Liquorice Cultivation Potential in Spain: A GIS-Based Multi-Criteria Assessment for Sustainable Rural Development

Abstract

In the framework of the European bioeconomy, liquorice (Glycyrrhiza glabra) represents a promising crop for sustainable agriculture due to its ecological adaptability, nitrogen-fixing capacity, and wide industrial applications. This study aims to identify suitable areas for liquorice cultivation across Spanish municipalities by integrating Geographic Information System (GIS)-based spatial analysis with a multi-criteria evaluation approach. Agronomic factors, annual mean temperature, soil pH, and water availability were combined with socioeconomic indicators including population decline, rural classification, and unemployment rate. Each municipality received a composite suitability score from 0 to 12 based on six criteria, with agronomic variables scored from 0 to 3 and socioeconomic factors assessed through binary classification. Results reveal that southern and southwestern regions, particularly Andalusia, Castilla-La Mancha, and Extremadura, exhibit the most favourable conditions for liquorice cultivation, offering both optimal environmental parameters and potential socioeconomic benefits. The study concludes that liquorice could serve as a regenerative and climate-resilient crop contributing to rural revitalization in Spain. A pilot case in Aragón illustrates its potential to promote social inclusion, repurpose historical assets, and stimulate local economies in depopulated, flood-prone areas.

1. Introduction

As the European Union intensifies its transition toward a circular and bioeconomy, supported by key frameworks such as the EU Bioeconomy Strategy and the European Green Deal [1,2], the identification of sustainable, versatile crops with ecological and socioeconomic value is gaining relevance. Among such crops, Glycyrrhiza glabra, a mediterranean perennial legume commonly known as liquorice, stands out for its ecological and commercial potential. Known for its deep root system, nitrogen-fixing abilities, and tolerance to semi-arid conditions, liquorice’ cultivation aligns with agroecological principles and offers promise for low-input agricultural systems, especially in Southern Europe.

Despite this potential, liquorice remains an underutilised crop in Spain, where its presence is mostly limited to wild harvesting, particularly in riparian and semi-arid zones. In countries like Italy, Turkey, and Iran, liquorice is already more systematically cultivated, further indicating untapped potential in the Iberian context. At the European level, entities and initiatives such as the REACH regulation on chemical safety, Horizon Europe funding programmes, and the EU Green Chemistry Strategy all support the development of bio-based, non-toxic molecules, a category that liquorice-derived compounds could potentially fall into.

Liquorice is popular for its sweet-tasting roots and its various applications in industry, food, and medicine [3]. Native to the Mediterranean region and some regions of Asia, it usually grows in warm and temperate climates and is highly adaptable to many soil types [3,4,5]. This crop grows vigorously in moist, nitrogen-rich soils, often found near riverbanks, streams, and irrigation ditches, sometimes persisting in the wild from previously abandoned cultivation sites [3]. Additionally, it demonstrates a notable tolerance to drought and saline soil, making it a resilient crop in regions where conventional agriculture may be limited [6,7].

Its vast root system, which allows it to access deep water reserves and improves soil, is one of liquorice’s most unique traits [4]. As part of the leguminous family, it engages in symbiotic nitrogen fixation, enriching the soil with essential nutrients and reducing the need for synthetic fertilisers [5]. These properties make liquorice a valuable crop for sustainable and regenerative agriculture. Accordingly, field maintenance is relatively low-intensity, involving periodic weeding, controlled irrigation, and pest management. Moreover, besides its roots, liquorice cultivation generates valuable byproducts [8,9]:

• Weeds: Can be composted or used as mulch.
• Leaves: Rich in nutrients and bioactive compounds; can be repurposed as soil amendments, used in animal feed, or valorised for cosmetic and medicinal applications.
• Stems: Often discarded, yet nutritionally dense and potentially rich in bioactive substances; can be processed for biomass energy, used as mulching material, or explored for fibre production.

Liquorice is notable for its high glycyrrhizin content, a compound with anti-inflammatory, antimicrobial, and antioxidant effects. Traditionally used to treat respiratory, digestive, and skin conditions, liquorice’s therapeutic use dates to ancient Egypt, Greece, and China. Current research explores its applications in antiviral treatments, gut health, and liver protection. Accordingly, its versatility is shown by the various uses in industry:

• Food and Confectionery [3,4,10]

  ○

  Flavouring agent: Used in sweets, candies, chewing gum, and beverages.

  ○

  Natural sweetener: Glycyrrhizin serves as a low-calorie sugar alternative.

  ○

  Herbal teas and alcoholic beverages: Commonly included in specialty drinks and herbal infusions.

• Pharmaceuticals and Herbal Medicine [3,4,10,11,12]

  ○

  Digestive health: Helps treat acid reflux, stomach ulcers, and gastrointestinal discomfort.

  ○

  Respiratory support: Found in syrups and lozenges for sore throats and cough relief.

  ○

  Anti-Inflammatory and immune boost: Used in chronic inflammatory conditions and immune support formulations.

  ○

  Adrenal and stress regulation: Helps manage cortisol levels and adrenal function.

• Cosmetics and Skincare [10,11,12]

  ○

  Skin brightening and anti-inflammatory: Commonly used in creams and serums to reduce hyperpigmentation.

  ○

  Anti-aging and antioxidant protection: Helps protect the skin from environmental damage.

• Agriculture and Environmental Uses [6,13]

  ○

  Natural pesticide: Acts as a mild insect repellent in organic farming.

  ○

  Soil remediation: Assists in reducing heavy metal concentrations in polluted soils.

• Traditional and Cultural Uses [3,5,10]

  ○

  Traditional medicine: Integral to chinese, ayurvedic, and middle eastern herbal treatments.

  ○

  Tobacco industry: Used to enhance the flavour and smoothness of tobacco products.

Due to its hardy nature, broad industrial uses, and capacity to improve soil quality, liquorice represents a sustainable and economically promising crop for bioeconomy further development. While its potential is well recognised in several countries, its status in Spain remains limited, being found both in the wild and under limited cultivation. It thrives in deep, nitrogen-rich soils and moist environments such as riverbanks and wetlands.

The distribution pattern of liquorice in Spain is depicted by a series of occurrence records that are grouped in some regions. Georeferenced data, including GBIF occurrence records and natural distribution surveys, indicate that the species has been recorded most frequently in Catalonia, the Ebro Valley, Castilla-La Mancha, Andalusia, and Extremadura [3,14]. The map presented below (Figure 1) indicates the recorded locations of liquorice across Spain, based on both historical data and recent observations.

Historically, Spain has relied on wild harvesting to meet the domestic demand for liquorice root. However, an overall increasing demand from the food, pharmaceutical, and cosmetic industries has been encouraging novel cultivation initiatives. In recent years, liquorice cultivation has extended beyond traditional local practices, as reflected in production statistics from 2015 to 2022 (Figure 2). The Ebro Valley has emerged as a strategic area for industrial-scale liquorice cultivation, particularly in Navarra and Aragón, due to favourable soil and climatic conditions. These regions dominate domestic production of liquorice sap and extract, thus offering an opportunity to reduce import dependency and promote sustainable, local agriculture. In 2023, Spain imported liquorice products worth approximately 802 k USD, while its exports reached only 133 k USD [15,16]. This trade imbalance underscores the potential for expanding domestic supply and reducing reliance on foreign sources.

The chart below reflects the evolution of liquorice industrial production in Spain from 2015 to 2022, showing an overall increase and diversification of production zones. It can be observed that Navarra consistently leads in total production, while Aragón and Madrid regions show fluctuating contributions, particularly strong from 2019 to 2022.

To complement this broader perspective, a closer look at the provincial distribution of liquorice cultivation in Spain (ref. year 2022) is shown in

Table 1. Area and industrial production of liquorice in Spain (2022) [17].

Province	Rainfed Surface (ha)	Irrigated Surface (ha)	Total Surface (ha)	Performance Rainfed/Irrigated (kg/ha)	Production (tons)
Navarra	—	108	108	-/2045	221
Aragón	16	19	35	719/2500	59
Madrid	—	21	21	-/2975	62

:

The data above highlights that the liquorice cultivation in Spain is still limited and, although fluctuating, there is a growing overall tendency particularly in the regions of Navarra, Aragón, and Madrid. Notably, liquorice is primarily cultivated under irrigated conditions, which significantly enhances yield compared to rainfed production. These figures point to a potential of achieving an intensified, high-efficiency cultivation, especially in regions where water resources and agronomic conditions allow for a stable output.

As for the global market for liquorice extract, a steady growth can be observed, driven by increasing demand from the food, pharmaceutical, and cosmetics sectors. Accordingly, recent trade data from the OEC platform highlights a strong export value of USD 161 M for liquorice extract in 2023 [18] with France (USD 28.6 M), Uzbekistan (USD 26.8 M), and China (USD 25.3 M) leading in 2023 [16]. Market research projects a continued growth at a CAGR of at least 4.5%, driven by the following factors [19,20,21]:

• Increased consumer preference for natural ingredients—As consumption trends shift towards organic and naturally derived products, liquorice extract is gaining popularity in various formulations.
• Expanding applications—Beyond traditional medicinal uses, liquorice extract is increasingly used in functional foods, dietary supplements, and natural cosmetics.

These reports highlight innovations in extraction and processing techniques, along with enhanced regulatory frameworks that are helping to drive market expansion. At the commercial level, prices vary significantly depending on processing and certification: raw root sells for around 1.50 €/kg, while organic extracts range between 30 and 40 €/kg, and final consumer products may easily exceed 100 €/kg, particularly in the cosmetics and fine chemistry sectors. These figures show that liquorice is not only agronomically promising, but also economically viable, especially if integrated into local, decentralised supply chains and supported by eco-certification [22,23].

At the national level, Spain presents a unique case within this global framework. Despite its track record of wild harvesting, the country’s domestic liquorice extract supply remains limited, often meeting demands through imports [18,24]. At the European level, a similar pattern exists. For instance, trade stats highlight a consistent gap between imports and exports. In 2023, for instance, the EU imported about 65.1 million USD in liquorice extract, while exports only reached roughly 55.6 million USD. Even with rising demand, Europe remains reliant on imports from non-EU countries. This ongoing trend points to a clear strategic opportunity: expanding internal cultivation and processing. Given its favourable agro-climatic conditions and the need for new sustainable and local initiatives, Spain could play a pivotal role in strengthening Europe’s bioeconomy and autonomy (see Figure 3) [18,24].

Beyond its environmental resilience and economic versatility, liquorice also offers significant social value, particularly in regions affected by depopulation and structural decline. As a sustainable, low-input crop, liquorice can contribute to territorial cohesion by creating employment opportunities, promoting agricultural diversification, and supporting inclusive business models that engage women with familiar charges, youth, caregivers, among others. Experiences from social farming and cooperatives demonstrate how plant-based value chains can revitalise rural areas facing demographic stress [25,26,27]. Moreover, the crop’s long harvest cycle and capacity for value-added transformation make it especially suitable for circular rural entrepreneurship, including the production of eco-certified cosmetics, functional foods, and high-value extracts.

Although several studies have modelled the ecological or habitat suitability of Glycyrrhiza glabra, mostly in China, Iran and Central Asia, these works focus exclusively on biophysical predictors such as climate, soil properties, or salinity. Other lines of research examine agronomic performance in saline or degraded environments, or they explore the crop’s economic relevance through local case studies, but none develop a spatially explicit, multi-criteria framework. To date, no study has integrated GIS-based agro-environmental suitability with quantitative indicators of socioeconomic vulnerability specifically for G. glabra, nor has such an approach been applied within the Mediterranean region or at national scale in Spain [28,29,30,31]. The absence of such cross-sectoral, spatially resolved analyses constitutes a significant gap in the existing literature. This gap limits the capacity to identify priority areas where liquorice cultivation could contribute simultaneously to sustainable agriculture and rural development. The present study addresses this by integrating climatic, edaphic, hydrological, and territorial variables into a GIS-based, municipality-level suitability model for Spain.

Accordingly, this study pursues three main objectives:

• To identify the agro-environmental factors that determine the suitability of Glycyrrhiza glabra cultivation in Spain;
• To develop a GIS-based multi-criteria assessment that integrates climatic, edaphic, hydrological, and socioeconomic variables at municipal scale; and
• To classify and map priority areas for potential liquorice expansion, highlighting zones where cultivation may contribute simultaneously to sustainable agriculture and rural development.

This study contributes to the academic literature by integrating agronomic GIS-based modelling with socioeconomic vulnerability indicators within a unified multi-criteria framework. As such, this work brings both dimensions together at municipal scale. Furthermore, it proposes a replicable analytical framework that can be applied to other crops, supporting the design of bioeconomy-oriented land-use strategies and strengthening the role of spatial modelling in sustainable rural development.

Given the dual ecological and socioeconomic relevance of sustainable liquorice cultivation, this study explores its current and potential role in the context of Spain. Accordingly, it integrates agronomic analysis with territorial and social criteria to identify high-priority zones for expansion and outlines a roadmap for liquorice-based value chains, aligned with both environmental resilience and rural development objectives. The article also proposes a methodological approach that could be replicated in other Mediterranean contexts.

2. Methodology

The methodological approach adopted in this study combines a spatial analysis with a multi-criteria evaluation to assess the potential for expanding liquorice cultivation across Spain. The aim was to identify areas that are not only agro-climatically suitable for liquorice, but also socioeconomically promising in terms of their potential to benefit from new agricultural developments. The approach was structured into three stages: (1) data collection and layer preparation, (2) suitability scoring and spatial overlay, and (3) classification and prioritisation.

2.1. Data Collection and Layer Preparation

The first phase involved the identification and collection of data from relevant sources. Agronomic variables such as average annual temperature, annual precipitation, soil pH, and flood-prone zones were gathered from national and European public databases [32,33,34]. Many of these datasets were accessed through Web Map Services (WMS), primarily from the Spanish Ministry of Agriculture, Fisheries and Food and from the Joint Research Centre’s European Soil Data Centre (ESDAC). These WMS layers served as visual guides for the manual creation of vector shapefiles in QGIS (version 3.34.5, QGIS Development Team, Grüt, Switzerland).

Shapefiles were constructed directly by digitising polygon boundaries over WMS references. These layers were used to extract agronomic values at the municipal level. For soil pH, the dominant pH class within each municipality was recorded. These values were derived from the ‘Soil pH in Europe’ dataset provided by the European Soil Data Centre (ESDAC–JRC), originally distributed as a 1 km raster grid created through regression–kriging using 12,333 measured soil samples across Europe. This spatial resolution is appropriate for capturing broad pH gradients at the municipal scale, while acknowledging that fine-scale intra-municipal heterogeneity may not be fully represented [34]. Continuous variables such as mean annual temperature and total annual precipitation were extracted using zonal statistics. All vector layers were projected to a consistent coordinate reference system (ETRS89/UTM Zone 30N). Topological integrity was verified to detect and correct issues such as slivers, gaps, or overlaps between polygons. Additionally, a consistency check was conducted to ensure coverage and completeness across the national territory.

In parallel, socioeconomic variables relevant to rural development, namely population trends, unemployment rates, and rural classification, were collected from official statistical sources and integrated into the same GIS framework. Municipalities were categorised as follows: “Small rural” if the population was under 5000; “Rural” between 5000 and 49,999; and “urban of high density” if over 50,000 inhabitants, in accordance with national classification standards [35,36]. This classification essentially bridges two differing frameworks: on one side, there is Spain’s Law 45/2007, which labels municipalities with fewer than 30,000 residents as rural, and on the other, the EU’s degree of urbanisation (DEGURBA) typology. The latter sets 5000 inhabitants as the threshold for urban status and regards areas with over 50,000 people as high-density urban centres. So, by grounding itself in population numbers, this system manages to satisfy Spain’s statutory rural definition while also acknowledging the EU’s emphasis on varying levels of urban density. Ultimately, it weaves together legal and analytical perspectives into a single, coherent structure [35].

2.2. Suitability Analysis Through Spatial Overlay

To provide a transparent and scalable evaluation framework, a scoring system was designed to quantify the suitability of each municipality based on a total of six criteria: three agronomic and three socioeconomic. Each agronomic criterion could score between 0 and 3 points, while each socioeconomic indicator contributed 1 point if the condition was met. This results in a composite suitability score ranging from 0 to 12 points per municipality.

The agronomic criteria included mean annual temperature, soil pH, and water availability (i.e., a combined index based on annual precipitation and proximity to flood-prone zones). Furthermore, the following socioeconomic criteria, available in national official databases (INE, Spanish Statistical Office), were considered:

• Depopulation trend: municipalities showing a sustained negative demographic balance during most of the 2014–2024 period, according to official INE records [36].
• Rural classification: municipalities classified as rural or semi-rural (i.e., under 50,000 inhabitants).
• Unemployment rate: municipalities with an unemployment rate above the national average.
• Socioeconomic indicators were operationalised as binary variables by design. This approach ensured harmonisation across heterogeneous data sources and, importantly, prevented the socioeconomic dimension from outweighing the agronomic criteria within the composite model. The binary structure reflects an intentional weighting strategy rather than a strict representation of underlying socio-economic gradients, as for the value chain development crop suitability in terms of agronomic criteria (with no need of major interventions) was considered a priority.

For the agronomic criteria, each variable was assigned to a score according to threshold ranges derived from scientific literature and expert consultation specific to liquorice cultivation [3,37,38,39,40]. As mentioned above, the water availability index was calculated by combining annual precipitation values and proximity to mapped flood-prone zones. Municipalities were considered “near flood zones” if a significant portion (>20%) of their surface overlapped with designated flood risk areas. This combined approach reflects both water supply potential and soil moisture retention capacity, which are relevant for liquorice cultivation. The scoring criteria are summarised in

Table 2. Scoring criteria, ranges, and scores.

Criterion	Range/Class	Score	Source
Mean annual temperature	20–25 °C	3	[37,38,39,40]
	17–19.9 °C or 25.1–27 °C	2
	14–16.9 °C or 27.1–29 °C	1
	<14 °C or >29 °C	0
Water Availability (precipitation + floodplain proximity)	500–1000 mm/year and near flood-prone zone	3	[41,42]
	500–1000 mm/year or near flood-prone zone	2
	400–499 mm/year, no floodplain	1
	<400 mm or arid	0
Soil pH	6.5–7.5 (optimal)	3	[41,42,43,44,45]
	6.0–6.49 or 7.51–8.0	2
	5.5–5.99 or 8.01–8.5	1
	<5.5 or >8.5	0
Depopulation trend	Sustained population decline (2014–2024)	1	[36]
Rural classification	Municipality with less than 30,000 inhabitants	1	[35]
Unemployment	Rate above national average	1	[46]

.

Once individual scores were assigned for all criteria, a composite suitability score was calculated for each municipality by summing the six values. This process was implemented through spatial overlay operations in QGIS, using field calculations and zonal statistics on harmonised layers.

2.3. Spatial Classification and Prioritisation

To interpret the composite scores and guide future planning, municipalities were classified into four suitability categories:

• High suitability: 10–12 points.
• Moderate suitability: 7–9 points.
• Marginal suitability: 5–6 points.
• Low suitability: <5 points.

These categories reflect a balanced integration of environmental and socioeconomic dimensions. Municipalities scoring in the highest tier not only meet optimal agronomic conditions for liquorice cultivation but also represent areas where economic revitalization through sustainable crops could have a meaningful social impact.

This framework enables the identification of territories where liquorice cultivation is technically feasible, socially relevant, and potentially impactful in the context of territorial policy and rural regeneration strategies. Importantly, the methodology presented in this study is replicable for other crops and adaptable to other regions seeking to combine environmental resilience with rural development.

3. Results and Discussion

This section explores the feasibility and advantages of expanding liquorice cultivation in Spain by analysing in depth the plant’s agronomic requirements, its economic profitability, its role in social and territorial development, and the identification of optimal cultivation zones based on the layers developed in GIS.

3.1. Overview of Agronomic Requirements

Agronomic suitability was assessed through three variables, mean annual temperature, soil pH, and water availability, each scored from 0 to 3, as detailed in the in Section 2 (Methodology). This section interprets the spatial patterns observed in each individual variable, based on their respective distribution maps (Figure 4a–d).

Figure 4a illustrates the average annual temperature across Spain. The most favourable areas, corresponding to values above 20 °C, are concentrated in the south of the Iberian Peninsula, particularly in Andalusia, Murcia, Extremadura, and parts of Castilla-La Mancha and Valencia. These regions fall within or near the optimal thermal band for liquorice. In contrast, northern and inland mountainous zones remain well below this threshold, limiting agronomic potential due to suboptimal root development conditions.

Figure 4b shows the distribution of mean annual precipitation. While large parts of the country receive between 400 and 800 mm per year (which is marginal to acceptable for liquorice cultivation) the most favourable ranges of 500–1000 mm occur irregularly and are more common in river basins, especially in the Ebro, Guadalquivir, and Tagus valleys. Areas with values below 400 mm (particularly in the southeast and some countryside zones) may require supplemental irrigation to support cultivation under stable conditions.

Figure 4c adds further nuance by incorporating flood-prone zones and permanent water bodies. When combined with precipitation data, this panel helps identifying municipalities with sustained or seasonal water availability, an asset for liquorice, which benefits from occasional soil saturation without long-term waterlogging.

Figure 4d represents the distribution of soil pH at a municipal level. The most suitable pH range (6.5–7.5) is predominant in eastern and southern Spain, especially in areas with calcareous substrates. Conversely, acidic soils (pH < 6.0) dominate in Galicia, Asturias, and northern Castile and León, which significantly reduces suitability, unless soil correction measures are implemented.

The spatial distribution of these variables reveals consistent patterns. Municipalities in southern and eastern Spain, along with those in major river valley corridors such as the Ebro and Guadalquivir, frequently meet two or more optimal agronomic thresholds. While some areas meet only one criterion, the convergence of moderate-to-warm temperatures, sufficient water availability, and neutral to slightly alkaline soils is particularly frequent in the southern and southeastern regions of Spain, making them promising locations for cultivation.

Although Glycyrrhiza glabra is often described as a temperate–continental species, major taxonomic sources identify its native distribution as spanning large parts of the Mediterranean and Central Asian regions [47,48]. In the case of Spain, some global catalogues list the species as introduced, yet national inventories and regional floristic databases consistently classify it as an autochthonous or long-established element of the Iberian flora, particularly in southern and central regions [3,48]. Herbarium and occurrence records further corroborate its presence in multiple Spanish provinces, including municipalities situated along major river systems such as the Ebro, Guadalquivir, and Guadiana [14].

Ecologically, G. glabra typically inhabits alluvial and riparian environments characterised by deep, loose, periodically moist soils, a habitat profile fully compatible with Mediterranean river valleys [49]. Historical accounts and field-based observations describe the species as thriving in semi-arid settings where intermittent moisture, shallow groundwater and fertile alluvial substrates support its development [3,47]. Its deep rhizomatous system confers substantial tolerance to high summer temperatures and prolonged drought, while its moderate salt tolerance and preference for calcareous or mildly alkaline soils align with edaphic conditions widely present in southern Spain [47,50].

Consequently, expanding liquorice cultivation in Spain involves managing a native or long-established species rather than introducing an alien taxon, despite the “introduced” designation used in some global datasets [47]. The identification of high-potential areas in southern and eastern Spain is therefore coherent with both its documented presence and its known ecological plasticity [3,14,48].

It is important to note that commercial liquorice generally requires periodic irrigation during its establishment phase and under prolonged summer drought. However, the suitability patterns identified in this study prioritise municipalities with natural water support, such as river-valley corridors, alluvial soils or shallow groundwater, conditions that substantially reduce the need for supplemental irrigation [3,49]. Therefore, the findings do not imply promoting cultivation in severely water-stressed areas, but rather in locations where liquorice can be grown efficiently and in accordance with water-saving objectives consistent with the EU Bioeconomy Strategy.

3.2. Socioeconomic and Territorial Development Opportunities

In addition to agro-environmental suitability, the feasibility study of introducing liquorice as a strategic crop must take into account the socioeconomic dynamics of rural Spain. The integration of territorial vulnerability indicators into the model enables highlighting areas where liquorice cultivation could contribute not only to agricultural diversification, but also to broader goals of rural revitalization, job creation, and territorial rebalancing.

Figure 5a shows the typology of Spanish municipalities based on demographic structure. According to the classification defined in Law 45/2007, municipalities with fewer than 30,000 inhabitants are considered rural. Within this group, small rural municipalities (under 5000 residents) are the most common. These areas are predominantly located in the interior and northwest/northeast of the country, particularly in Castilla y León, Extremadura, Aragón, and parts of Galicia, and represent the structural core of Spain’s sparsely populated territories.

Figure 5b illustrates population variations between 2014 and 2024. A vast number of municipalities, especially across the interior plateau, northwestern regions, and parts of Andalusia, are experiencing a sustained population decline [30,42]. This trend results from a combination of structural factors (economic, demographic, social, and geographic) that have shaped rural Spain over recent decades. Economically, the scarcity of job opportunities, lower wages, and limited diversification have pushed younger populations toward urban centres. Socially and culturally, rural areas suffer from reduced access to healthcare, education, and mobility, reinforcing the perception of urban life as more attractive. Demographically, low birth rates, ageing populations, and the outmigration of young adults, especially women, lead to a lack of generational renewal. Geographically, isolation and weak infrastructure further hinder demographic resilience [51,52,53,54,55,56,57].

The consequences are significant: ageing populations increase service needs while undermining the social and economic sustainability of rural areas; entire villages face abandonment, risking the loss of cultural heritage; and public services are progressively withdrawn. Economically, rural areas face declining productivity and greater external dependency. Environmentally, land abandonment leads to biodiversity loss, erosion, and wildfire risk. These combined effects deepen territorial inequality between shrinking rural zones and expanding urban areas, a phenomenon widely referred to as “la España vaciada” (“emptied Spain”). Tackling this requires integrated agro-territorial strategies that combine agricultural innovation with demographic and infrastructural revitalization [51,52,53,54,55].

Figure 5c depicts unemployment rates by municipality. The highest levels of unemployment (>15%) are concentrated in the southern part of the country, particularly in Andalusia, Extremadura, and areas within Castilla-La Mancha. These same regions overlap with many of the high-suitability agronomic zones identified earlier, reinforcing the potential of liquorice as a crop with combined agricultural and social impact.

Taken together, the spatial distribution of these variables suggests that a considerable number of municipalities face overlapping structural constraints. This reinforces the relevance of identifying productive strategies that not only fit the agro-environmental context but also support rural employment, land activation, and territorial equity. These findings set the stage for the combined suitability analysis presented in the next section.

3.3. Composite Suitability Score

The spatial application of the suitability model produced two key outputs. First, an agronomic suitability score, based solely on temperature, water availability, and soil pH; and second, a composite score that incorporates both agronomic and socioeconomic variables into a single index ranging from 0 to 12.

The results of the combined agronomic assessment are shown in Figure 6, where municipalities are classified according to their cumulative score (maximum 9 points). The highest suitability values (scores 7–9) appear predominantly in the country’s south region, with notable clusters in Andalusia, southern Castilla-La Mancha, Extremadura, and parts of the Valencian Community. These territories consistently meet at least two of the three optimal conditions for liquorice cultivation. Medium-range scores (4–6) dominate much of central and eastern Spain, typically reflecting mixed conditions, such as appropriate pH but insufficient rainfall, or favourable temperatures with suboptimal soils. In contrast, the lowest scores (1–3) are concentrated in northern and northwestern regions, including Galicia, Asturias, and parts of Castilla y León, where colder climates and acidic soils impose significant constraints.

Building on this layer, Figure 7 presents the composite suitability map, which also integrates the three selected socioeconomic indicators. This extended analysis modifies the distribution of high-suitability zones by incorporating territorial vulnerability into the scoring. As a result, additional municipalities, especially in eastern Andalusia, Extremadura, and sections of the middle Ebro corridor, reach the highest category (scores higher than 10). Accordingly, these areas combine agronomic feasibility with structural vulnerability, suggesting a double benefit: productive potential and social return.

The comparison between both assessments reveals meaningful shifts. While the southern and southeastern regions consistently dominate the upper range, the inclusion of socioeconomic data helps to refine priorities and broaden the concept of suitability beyond purely environmental thresholds. Altogether, the composite scoring framework enables the identification of the following:

• High-priority zones (scores 10–12), where liquorice cultivation could simultaneously improve land-use efficiency and contribute to rural development goals.
• Moderate-suitability areas (scores 7–9), where either the agronomic or social dimension is partially met.
• Low-suitability municipalities (≤6), which may require substantial adaptation or be excluded from short-term planning.

These spatial patterns are also consistent with the agronomic and ecological requirements of Glycyrrhiza glabra described in previous research. The species shows a marked preference for warm, semi-arid environments and for deep, well-drained soils with neutral-to-moderate alkaline pH, conditions that optimise root growth and biomass accumulation [58,59]. Its documented adaptability to alkaline and weakly saline soils, where it can reduce soil pH, exchangeable sodium and overall salinity, aligns with the presence of suitable areas identified in Mediterranean river basins and semi-arid regions of Spain, which resemble the environments where liquorice cultivation has been successfully implemented in Central Asia [59,60,61]. Likewise, the concentration of high composite scores along major river corridors mirrors long-standing observations of wild and cultivated stands of G. glabra in Mediterranean alluvial and riparian landscapes, such as riverbanks, dry streambeds, and floodplain terraces [3,5,11,49].

Importantly, most GIS-based or ecological assessments of liquorice focus exclusively on biophysical parameters, such as climate, soil properties, or topography, without integrating socioeconomic indicators [28,29,62,63]. By incorporating demographic decline, rural classification and unemployment into the analysis, the present framework introduces a territorial dimension rarely addressed in liquorice-related studies, enabling the identification of areas where cultivation may contribute to agricultural diversification, employment creation, and rural revitalisation. This multidimensional approach enhances the interpretative depth of the model and reinforces the relevance of liquorice as a crop with both agronomic and socio-territorial potential, particularly in marginal or semi-arid regions where previous case studies already highlight its capacity to improve soil productivity and rural incomes [60,61].

3.4. Case Study: The EcoRadiz Project

The results presented in the previous sections highlight regions across Spain where liquorice cultivation is both agronomically viable and territorially strategic. To illustrate how these suitability criteria can be materialised, this section presents a real example of implementation: the EcoRadiz project, located in the municipality of Pina de Ebro (Aragón).

EcoRadiz serves as a proof of concept of how liquorice can be integrated into local economies through a circular and socially inclusive model. The project addresses many of the structural challenges identified, such as land underuse, demographic decline, and limited employment opportunities, while capitalising on favourable environmental conditions identified in the spatial analysis and the historical cultivation of liquorice in the region.

Located along the middle Ebro corridor, Pina de Ebro falls within one of the moderate-to-high suitability clusters identified in the composite map (Section 3.3). It combines near-optimal thresholds for temperature, soil pH and water availability with all three socioeconomic criteria used in the model: population decline, rural classification and unemployment above the national average. This makes Pina de Ebro a representative example of the type of municipality prioritised by the suitability framework and an appropriate testing ground for developing a liquorice-based value chain.

From an environmental perspective, the municipality is characterised by proximity to flood-prone areas and calcareous soils, which provide both adequate water availability and compatible pH conditions for liquorice. The local climate, with warm summers and low frost risk, further reinforces its agronomic suitability. Figure 8 shows a zoomed-in view of the Aragón region, highlighting the municipality of Pina de Ebro.

The EcoRadiz project demonstrates the integration of liquorice cultivation into a circular, socially inclusive value chain (Figure 9). From the recovery and processing of raw roots (left) to the development of ecological products and outreach activities (right), EcoRadiz illustrates how traditional crops can be transformed into drivers of rural innovation and community resilience.

EcoRadiz is structured around a circular, socially inclusive model. It reclaims municipal land and infrastructure, notably an old laundry house, now being renovated into a processing workshop for organic liquorice products. The project’s objectives include the following:

• Resuming the cultivation of a traditional crop with deep cultural roots in the region.
• Generating employment opportunities for socially vulnerable women, with a flexible, self-managed working model.
• Promoting organic farming and sustainable resource use, including solar energy and local wool-based insulation.

The cooperative has already launched a first round of activities, including the following:

• Cultivation trials on 1 hectare of municipal land, using 400 kg of initial planting material.
• Acquisition of 4000 kg of organic liquorice root from other Spanish producers for early-stage processing tests.
• Interior refurbishment of the workshop using sustainable materials and installation of 8 (from a capacity of 12) solar panels.
• Training of 14 women in agro-processing tasks, with four of them expected to lead the daily operations.

The workshop will also include an area designed to encourage outreach and educational activities, visitor interactions and direct sales of liquorice’ local products. Washing steps of the process will be carried out through traditional irrigation channels without using synthetic products, thus minimising environmental impacts while strengthening the connection to local knowledge systems.

EcoRadiz envisions a fully integrated value chain, with activities extending beyond primary processing. The project plans to commercialise a range of ecological liquorice products (sticks, powder, slices, and extracts) through direct sales (on-site and online) and B2B agreements with local actors in the food and cosmetic sectors. Furthermore, an important aspect of the value chain proposed includes the reuse of liquorice by-products (leaves, stems, weeds) for compost, mulch, livestock feed, or bioenergy, reinforcing a circular production model.

With an expected processing capacity of 4000–4500 kg per year at the current workshop (assuming a team of 4 people processing 25 kg of liquorice daily), the cooperative anticipates achieving economic sustainability within two to three years, depending on yields and market demands. Currently, a portfolio of 15 products derived from liquorice is available commercially and can be acquired (in person or online) with prices ranging from 20 to 140 EUR/kg.

This case illustrates how a rural municipality with adequate cultivation conditions, when supported by strong local agency and institutional collaboration, can transform its potential into a concrete initiative with social, economic, and environmental impacts. EcoRadiz demonstrates that a relevant value chain can be recovered through adaptive planning and that liquorice can serve not only as a crop, but as a vehicle for inclusive rural innovation. Its model is both locally grounded and replicable, offering inspiration for similar territories within the suitability categories defined in this study.

3.5. Synthesis, Strategic Reflections and Limitations

The results of this study reveal a promising potential for liquorice cultivation in Spain. One of the most significant findings is the clear spatial overlap between high agronomic suitability and socioeconomic vulnerability in southern and inland Spain. Regions such as Andalusia, Extremadura, and Castilla-La Mancha consistently score highly in both dimensions. This convergence suggests that liquorice could serve not only as a new crop for Mediterranean agriculture, but also as a lever for economic diversification, land rehabilitation, and rural jobs creation.

From an agronomic perspective, our findings are coherent with existing plot-scale and regional studies on Glycyrrhiza glabra, which consistently document its strong tolerance to water stress, its favourable response to neutral–alkaline and calcareous soils, and its suitability for semi-arid and Mediterranean-type climates [28,59,60,63,65,66]. These studies also highlight its capacity to improve soil conditions in marginal, weakly saline, or sodic environments, reinforcing the relevance of the suitability patterns identified in this work [28,59,60,63]. However, most of these contributions remain confined to controlled field trials, pot experiments, or geographically limited case studies in regions such as Iran, Turkey, Uzbekistan, or Kazakhstan, without extending to national-scale spatial assessments [10,28,29,63]. While GIS- and model-based suitability approaches have been widely applied to other Mediterranean crops, including olives, almonds, and grapevines, to support land-use planning and climate adaptation strategies, liquorice has largely been absent from such multi-criteria evaluations. By applying a spatially explicit, multi-criteria suitability analysis to this underutilised crop, the present study addresses this methodological gap and positions liquorice alongside other climate-resilient Mediterranean perennials within contemporary land-use and bioeconomy planning frameworks [62,67,68,69,70,71].

These results reinforce the value of territorialized agricultural planning: rather than applying one-size-fits-all solutions, it is more effective to match crops to the specific agroecosystems and define priorities align with key characteristics of each territory. In this respect, liquorice aligns well with multiple policy agendas, including the fight against desertification, the promotion of regenerative agriculture, and the demographic revitalization of sparsely populated areas.

The integration of socioeconomic indicators into the suitability framework is aligned with recent GIS-based studies that combine biophysical and territorial variables to prioritise interventions in rural areas, where spatial multi-criteria approaches increasingly incorporate demographic decline, ageing and economic vulnerability into land-use decision-making [72,73,74]. In the Spanish context, our results connect directly with the debate on la España vaciada, as many of the municipalities identified as highly suitable for liquorice cultivation overlap with areas affected by persistent depopulation, strong demographic ageing and structural unemployment patterns well documented at the municipal scale across interior provinces [75,76,77]. Whereas previous research on rural depopulation has centred on diagnosis, characterisation of socio-demographic trends and policy narratives, the present work introduces a concrete crop-based perspective that could be operationalised through targeted pilot programmes and value-chain investments. In this sense, liquorice functions not only as a niche perennial legume but also as a test case for how bio-based crops can support territorial cohesion, echoing ongoing European bioeconomy efforts that link biomass supply chains, rural regeneration strategies, and regional development objectives [78,79,80].

In methodological terms, the GIS-based scoring framework used in this study constitutes a replicable and scalable tool. The model can be adapted to other (underutilised) crops or replicated in other countries seeking to integrate agronomic feasibility with territorial policy goals. Its modular structure allows for updates as new environmental datasets, climate projections, or socioeconomic indicators become available. Nonetheless, some limitations must be acknowledged:

• The model is based on static climatic averages and does not account for interannual variability or future climate scenarios.
• Soil data is restricted to pH, without factoring in salinity, organic matter, or texture factors that may influence crop performance.
• The socioeconomic dimension includes only three indicators; other factors such as age structure, land tenure, or value chain maturity were not incorporated due to data limitations.
• The scoring thresholds, while grounded in the literature, still involve subjective categorization and can benefit from expert calibration or stakeholder validation processes.
• Although native or long-established in Spain, G. glabra can expand vigorously in riparian areas. The model omits ecological-risk indicators, which should be integrated in future assessments.
• The current scoring system relies on broad threshold categories for socioeconomic indicators; more granular classes could enhance the robustness of the assessment and bring the framework closer to formal MCDA standards.

These limitations should be understood in relation to established methodological standards in multi-criteria evaluation and spatial decision-support tools. Unlike formal MCDA frameworks such as AHP, TOPSIS or weighted linear combination, commonly used in GIS-based suitability studies, our scoring system relies on fixed threshold categories rather than expert-derived weighting or pairwise comparisons. Similarly, the use of static climatic averages departs from best practices in climate–soil suitability modelling, where trend-based or scenario-driven datasets are typically recommended. Finally, the reliance on municipal-scale socioeconomic indicators, while consistent with spatial planning approaches, reflects a simplified operationalisation compared to more comprehensive SDSS frameworks that integrate accessibility, land-use constraints, or value-chain maturity. In this context, adopting more granular scoring schemes for socioeconomic indicators (e.g., distinguishing between moderate and very high unemployment levels) would further align the framework with MCDA standards and enhance its interpretative depth. Recognising these divergences clarifies the scope of the model and highlights opportunities for future refinement.

Beyond these limitations, the GIS-based framework developed here has strong potential for replication in other Mediterranean regions and for application to additional underutilised crops. Its structure, built on harmonised climatic, hydrological, edaphic, and socioeconomic layers, can be generalised provided that comparable spatial datasets exist and that scoring thresholds are recalibrated to crop-specific requirements. The approach is particularly suited to regions with marked agroclimatic gradients, consistent municipal-level statistics, and policy interest in bioeconomy-oriented diversification. Under these conditions, the framework can serve as a scalable decision-support tool to identify suitability patterns, prioritise pilot areas and support strategic planning for emerging crops.

Overall, the study contributes to three strands of literature: (i) agronomic and ecological research on liquorice, by translating crop requirements into a spatially explicit national suitability model; (ii) GIS-based multi-criteria assessments for Mediterranean agriculture, by incorporating liquorice into the portfolio of crops considered for climate-resilient land-use planning; (iii) rural development studies, by empirically demonstrating the spatial overlap between agro-environmental potential and territorial vulnerability in southern Spain. This cross-fertilisation between agronomy, spatial modelling and rural development strengthens the academic contribution of the study and positions it as a methodological reference for future research on underutilised crops and integrated land-suitability assessments.

In addition, the study advances current debates in bioeconomy research by demonstrating how crop diversification strategies can be grounded in spatially explicit, evidence-based assessments. The results illustrate that underutilised perennial crops such as liquorice can support circular value chains by enabling local processing, by-product reutilisation, and low-input cultivation systems. Moreover, the spatial overlap between high suitability and structurally vulnerable rural areas highlights how crop diversification, when strategically planned, can contribute to socio-economic regeneration. In this sense, the proposed framework offers a concrete pathway for linking bio-based production models with territorial cohesion objectives, thereby enriching the conceptual and empirical foundations of bioeconomy-oriented rural development.

4. Conclusions and Recommendations

Overall, this study demonstrates the significant potential of liquorice as a strategic crop for promoting sustainable agriculture and rural revitalization in Spain. By integrating agro-environmental and socioeconomic data in a GIS-based suitability model, it identifies territories where liquorice cultivation is not only technically viable but also aligned with pressing demographic and territorial challenges. Key findings include the following:

• Optimal growing conditions correspond to areas with mean annual temperatures above 16 °C, neutral to slightly alkaline soils (pH 6.5–7.5), and annual precipitation between 500 and 1000 mm.
• Southern and southwestern regions, particularly Andalusia, Extremadura, and Castilla-La Mancha, are identified as high-potential regions in terms of combined environmental and social suitability.
• Moderate-potential zones exist across eastern and interior Spain, where targeted interventions could unlock productive capacity.
• Northern regions present structural limitations for cultivation but may serve niche purposes under specific conditions or as part of experimental pilot schemes.

Based on these results, several recommendations can be drawn: for instance, the implementation of pilot schemes in priority areas can validate the suitability of liquorice cultivation under local conditions, as well as the expected social benefits. To encourage farmers to adopt this crop, incentives, and subsidies within rural development policies, such as CAP eco-schemes and NextGen funds are fundamental. In parallel, public–private partnerships can play a key role in establishing the required infrastructure as well as improving market access through synergies. And finally, through research efforts, liquorice’s potential in soil regeneration, carbon sequestration, circular value chains, and the development of novel biobased products can be strengthened.

From a managerial perspective, the results provide actionable guidance for farmers, cooperatives, and local administrations. In high-suitability municipalities, liquorice can be introduced as a complementary perennial crop requiring limited inputs and offering opportunities for local processing, particularly suited for smallholders and social cooperatives. Farmer organisations and producer groups may use the suitability maps to prioritise pilot plots, optimise irrigation planning, and evaluate the feasibility of small-scale value-added transformation. For local administrations, the identification of priority areas supports land-use planning, the activation of underutilised public land and the design of local incentives that facilitate adoption.

At the policy level, the findings are directly relevant to CAP instruments and rural revitalisation strategies. Liquorice fits within eco-schemes promoting soil regeneration, perennial crops, and reduced input systems, and could be supported through EAFRD measures targeting diversification, short supply chains, and social farming initiatives. The alignment between high suitability and demographic vulnerability also offers a concrete pathway for integrating bio-based value chains into national and regional agendas addressing depopulation (e.g., RDAs, LEADER groups, España Vaciada strategies). Furthermore, the crop’s potential contribution to circular bioeconomy objectives reinforces its suitability for inclusion in regional smart-specialisation strategies and EU bioeconomy frameworks.

Through linking environmental potential with socioeconomic opportunity, liquorice cultivation in Spain can contribute significantly to a diversified, regenerative, and resilient agri-food model. Moreover, the replicability of the GIS methodology developed in this study allows for its adaptation to other crops or regions, offering a valuable decision-support tool for territorialized agricultural planning and identification of untapped opportunities.