Effect of Farm Size on Sustainability Dimensions: Case of Durum Wheat in Northern Tunisia

Abstract

The sustainability analysis of wheat farms is increasingly becoming interesting for the scientific community in order to help propose a production model ensuring food security and sustainability of agricultural production. This work aims to assess cereal farms’ sustainability in Northern Tunisia via analyzing the effect of farm size on sustainability dimensions. Toward this aim, the Farm Sustainability Indicators (IDEA) method and statistical tests (ANOVA, LSD) were used for the analysis of the obtained data from a representative sample consisting of 200 farms—located in the governorates of Beja, Jendouba and Bizerte—with different sizes (<5 ha; 5–20 ha and more than 20 ha). The IDEA method is built from three indicators of sustainability (environmental, social and economic) in agriculture. The results showed a very high variability in the sustainability scores of durum wheat farms. In fact, the scores relating to each sustainability dimension vary according to the farm size. Overall, the results highlight that small farms are the most economically vulnerable despite being friendly to the environment. However, large farms were relatively more viable, but less environmentally friendly.

1. Introduction

In Tunisia, the production of cereals faces multiple challenges. Cereals are considered staple foods in Tunisians’ diet, providing 52% of total calories and 53% of total protein. According to National Institute of Statistics (INS) data from 2020, Tunisians are major cereal product consumers with a per capita consumption of 174 kg/year [1]. The cereal policy designed and followed since independence has evolved from a state volunteerism, targeting the intensification and modernization of the agricultural production to best control the sector, to a distributive economy, in favor of consumers, and finally, to a “protectionist liberalism” in which the control of the sector is largely managed by the state. It is widely recognized that food security is strongly linked to the development of the cereal sector as far as it represents a basic and a strategic agricultural product.

The cereal sector is by far the largest contributor of the agricultural sector. Cereal cultivation totals nearly 33% of the useful agricultural area (UAA) and comprises around 248,500 farms (50% of the total number of farms), in which barley is grown in 11,542 farms larger than 50 ha (5% of farms, holding 40% of the land) while farms smaller than 10 ha represent only 63% of the total workforce [2]. Cereal production contributes an average of 13% to the agricultural added value and supplies materials to several other agricultural and industrial sectors. It is a major source of feed for livestock through its products, byproducts and sub-products and feeds various processing chain such as flour and semolina mills.

Additionally, this sector has a key role in strengthening the stability of rural communities by preserving agricultural employment. Cereal farming provides 2.5 million working days annually, or 9% of total agricultural employment in Tunisia [3].

Cereals production is also important for crop rotation and helps protect more than 1000 thousand hectares against erosion during the growing cycle, which is spread over 7 months, consequently protecting the watersheds compared to fallow, particularly under increasing pressure on natural resources such as soil and water, often leading to the resilience of various ecosystems [4]. However, the income from cereal farming is dependent on the world market and characterized by an increasing price volatility and fluctuating supply (as a result of climate change), political and economic upheavals in the country and expanding demand for population growth and food transition caused by changing consumer habits. Therefore, it is important to assess the sustainability of cereal farms in order to ensure national food security by reducing the food balance deficit (30% in 2021) and cereal deficit (43% in 2021) by implementing suitable strategies and shifting from productive to sustainable cereal production models.

Measuring the sustainability of farms using different indicators is a key tool for shaping suitable strategies and assessing their consequent impact [5]. In most used methods, the evaluation criteria at the farm level should be in agreement with the three specific sustainability dimensions reported by [6]: being sustainable means economically viable, socially equitable and ecologically reproducible.

Various methods and indicators were previously proposed for measuring and assessing the sustainability of farms. At least sixty indicator-based sustainability measurement methods have been developed [7]. Previously, Moller et al. (2014) estimated the sustainability of cereal farms using the Agricultural Production Systems Simulator Model (APSIM) [8]. Calabresse et al., in 2016, compared potato and wheat production systems using only two dimensions of economic and environmental sustainability in Switzerland [9]. In agriculture, this triptych has sometimes evolved into a four-dimensional version: viability, livability, reproducibility and transmissibility. According to Feschet et al. (2014), several French multi-criteria evaluation methods applied to agricultural systems have been the subject of an in-depth analysis [10]. Recently, Refs. [11,12,13] showed significant diversity in methods based on sustainability indicators. Among these, the IDEA method [14,15,16] is actually one of the widely used sustainability assessment methods in the European Union [17]. Attia et al. (2021) evaluated and compared the sustainability of small-sized dairy cattle farms belonging to three farming systems (rainfed, irrigated and mixed) located in Northern Tunisia [18].

Various researchers analyzed the sustainability of wheat crop production [17,19,20,21,22,23,24,25,26]. However, the effect of the farm size has not been considered so far. Nevertheless, recently, Fallahinjed et al. (2022) studied the effect of farm size on sustainability of wheat production in Iran using the emergy approach [25]. The authors noticed higher yield/unit area using less renewable environmental resources produced in large-sized farms compared to small- and medium-sized farms. Previously, the focus of the research was mainly concentrated on the effect of farm size on the technical efficiency; however, few have analyzed the effect of farm size on cereal crop sustainability [27,28]. The diagnosis of cereal farms targets the analysis and identification of the causes of the dysfunction of this sector and helps design solutions and shapes suitable strategies against the main constraints hampering farm performance at the technical, social, economic and environmental levels.

In Tunisia, sustainability has previously been the subject of several works of agricultural research. M’hamdi et al. (2009) assessed the sustainability of dairy farms [29]. Lajimi et Ben Nacer (2009) compared the sustainability of organic and conventional oil-producing farms [30]. Bouzaida et al. (2019) assessed the sustainability of irrigated farms in arid Tunisian areas [31]. Ben Abdallah et al. (2020) assessed the environmental sustainability of oil olive cultivation [32]. Attia et al. (2022) assessed and compared the sustainability of small-sized dairy farms for cattle farming in the North of Tunisia [33]. However, to our knowledge, no studies dealing with cereal sector, specifically durum wheat in Northern Tunisia using in-depth statistical analyses, were conducted. In order to fill this gap, we have contributed to answering the following research question: Does farm size affect the sustainability of durum wheat production?

Although the effect of farm size has been largely assessed in different agricultural systems, the determination of the sustainability of durum wheat farms under sub-humid climatic conditions (the most favorable areas for cereal crops) using the Farm Sustainability Indicators (IDEA) method has not been previously undertaken. Therefore, different hypotheses were proposed as follows:

H1: 

The farm size affects the total sustainability score similarly;

H2: 

The three sustainability dimensions are affected differently by the farm size;

H3: 

The small-sized farms are economically sustainable.

2. Methodology

2.1. Method for Assessment of Farms’ Sustainability (IDEA)

The IDEA method was used to estimate the sustainability of cereal farms under the sub-humid climatic conditions of Tunisia. This method was designed and optimized to serve as a decision-making tool. The used data were provided voluntarily and anonymously by the interested parties [33]. Indicators generally provide an overview on dependent variables that are more difficult to access. They also serve as a benchmark for making a decision [34].

Initially, the IDEA method was proposed as an educational tool suitable for agricultural education and farmers to introduce the concept of measurable sustainable farming. Since then, its use has gradually expanded to other purposes such as research, support for change and advice for agricultural development. Indeed, this method was revised twice in 2003, and then again in 2008. The IDEA Scientific Committee conducted a research work which thoroughly renewed its conceptual framework, evaluative grids and indicators, culminating in the IDEA version4 (IDEAv4) method [7]. The main advantage of the IDEA method is its sensitivity, allowing us to observe differences in sustainability not only between different-sized farms but also within the same farm size and production system [35].

2.2. Identification of Sustainability Indicators

The IDEA method is based on several indicators covering the three dimensions of sustainability: economic, environmental and social. This method assigns a determinate score to each indicator. The total value of sustainability dimensions is the cumulative value of indicator scores and has a maximum value of 100 points.

$${\mathrm{Total} \mathrm{sustainability} }_{(\mathrm{Farm} \mathrm{j})} ={\displaystyle {{\displaystyle \sum }}_{k=1}^3}dimensio{n}_k\left({{\displaystyle \sum }}_{i=1}^{n}score{s}_i\right)$$

where: k is the dimension of sustainability;

• i is score of indicators;
• j is the number of the farm.

2.2.1. Economic Sustainability Indicators

The economic sustainability scale is composed of 8 indicators.

Table 1. Economic Sustainability Indicators.

Indicator	Formula	Modality	Score
Economic efficiency	Value added/Products of activity	<20%–>60%	0–5
Economic autonomy	Global Gross Margin/Product of Activity	<55%–>75%	0–5
Financial autonomy	(Total non-land annuities)/Consolidated gross operating surplus	>65%–<25%	0–5
Capital efficiency	Social Income/Operating Capital	<5%–>25%	0–5
Work remuneration	Social Results/(Added Value—subsidy)	<30%–>70%	0–5
Commercial vulnerability	Specialization Rate—Gross Product of Main Production/ (Product Activity—Aids)	>80%–<65	0–5
Diversification opportunities	The most important customer/Proceeds from the business	>70%–<60%	0–5
Sensitivity to government subsidies	Subsidies/Social Results	6	0–5
Total economic dimension value			33

defines these indicators, their calculation and their maximum value. The reported indicators were selected on the basis of a literature review and also take into account our commodity case study (cereal). The total sum value of the scores is 33 points.

2.2.2. Social Sustainability Indicators

The social sustainability scale consists of seven indicators.

Table 2. Social Sustainability Indicators.

Indicator	Formula	Modality	Score
Viability	Quality of life		0–5
Viability Professional opening and social	Professional and social openness	Openness	0–3
	Training approach	Professional training = 1, training = 2, exchange group = 3	0–3
	Participation in agricultural working life	CUMA, OPA, farmers’ Union)	0–3
	Possibility to work in mutual aid	Number of public visits	0–3
	Participation in territorial social life	%	0–3
Work efficiency	Disposable income/family assets Per annual hours of work % of net hourly	<0.4 Agricultural Minimum Wage (AMW) hours- >2 AMW hours	0–5
Viability Socio-economic	Social income/UTH	5 Levels	0–5
Transmissibility	Capital operating (off land)/UTH	5 Levels	0–5
Territorial anchorage	Transformation	1 = yes, 0 = no	0–1
	Direct sale	1 = yes, 0 = no	0–1
	Tourist or social reception	1 =yes, 0 = no	0–1
	Open to the territory: hosting schools, agricultural groups, cultural events, etc.	1 = yes, 0 = no	0–1
	Development and maintenance of built heritage	1 = yes, 0 = no	0–1
Social return	Social result/ha	5 Levels	5
Foodprint Land	Total Area Mobilized/UAA	>140%–100%	5
Total social dimension Value			33

Available income—EBITDA—annuities—short-term financial expenses; Guaranteed agricultural minimum wage (SMAG) is 13 dinars 736 millimes per day or 4284 DT/year (1302 euros/year).

defines these indicators, their calculation and their maximum value. The maximum total value for social sustainability dimension is 33 points.

2.2.3. Environmental Sustainability Indicators

The environmental scale involves 9 indicators.

Table 3. Environmental Sustainability Indicators.

Indicator	Formula	Modality	Score
Mineral Balance or disagree	Nitrogen units per ha of UAA	>100 uN/ha–<20 uN/ha	0–5
Degree of pollution induced by the amount of herbicide (IFT)	Quantity of herbicides used/ha	>= 1-0	0–5
		>= 1-0
IFT Pesticides, outside Herbicides	IFT exploitation excluding herbicides, % of the Reference	>= 1-0	5
		>= 1-0
Biodiversity	Presence of intercultural bands in cereal preserving biodiversity Presence of untreated honey crops Mechanical destruction of natural plants Creation and maintenance of hedges without chemical weeders Use for hedgerows of local or rare or endangered species No GMO cultivation or purchase of GMO food Preservation and maintenance of wetlands	1 = yes, no = 0	0–1
		1 = yes, no = 0	0–1
		1 = yes, no = 0	0–1
		1 = yes, no = 0	0–1
		1 = yes, no = 0	0–1
		1 = yes, no = 0	0–1
		1 = yes, no = 0	0–1
Soil and water conservation	Soil conservation Water conservation	1 = yes, no = 0	0–1
		1 = yes, no = 0	0–1
Soil management	% Area ground/UAA	>10%, 0.1 to 2.5%	0–5
Soil management: rotation	% of the same annual culture into the surface	>30%, 15 to 20%	0–5
Energy dependence	Total fossil fuels. (EQF)/ha UAA	>600 EQF–<200 EQF	0–5
Net contribution warming up climatic	Total Equivalent (Teq) C02/ha UAA	>5.5 TeqCO2/ha–1.5 to 2.5 TeqCO2/ha	0–5
Value of total environmental dimension			33

defines these indicators, their calculation and their maximum value. The total sum value of the scores of the environmental sustainability scale is 33 points.

2.3. Study Area

The technical and socio-economic diagnosis concerned the three main cereal governorates of the country in terms of durum wheat production. The three governorates (Beja, Bizerte and Jendouba) are located in the sub-humid zone of the country, the most favorable zone for cereal production, particularly durum wheat (Figure 1). This area is characterized by rainfall between 500 and 700 mm/year.

In terms of area, these regions account for 13% of UAA; cereal farming occupies nearly 50% of the arable area. Durum wheat is grown to take up 70% of the cereal area. The three regions account for 46% of Tunisia’s durum wheat production (

Table 4. Distribution of cereal areas and farmers.

	Beja	Bizerte	Jendouba	Tunisia
UAA (1000 ha)	258	215	168	4884
% UAA/T. Tunisia	5.3%	4.4%	3.4%	100%
Cereal area (1000 ha)	144	92	82	1610
% Cereal area/UAA	56%	43%	49%	33%
Durum wheat (1000 ha)	93.1	64.6	60.6	858
% Durum wheat/Total Cereal	65%	70%	74%	53%
Total farmers	21,200	21,740	24,960	515,850
% Cereal farmers	4.1%	4.2%	4.8%	100%

MARH, 2019.

). It is also noted that it is the oldest area used for the cultivation of wheat.

In this work, a questionnaire survey was carried out among 200 cereal farms in 2020 in the three governorates of Beja, Jendouba and Bizerte. The surveyed farmers were selected according to the size and the type of farms. This is a stratified sampling spread over the three regions and stratum of durum wheat area (0–5 ha; 5–20 ha; and more than 20 ha). The choice was made with the heads of the Regional Agricultural Development Commissions (CRDA) in order to have an equal distribution between the different strata and regions. However, given the difficult conditions encountered during the course of the survey, we reduced the sample to 200 durum wheat producers, taking into account the size of the farms and their production.

3. Results

3.1. Assessment of Sustainability Dimensions by Farm Size

All farms that were surveyed in the three different sub-humid regions produce cereals. The obtained results from the IDEA method reveal that the overall sustainability of farms is, on average, 61.37. The total score is 61, 59 and 64 points, respectively, for farm sizes of 0.1–5 ha, 10–20 ha and >20 ha (

Table 5. Farm sustainability scores by size.

Sustainability/Size		N	Average	Standard Deviation
Total Sustainability *	<5 ha	84	60.86	14.54
	5–20 ha	64	59.37	16.60
	More than 20 ha	56	64.41	16.80
	Total	204	61.37	15.89
Social Sustainability	<5 ha	84	20.82	5.02
	5–20 ha	64	21.67	5.87
	More than 20 ha	56	25.70	6.23
	Total	204	22.43	5.98
Environmental Sustainability	<5 ha	84	24.57	4.72
	5–20 ha	64	23.62	7.25
	More than 20 ha	56	21.66	7.56
	Total	204	23.48	6.51
Economic sustainability	<5 ha	84	15.46	9.23
	5–20 ha	64	14.08	8.91
	More than 20 ha	56	17.05	7.83
	Total	204	15.47	8.80

* Total sustainability is calculated as the sum of the average of the three dimensions scores.

). These results show a very high variability in sustainability scores for the surveyed farms. The total sustainability of cereal farms is low and ranges from 30 to 80.

Regarding these scores by dimensions, the lowest scores were recorded in the economic sustainability dimension. The average scores for social, environmental and economic sustainability were 22, 23 and 15, respectively. These scores varied from 12 to 38, from 14 to 61, and from 0 to 30 for social, environmental and economic sustainability, respectively (Table 5).

3.2. Economic Sustainability

The economic sustainability is the lowest compared to other scales. This is confirmed for all categories of farms.

Economic sustainability is shown in Figure 2. The IDEA method has shown that the sensitivity of cereal farms to aid is medium. In addition, the majority of indicators related to the surveyed cereal farms, namely economic efficiency, financial autonomy, capital efficiency and labor compensation, are average. However, the two indicators that pose challenges for economic sustainability are diversity and trade vulnerability. This is normal since the production of cereals is an activity administered by the cereals board, which is the only operator in the national market.

In terms of economic sustainability, large farms were the most successful (Figure 2) and economically efficient, with greater capital efficiency and more flexible financial autonomy than small- and medium-sized farms. It should be noted that small-sized farms with an area of less than 5 ha are more economically viable than medium-sized farms (5 to 20 ha).

3.3. Social Sustainability

Social sustainability is more respected in the group of large farms due to additional means to open up to their social environment. Likewise, these farms have a significant employability capacity and high staffing rates.

For social sustainability, the axis of the land footprint is the most respected. Indeed, the land-use rate in these regions is 100%. On the other hand, the other variables, represented by occupational openness, workforce, socio-economic viability and transmissibility axis and territorial anchoring, are weak.

For the environmental sustainability, shown in Figure 3, cereals do not cause a problem regarding global warming similar to any other agricultural activity. Thus, this activity, although it is mechanized [35], does not affect energy dependence. However, the mineral balance indicators, the herbicide and other pesticides use index, soil and water conservation work (SWC), biodiversity and rotation are poorly respected.

3.4. Environmental Sustainability

Figure 4 highlights the environmental sustainability scale by farm size. The environmental sustainability is more respected in small farms than in large ones. They are the most protective against biodiversity and limit the use of pesticides. This could be explained by the lack of financial capacity to buy the required amount of very expensive pesticide input [36].

3.5. Multiple Comparison of Sustainability and Farm Size

In order to test the effect of farm size on the different dimensions of sustainability, the multiple comparison LSD test was used. This test showed that the difference in social sustainability is significant between the large-farm group (more than 20 ha) and the other two groups (<5 ha and 5–20 ha). For environmental sustainability, the difference is only statistically significant (at 5%) between large- (more than 20 ha) and small-sized farms (<5 ha). On the other hand, the difference in economic sustainability is statistically significant at 10% between the small-, medium- and large-farm groups (

Table 6. Multiple comparison of sustainability pillars and farm size LSD test.

Dependent Variable/Size			Difference in Means (I–J)
Total Sustainability	<5 ha	5–20 ha	1.48
		More than 20 ha	−3.55
	5–20 ha	More than 20 ha	−5.04 *
Social Sustainability	<5 ha	5–20 ha	−0.85
		More than 20 ha	−4.88 **
	5–20 ha	More than 20 ha	−4.03 **
Environmental Sustainability	<5 ha	5–20 ha	0.95
		More than 20 ha	2.91 **
	5–20 ha	More than 20 ha	1.96
Economic Sustainability	<5 ha	5–20 ha	1.39
		More than 20 ha	−1.59
	5–20 ha	More than 20 ha	−2.98 *

* The difference is significant at level 0.10. ** The difference is significant at level 0.05.

).

4. Discussions

The knowledge of the relationship between sustainability and farm size is essential for the development and implementation of suitable agricultural strategies and policies in Tunisia, especially regarding strategic crops such as wheat [35,37].

Our study of the relationship between the sustainability of wheat production and the size of farms aims to highlight the effect of farm size on sustainability and to put in place a targeted strategy for sustainable development in accordance with economic, environmental and social components. The results of this work showed that the durability scores ranged from 59% to 64%, which is in agreement with the study of [18,30,32], who previously estimated the sustainability of Tunisian farms.

The results obtained show a great variability in the scores of sustainability according to the size of farms. In fact, the relationship between scores of sustainability of durum wheat production and farm size was confirmed. Therefore, our three study hypotheses are accepted.

Total sustainability of durum wheat in Northern Tunisia ranged from 54 to 64%. This is similar to that of Italy, where durum wheat is the most cultivated cereal [19]. In both Mediterranean countries, durum wheat is essential in the diet, being the basis for the processing of different products such as pasta, couscous, bulgur and bread. Furthermore, the level of sustainability of Iranian wheat is similar to those of Italian and Tunisian wheat [30,36,38,39].

Our results also showed that the lowest scores were noticed at the economic scale in agreement with the results of [18], who showed that the rainfed system prompted average performances of the three dimensions and that the lowest scores are observed at economic scale. The results also showed that the relationship between farm size is significant regarding the three dimensions of sustainability. However, [18] results showed that the socio-territorial scale was the limiting factor for all systems and that the irrigated system exhibited the lowest scores of environmental and social scales, compared to others, but it recorded the highest score for the economic dimension. The mixed system exhibited the highest environmental and social scores but also the lowest score regarding the economic scale. Finally, the rainfed system showed medium performances for the three sustainability scales.

The social sustainability scores were higher than the economic scores. This result is in concordance with the studies conducted by Attia et al. (2022) [18]. It is justified by the education level of farmers in Tunisia [29].

The economic aspect and, in particular, the profitability of wheat production and sustainable agriculture are highly criticized in the literature [27]. In Tunisia, the aspects to be improved are mainly related to institutional and political orientations to support cereal-based systems and make them sustainable. Thus, the sustainability of wheat production can be achieved by adjusting agricultural behavior to more sustainable practices and by modulating the policies of decision makers. In fact, improving the incomes of wheat producers could be a priority through direct aid [32] and/or through the liberalization of wheat prices [35], which must be adjusted at least to international market prices.

The results showed that there was no difference between the three farm sizes on the economic scale, which was different from that of M’Hamdi et al. (2009), who found that the economic scale presented significant variability between dairy farms [29]. However, market diversification and commercial vulnerability, which are two components of the economic scale that assesses the efficiency of the grain market, were nil. This is explained by the state policy which monopolizes the durum wheat market.

The IDEA method can be adapted in different case studies. Moreover, advanced statistical methods can be used to improve the robustness of the obtained results.

Despite the significance of the obtained results, this study presents also some limitations. First, the IDEA method is based on subjective indicators and improved methods could be considered for better estimation of these indicators. Additionally, the data should be collected and analyzed using multiple analytical methods rather than a single method. Finally, these results are limited to a sub-humid climate condition and should be extended to cover this behavior in other regions under different climatic conditions.

5. Conclusions

This work presents the assessment results of the sustainability of durum wheat farms in the different sub-humid regions of Northern Tunisia based on cereal-producing farms’ surveys assessed following the IDEA method.

This study confirmed the hypothesis of the global sustainability of durum wheat production in northern Tunisia. The results obtained showed a great variability in the scores of sustainability according to the size of the exploitation. Large farms are generally more sustainable than the other two groups. Indeed, the scores relating to each sustainability dimension (social, environmental and economic) varied according to farm size. However, the hypothesis regarding the relationship between farm size and sustainability was confirmed. Therefore, targeting specific interventions for each category of farm according to the failing indicators is of great importance.

According to the assessment of economic sustainability scores (commercial vulnerability, market diversification), the government should be releasing the wheat prices and markets, especially of durum wheat, in order to improve these scores. In addition, based on the lowest score of economic autonomy, reducing credit constraints is also suggested regardless of the farm size.

Encouraging farmers to join farmers’ associations and scaling up extension services are also suggested, especially to small farms, to strengthening the social scale of sustainability.

Finally, from an environmental sustainability perspective, the use of pesticides should be carefully considered, especially in large-sized farms. In this regard, to improve environmental sustainability, the promotion of precision agriculture, crop rotation and implementation of best practices and soil conservation are crucial and highly recommended.