decided not to use any pesticides (F1, F2), while mechanisation is complicated by the poor soil structure and small scale of the field (F2). These factors add to the labour-intensity of production. Some degree of mechanisation might be possible in the future (F1), although this would require special machinery, as the soil cannot support heavy, regular machines (F1, F2).

5.1.2. Processing

The interviews revealed that the various options for processing the crops provide a range of new opportunities. This implies that processing can add significant value to the product (E2, E3, E5, E6) and can open new markets, until now overlooked (E2). Possibilities include the use of saline crops as a source of protein (E2, E3, E5), herbs (F2, R1) or as substitute for added salt (T, R1), since the salts naturally present in halophytes are believed to be healthier (E1, E2, E5, E6, F2). The further development of processed products, such as pesto and crisps, entails another opportunity. Processed products add value to the fresh product (F1), help to introduce people to new foods and flavours (R2, T) and are preservable, thus providing income year-round (E6, F1, F2). They are believed to have a good market potential (E6, T, R1), which is already visible in the sales of Salicornia crisps (F2, R1). Another strategy to familiarize people with saline vegetables is their use in restaurants, on which all partnering restaurants experience positive feedback from their guests (C1, C2, C3).

However, few processed products have been developed on Terschelling until now (F1). This is recognized as an obstacle in the goal to add value to the produce (F2). The instability of the harvest was mentioned as one reason (R1), but most importantly, the development and testing and market introduction of such products simply requires a lot of time. The time-consuming pioneering character of the work indeed formed a recurring theme during the interviews (…). As one stakeholder explains: ’’I can always come up with new ideas, but I am too busy to implement them. […] We try to do something that is not our normal job, on unsuitable soil and we also try to tap into a market that does not yet exist. So, we do not try just one new thing, but many new things at the same time’’ (R1). Another opportunity affected by time constraints lies in the communication between producers and buyers (F2, T). Restaurant chefs explain that they are flexible enough to use the varying harvest, but that they currently lack up-to-date information on the availability of crops from the foundation (C1, C2). The topics identified here indicate a window of opportunity for the further development of the value chain.

Lastly, experts discussed several characteristics of saline crops which could limit processing possibilities. For halophytes, their high salt content makes them unsuitable for consumption in large quantities (E1). Saline potatoes are expected to be unsuitable for industrial processing due to their smaller size and higher sugar content, possibly causing a brown colour during frying due to caramelisation (E1, F2).

5.1.3. Distribution

The distribution of crops and products is under-developed at the stage of this study. Buyers can currently freely harvest fresh crops from the field in exchange of a yearly donation. Most stakeholders appreciate this system (F1, C1, C3, R2). One chef explains: ‘’I really enjoy it and it is very instructive for the apprentice cooks to come to the field, as they often do not know how vegetables actually grow’’ (C1). At the same time, different stakeholders see switching to selling crops per kilogram as a next step in the development of the value chain (F1, F2, R1, C2). An alternative option is to pay per plant, for which buyers then get the exclusive right to harvest (F2).

The distribution of the Salicornia crisps to shops and hospitality industry on Terschelling is taken care of by a local wholesaler (F2). Some interviewees believe that there is also a market for processed goods on the mainland (E6, T), where the Salicornia crisps are already sold in different speciality shops and natural foods stores (F2). At present, the distribution of the crisps to these shops is arranged by one of the members of De Zilte Smaak (F2). Outsourcing this task to a specialised party could be a good option to increase sales volumes (F2).

5.1.4. Marketing and retail

As previously discussed, the market potential of saline products from Terschelling is considered positive (E6, F2, T, R1, R2). However, this market has yet to be developed (F2, T, R1). Positioning a product in the market requires time and expertise (F2, T). Currently, the demand for saline products is limited by lacking awareness amongst consumers with regard to the issue of salinization (E1, E3, E4, E6, T, R1, C1) and their unfamiliarity with halophytes (E1, E2, E3, E5, E6, T). Experts explain: ‘’for each product, the consumer’s knowledge is important; do people understand the product?’’ (E5) and: ‘’if consumers do not understand the importance of saline cultures, a label “salt tolerant” has no added value to them, and therefore neither to producers. At the moment, more is invested in, for example, organic products, as people are willing to pay more for those’’ (E4).

As a consequence, both marketing experts emphasize the importance of creating a differentiated product with additional attributes, such as locally produced (E5, E6) or the special saline taste (E6). Stakeholders recognize the importance of both attributes (R1, R2, C1 C2, C3). Especially the locality of the products is highly valued (F2, R1, R2, C1, C2, C3). The interviewees also consider important the healthy image of certain crops, such as Salicornia (R2) and quinoa (C2), and assumed health benefits of halophytes being a salt-substitute (F2). At this moment, most potential for the marketing and retail of saline products is seen in the regional niche market (E1, E4, E6). As the cost to produce food in salt affected soils is higher than fresh water grown crops it is crucial to identify, develop and market the added values such as special taste and locally grown (E4, F1).

The location on Terschelling offers a good opportunity to promote awareness on salinization and to familiarize people with saline crops (E1, E4, E5, R1). The island has an evident connection to the sea and visitors are increasingly aware of climate change, sea-level rise and increasing salinity of coastal agricultural lands (R1). In addition, saline vegetables support and strengthen the image of Terschelling with regard to nature, the outdoors and biodiversity (E5). Many tourists visiting the island enjoy trying something new. They form an accessible public for the message behind saline agriculture (E1, E4, E6, R1): ‘’I believe a regional approach, and specifically on an island, is very well-suited to promote awareness of salinization and to tell the story of saline agriculture’’ (E1). The cooperation with hospitality and tourism actors provides a good platform for this story to be told (E5, E6, F1, T, R1, C1): ‘’Saline agriculture might not yet mean much to people, but we are keen to tell the story behind it to our guests’’ (C1). One of the recreation entrepreneurs organises excursions to the field and tastings with saline vegetables on a regular basis (T). Interviewees also see possibilities in the different (sustainability-related) festivals that take place on Terschelling, such as Springtij (E5, R2), Oerol (E5, R2) and different fairs (R1).

5.1.5. Value chain alignment

The interview results combined with an analysis of the current value chain do reveal a number of possible divergencies between the options for future development. A first example is the balance between specialisation (scaling-up production volumes by focussing on a few crops), and differentiation (offering a wide variety of special species). Both famers see up-scaling as the way to make the field economically profitable (F1, F2). For the restaurants, however, production volumes are less relevant, as they mostly use the crops in applications with small volumes like garnish or as herbs (C1, C3). Producers of processed products, on the other hand, are more concerned about production volumes (R1, R2, T). Stakeholders seem unaware of this difference in perspective.

The selection of crops is a second potentially diverging issue. The species suitable for large scale production do not overlap with the species preferred by the prominent group of present buyers on the island (mainly restaurants). A final example of possible divergence among the present actors of De Zilte Smaak is the fixing of a price for the crops, especially as there is no real reference (F2, R2). Stakeholders hold different views on the value of the crops. One buyer took standard wholesaler prices as a reference for what they would be willing to pay (C1). For another buyer, the crops have added value because they are grown locally and can be freshly harvested (C3), while still another buyer is willing to pay less than traditional fresh water crops as it takes more time for the buyer to harvest and clean the crop. (R1). These results illustrate the early development phase of saline agriculture. Various future pathways are possible. The niche development on the island provides the opportunity to explore such pathways.

5.2. Trends relevant to the development of saline agriculture

The analysis of the value chain described above including the listing of issues and options illustrate the early phase of food production on salt affected soils. Applying the Multi-Level Perspective offer insights in the future of saline agriculture at three levels: the cultural landscape, the socio-technical regime and the niche innovation level.

5.2.1. Consumer trends, cultural landscape

Experts notice an increasing interest amongst consumers in healthy (E5) and organic (E6) food. Both trends are important in creating value for the products on Terschelling. The project, and similar initiatives, could therefore profit from these trends. The same is true for the increasing importance consumers attach to local food production (E2, E5, E6). There is more interest in shorter food chains and better traceable food as a result of the growing social debate on responsible food production (E5). Moreover, the movement calling for shorter food chains has gained momentum due to the COVID-19 crisis, which exposed the vulnerability of our current food system with extremely long supply chains (E5). The involvement of less intermediate parties can also help producers to receive a better price for their crops (E5). In summary the trends at socio-cultural level indicate a growing consumer interest in locally produced food and a growing societal interest in the environmental aspects of food. We conclude that the broader cultural trends are supporting the prospects for locally grown food on salt affected (degraded) land. This trend is likely to open up new funding possibilities for saline agriculture (E5).

5.2.2. Developments in agriculture

The traditional agricultural sector is well described in the Multi-Level Perspective (Geels, 2002). It is relatively stable due to the interdependencies between different regime actors. The regime is focussed on incremental innovation and its dynamic resists transformative change. However, the existing regime is under serious pressure, mainly for environmental reasons. New products are penetrating the old markets. For example, bio-organic farming and a shift from animal to plant proteins are gaining ground. Policies towards sustainability at the local and global level are putting more and more constraints on traditional farming, forcing the agriculture sector to explore new ways of producing food. Such developments support the need for innovation, including ways to improve soil health (E1, E3) and mixed and circular farming (E2, E5) and the goal to reduce the EU’s dependency on protein import (E3), as well as the movement which aims for a circular economy on the Dutch Wadden islands (E5). The opportunities for saline agriculture are likely to benefit from these developments. An example mentioned by the experts is the enrichment of soils with residual flows from saline systems (E2, E3). Another option is the application of organic fertilizers on saline soils (E3). Some interviewees stated that saline agriculture is argued to contribute to the enhancement of biodiversity (E1, E2). As one expert explains: ‘’Restoring a gradual fresh-salt gradient perpendicular to the coastline will result in restoring habitats lost in the past’’ (E2).

6. Discussion

This research explores the value chain for saline agricultural production on Terschelling and the prospects for its future development. The multi-level perspective framework of Geels (2002) has been used as a framework to describe and analyse the developments and trends in the agricultural sector in general and saline agriculture in particular. Looking from this perspective, saline agriculture on Terschelling is regarded as a niche likely to find its way in the dominant traditional agricultural regime.

Despite positive results on Terschelling, it is important to note constraints on the production side which include the lower yields than fresh water agriculture and the potentially negative effects of salt on the structure of clay soils. Another constraint is that saline agriculture can be labour-intensive. Further field experiments are likely to identify and remediate these constraints as well as lessons learnt from the organic agriculture becoming increasingly popular.

The expert interviews clearly revealed the chicken and egg question. A successful introduction of new food products requires a market ready to absorb the new product. At present there is not such a market for food grown of salt affected lands. There is a major gap between the reality of world-wide salinization and the awareness of this issue among farmers policy makers and consumers. Consequently, consumers are not willing to pay for the higher cost of producing food on salt affected soils.

Many of the stakeholders that were interviewed considered the locality aspects the most important unique selling point of saline grown food products. This is in line with previous findings in the literature, where the locality of agricultural products is shown to provide most added value and to be most beneficial in product differentiation (Hu et al., 2012; Loureiro & Hine, 2002; Mugera et al., 2017).

7. Conclusion

Our results show that the overall potential of the saline agriculture niche on Terschelling is considered positive, even though the commercial exploitation of saline agriculture is still a major challenge. There are different opportunities for the value chain in the processing stage such as development of new application domains for saline crops. The distribution chain requires further investigation. The marketing is also assessed as positive but requires more resources including time and expertise.

The focus on the touristic niche market enables the initiative on Terschelling to counter some important constraints identified in the interviews. It provides a better price for the crops to compensate for the lower and/or unstable yields and helps to promote consumer awareness, since tourists are more willing to try something new and are more receptive to the story behind saline agriculture. Additional attributes, such as their locality or special taste, are important in creating value for the crops. The location on the island, with its many tourists and evident connection with the sea, offers an important opportunity for the local development of saline agriculture. However, the help of volunteers in the project is still indispensable, as the production of the saline products is quite labour-intensive. Similarly the introduction of new products in a new market is very time-consuming as well.

The present situation and our analysis illustrate that volunteers and some public financial support will still be needed to gain experience in production, logistics and market development before the niche of saline agriculture at the tourist island of Terschelling can be run of a fully commercial basis. However, we believe that this can be achieved within a few years.

Islands are spaces with distinct social and environmental conditions that could favour the development of saline agriculture. Further comparative research is needed to fully understand the potential of islands as a niche for saline agriculture beyond the example of Terschelling. Moreover, the specificity of the island context means that generalising results to the mainland requires additional reflection and research. As climate change becomes more present with increasing droughts, freshwater scarcity and continued sea-level rise, the pressure to develop saline agriculture is likely to increase in the near future.

Disclosure statement

This research was supported by the Wadden Academy Leeuwarden, the Netherlands, and co-financed by the EU Interreg North Sea Region Programme.

Data availability statement

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to the privacy of research participants.

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.