Geographical Variability of Set-Aside in Poland: Environmental and Anthropogenic Impacts on the Implementation of Complementary EU Instrument

Abstract

The aim of this paper is to determine whether the complementary instrument of agricultural cyclical set-aside has been implemented in Poland over the past decade (2014–2023). Additionally, this study examines the geographical variability in the set-aside application and identifies factors that contribute to this spatial variability. Geographically Weighted Regression is employed to capture the spatial variation in environmental and anthropogenic factors influencing set-aside measures. Findings confirm that rotational set-aside practices vary across Polish municipalities. Negative impacts on set-aside measures are associated with the following independent variables: farm size, environmental protection, low-quality soils, water surface, and social capital. However, the magnitude and significance of these impacts vary spatially. Geographically differentiated impacts are observed for variables such as length of the growing season, precipitation, mineral fertilizer consumption, and slope of the terrain. Interestingly, a general positive influence is not confirmed for any predictor regarding the frequency and extent of set-aside practices. The findings suggest reconsidering and emphasizing the geographical aspects of the Common Agricultural Policy within the European Union.

1. Introduction

Set-aside is the practice of removing arable land from crop production for one or more years, allowing it to regenerate naturally or be sown with a seed mixture [1]. Set-aside can be either cyclical (rotational), lasting for a single season, or non-rotational, applied over a longer term [2]. This paper focuses specifically on cyclical set-aside practices.

Throughout history, land has been associated with wealth and stability, with fertile land being crucial for agricultural income. As land resources became scarce, farmers left some undeveloped land to improve soil fertility and maximize future yields [3]. Set-aside land is a field excluded from agricultural use, most often for a period of one to two years, on which appropriate mechanical or chemical care is performed.

Set-aside should not be identified with fallow land, i.e., space left in an extensive economic condition in its natural state, which does not improve but reduces the production properties of the soil. Fallow land should be understood as land left without intervention for a period of more than one year [4,5]. The long-term or even permanent exclusion of agricultural land from use is a common phenomenon and is the result of many reasons, but mainly of the lack of profitability of cultivation [3,4].

The cyclical agricultural set-aside is regarded as one of the methods employed to reconcile the efficiency of modern agriculture with the priorities of landscape and environmental protection, particularly biodiversity. Initially used as a mandatory measure to address agricultural overproduction in the EU, the setting aside of arable land has been more recently justified on environmental grounds and proposed as a complementary tool within the framework of the EU Common Agricultural Policy. Consequently, according to Article 4.4.c of Regulation (EU) 2021/2115 of the European Parliament and of the Council of 2 December 2021 Establishing Rules on Support for Strategic Plans… [6], EU member states have the discretion to designate eligible hectares, including areas used for agricultural activities only every two years. Spatial disparities in the implementation of this measure are hypothesized, even within individual countries.

The reasons for land set-asides are rather diverse and of both environmental and anthropogenic nature. Furthermore, the decision to exclude certain areas of production stems from both internal farm conditions and external factors [3]. Investigation of the geographical variability of the set-aside application and identification of the factors that contribute to this spatial volatility is the aim of this paper.

2. Theoretical Framework

2.1. Set-Aside Tradition in Poland

In Poland, set-asides were an integral part of land use systems from the beginning of the development of agriculture until the mid-19th century, when the previous fallow system was replaced by crop rotation in a three-field scheme, where farmers alternated between planting crops and leaving one field fallow, ensuring long-term productivity of the soil [4,7]. At that time, the Norfolk crop rotation system was introduced. According to it, the field previously designated for fallow was used for root crops grown on manure and perennial legumes, which enriched the soil with nitrogen bound from the air and, by shading the soil, effectively inhibited the growth of weeds [7].

During the communist era, until 1989 agriculture in Poland was heavily influenced by Soviet-style collectivization. Large state-owned farms, so-called “PGR” (Państwowe Gospodarstwo Rolne—State Agricultural Farm), focused on maximizing production, often at the expense of environmental sustainability. The concept of set-aside land was largely abandoned during this period, as the land was intensively farmed without regard to soil conservation or crop rotation practices. However, in rural areas where small private farms persisted, some fallow land practices were maintained out of necessity or tradition [8,9,10,11]. Since 1991, due to agricultural restructuring, the area of unsown fields has been systematically increasing [12].

Before the accession of Poland to the European Union and the implementation of area payments, there was a notable reduction in fallow land within the agricultural landscape. Previously, particularly in the 1990s, fallow land was widespread, especially in regions where a large area of the land was owned by the state [3]. Poland’s accession to the European Union in 2004 marked a significant turning point for set-aside land practices. Set-aside land was seen as a way to enhance biodiversity, combat soil erosion, and improve water quality. Many Polish farmers embraced these policies, as they provided economic benefits while also encouraging more sustainable farming methods. By 2008, the EU decided to phase out mandatory set-aside requirements, though farmers were still encouraged to implement environmentally friendly practices under other greening measures. These measures required farmers to maintain ecological focus areas, crop diversification, and permanent grassland, indirectly promoting land conservation without formal set-aside mandates [13].

2.2. Set-Aside as a Complementary Instrument of EU Agricultural Policy

The Common Agricultural Policy (CAP) in the 1970s and 1980s definitely had market orientation goals [14]. The MacSharry reform in 1992 marked the first formal recognition of the need for a more eco-friendly approach to European agriculture, e.g., it introduced a mandate for farmers to set aside 15% of their cultivated land from food production [15,16,17,18]. The reason for introducing the new EU agricultural policy was the surplus in agricultural production [19], and the excessive cost of previous EU agricultural policy actions [20]. For example, between 1993 and 1994, 6.4 million ha of land were set aside within the European Union countries under the Set-Aside Land Option program, and the scenarios for changes in the use of agricultural land in Europe assumed a further increase in the area of land excluded from agricultural production [17,21]. While the research shows, the expansion of set-aside land under the CAP has reduced the area vulnerable to soil erosion in certain parts of Europe, the agricultural regions in central Spain have seen the opposite effect [22]. In addition, the negative impact of promoting voluntary and implementing obligatory set-aside in Spain on the technical efficiency of agriculture should also be noted. As a result, the reform in Spain provided farmers with an option for early retirement [23]. The French example indicates that a set-aside subsidy can incentivize farmers to intensify production, potentially leading to negative environmental impacts. However, these impacts can be mitigated through the implementation of a complementary tax policy instrument [24].

The obligation to set aside agricultural land was introduced into the European Union as a supply control mechanism. It was regulated by the market situation in the arable crop sector. Set-aside agricultural subsidies were established in 2003, which resulted in the granting of direct payments, assuming that the land is not used for production purposes, but is maintained in good agricultural condition, consistent with environmental protection [25]. The area of arable land required for mandatory set-aside was reduced to 10% in 1996 and eventually eliminated in 2008. These changes had an immediate impact on the amount of fallow land in Europe, which initially doubled, but then steadily decreased after 2010. Then, the 2014–2020 CAP introduced ‘greening measures’ that required farmers to undertake actions to enhance biodiversity. For farms of 15 hectares or more, one of these measures mandates that 5% of arable land be set aside as ecological focus areas, with set-aside being one of the permissible options [18].

According to the CAP and Green Deal policy for the 2023–2027 period, if the arable land on a farm covers an area exceeding 10 ha, at least 4% of this land area is designated for nonproductive areas or facilities, including set-aside areas. However, in 2024 the European Commission published a regulation allowing for a derogation from the application of the GAEC 8 standard, regarding the requirement to allocate a minimum of 4% of arable land to nonproductive areas [26]. Furthermore, differences in national agricultural policies could influence the regional effectiveness of set-aside land [27].

2.3. Environmental and Anthropogenic Factors Influencing Set-Aside Practices

The authors focus on factors influencing land abandonment rather than set-aside [28,29,30]. This is likely due to the permanent nature of land abandonment in terms of land use and land cover, compared to the temporary nature of set-aside, which seems to be less significant from a planning perspective. Nonetheless, the need for a geographical analysis of the factors influencing set-aside is crucial for both agricultural and planning purposes. Understanding the spatial determinants of set-aside enables improvements in agricultural policy. Primarily, it helps identify the characteristics of areas where set-aside practices are voluntarily implemented and highlights areas of a different nature where set-aside should be promoted or even regulated. This approach aligns two important EU frameworks: agricultural policy and territorial cohesion.

Set-aside is commonly included in national and international regulations and is also required by voluntary sustainability certifications [2,29,31]. The motivation to incorporate set-asides into policy frameworks is typically environmental. However, policymakers must be cautious not to allow set-aside programs to shift responsibility from the actual polluters to farmers [32].

The set-aside of agricultural land allows for the recovery of natural ecosystems, promoting biodiversity and reducing the strain on soil by giving it time to recover from continuous cultivation [22]. They may also be related to the low production potential of the soil, resulting from low soil quality classes, erosion, or negative influences of neighboring areas [4,10,19,33,34]. It is also confirmed that set-aside practices are predominantly implemented in areas of high precipitation and impermeable soils as part of a strategy to mitigate flood effects since set-aside land absorbs excess rainwater much more effectively than cultivated agricultural land [22,35]. On the other hand, set-aside is also a practice used to mitigate the negative effects of drought, particularly in areas with limited access to surface water and groundwater [36,37]. As a consequence, the complex and non-linear impact of precipitation on set-aside practices should be underlined [34]. Moreover, the influence of the growing season length on farmers’ willingness to adopt set-aside practices is evident: the shorter the vegetation period, the greater the demand for adaptive strategies such as set-aside [38].

Rotational set-aside is required primarily in areas where agricultural expansion significantly affects climate change and habitat loss, yet cannot be excluded from agriculture for social and economic reasons [20,31,39,40]. Consequently, set-aside is recommended mainly in sloped areas near rivers characterized by high precipitation. The aim is to protect soils and watersheds, and, as a result, to preserve natural habitats both on slopes and within rivers [31,41]. A similar approach can be applied to protected areas, where environmental protection objectives encourage environmentally oriented agricultural practices, including set-aside [32]. On the other hand, the need for set-aside is much higher in relatively simple landscapes than in complex ones [17,18,42].

Anthropogenic factors encompass the following contexts of set-aside determinants: agricultural, socio-economic, and policy-related. In addition, anthropogenic impacts are closely linked to environmental issues. For instance, addressing challenges such as habitat loss or climate change necessitates large-scale cooperation across farms and boundaries [20,39]. Therefore, the social capital within rural communities can significantly enhance the willingness to adopt set-aside practices and improve the effectiveness of these practices.

The commercial vs. semi-commercial character of agricultural production is considered a factor differentiating the willingness of farmers to apply set-aside practices. However, the significance of the aforementioned factor is disputable [43]. Nevertheless, set-aside practices are significantly influenced by farmers’ attitudes toward agricultural schemes. These attitudes may vary economically, with some farmers focused on the financial appeal of the schemes (profit-motivated or profit-influenced attitudes), while others prioritize the schemes themselves rather than profit (scheme-influenced or peer-influenced attitudes, reflecting a farmer’s susceptibility to the opinions of others) [44].

Regarding anthropogenic factors: socio-economic and agricultural contexts are interdependent to some extent. For example, set-aside practices might result from the lack of opportunities to obtain agricultural income, and low profitability of agricultural production may result from the large dispersion of plots or lack of labor [3,4,19]. Moreover, when farmers’ financial motivations are limited, set-aside can be considered a component of the post-productivist phase in agriculture [40]. Set-aside practices are driven by farmers’ need to support farm survival and generational continuity, achieved through diversified income sources and optimized labor allocation [45].

It is important to note that the aforementioned anthropogenic factors are highly subjective and difficult to quantify. As a result, its direct application in quantitative research is considerably limited. However, there is strong evidence that the prominence of profit in agricultural activities is positively correlated with farm size, particularly since larger farms are less reliant on subsidies [46]. Consequently, using farm size as an indirect economic variable in set-aside research is justified. On the other hand, the 2014–2020 CAP introduced ‘greening measures’ requiring farmers to implement actions aimed at increasing biodiversity. One such measure mandates that farms of 15 hectares or more designate 5% of their arable land as ecological focus areas, with set-aside being one of the options [18].

From an agricultural perspective, there is a significant negative correlation between the use of fertilizers and pesticides and the implementation of set-aside practices [17,39]. The farmers’ willingness to reduce the use of both fertilizers and pesticides drives them to seek alternatives that maintain the technical efficiency of agriculture. Consequently, in areas where the use of fertilizers and pesticides is restricted, set-aside practices are expected to be more prevalent. Additionally, it makes economic sense to designate less productive land for set-aside [47,48]. Therefore, the less productive the soils, the higher the probability of implementing set-aside practices. Moreover, crop-related factors and specific crop risks play a significant role in farmers’ decisions regarding the implementation of rotational set-aside practices [49]. However, including these factors in this study is challenging due to missing data for quantitative measures.

Based on the literature review, we propose the following factors (and respective measures—see

Table 1. Environmental and anthropogenic factors influencing set-aside practices and their measures.

The Nature of the Factor Influencing Set-Aside Practices	Factor Influencing Set-Aside Practices (Abbreviation)	Measure to Be Used for Poland	Hypothesized Impact
Environmental	Slope of the terrain	Average slope of the terrain in the municipality [%]	Positive [31,41]
	Water surface	Water surface rate in the total area of land in the municipality [%]	Positive [22,35] or negative [36,37]
	Low-quality soils	Share of low-quality soils (initial soils, podzolic soils, rankers, regosols, rusty soils) * in the total area of arable land in the municipality [%]	Positive [4,10,19,33,34]
	Precipitation	Average amount of precipitation in the municipality [mm/1 m2]	Positive [22,34,35] or negative [34,36]
	Growing season	Length of the growing season [days]	Negative [38]
	Environmentalprotection	Share of protected areas in the total area of municipality [%]	Positive [32]
Anthropogenic	Farm size	Average farm size in the municipality [ha]	Positive [18] or negative [46,50]
	Social capital	The number of NGOs operating in the municipality [number per 1000 inhabitants]	Positive [20,39]
	Consumption of mineral fertilizers	Average consumption of mineral fertilizers [kg per ha]	Negative [17,42,51]

Source: Chief Inspectorate of Environmental Protection [52]; Head Office of Geodesy and Cartography [53]; Statistics Poland [54]; Sykula [55]; Tomczyk and Bednorz [56]; Tomczyk and Szyga-Pluta [57]. Comment: * Selection of low-quality soils was proposed based on the Polish Soil Science Society, Commission of the Origins of Soil Classification and Cartography [58] and Smreczak and Łachacz [59].

) that may potentially influence set-aside in Poland to be considered in our research. The factors are both environmental and anthropogenic nature. Environmental factors include a slope of the terrain (expected to have a positive correlation with set-aside), water surface (positive or negative correlation), low-quality soils (positive correlation), and protected areas (also positive). Due to the complex nature of precipitation’s influence on set-aside, it cannot be hypothesized in a linear manner that its impact is either entirely positive or negative.

Anthropogenic factors include the following contexts of set-aside determinants: agricultural, socio-economic, and policy-related. Regarding socio-economic and policy-related impacts, average farm size could be proposed as an indirect measure, with a negative correlation expected regarding farmers’ willingness to implement set-aside (the larger the farm, the more focused it is on profitability). On the other hand, a positive correlation between this measure and the size of the set-aside could also be expected. This is because larger farms are more likely to implement actions aimed at increasing biodiversity, including set-aside practices (a direct result of EU regulations and incentives). The number of NGOs operating in the areas under investigation could serve as another socio-economic independent variable, representing the social capital of rural communities, including their capacity for cross-farm and cross-boundary cooperation required for effective set-aside practices. Agricultural factors correlating negatively with set-aside include consumption of mineral fertilizers.

3. Methodological Framework

3.1. Data Collection and Processing

The study employs spatial units—hexagons with a total agricultural area of 10 hectares, which corresponds to the average farm size in Poland. For each unit, using data from the Topographic Objects Database BDOT10K [60], the occurrence and sequence of changes in arable land use from 2014 to 2023 are examined. The objective is to identify the optimal pattern of cyclical fallowing, characterized by the alternation of arable land with other land uses, such as grasslands. This scenario contrasts with the continuous presence of arable land, which indicates uninterrupted agricultural use, or the complete disappearance of arable land within a given spatial unit.

For each hexagon, the proportion of arable land relative to the total area is estimated annually for the period 2014–2023. The coefficient of variation is used to assess the average magnitude of change in arable land, while the number of changes within the period is simply counted (a value of 1 is recorded if the land use in a subsequent year differs from the previous year, and 0 if it remains the same, repeated for each year). This approach allows for the estimation of both the value and the frequency of changes. These measures are then normalized to a range between 0 and 1. The aggregate index of set-aside is calculated as the average of the normalized measures and is subsequently used in further studies.

It should be explained that the Agricultural Census in 2020 [54] provides a snapshot of set-aside areas at a specific point in time (see Figure 1). However, we chose to investigate the rotational set-aside process itself. It is evident that comparing a dynamic process with a static state is not meaningful and does not allow for the investigation of the issue of rotational set-aside. Therefore, we decided not to use data from the Agricultural Census to describe the dependent variable. However, the Agricultural Census was an important source of data describing the measures of the independent variables.

In the case of the econometric analysis of factors determining set-aside in Poland, the aforementioned index of set-aside is spatially aggregated to the municipal level. This approach has been applied due to the availability of data on investigated independent variables enabled by Statistics Poland [54]. Moreover, as data on certain independent variables are collected exclusively through the Agricultural Census, with the most recent census data available from 2020, the data for all other independent variables were also collected for 2020.

3.2. Methods of Analysis

The aim of this study is to examine the geographically differentiated impact of environmental variables (such as terrain slope, water surface, low-quality soils, precipitation, and environmental protection) and anthropogenic factors (farm size, social capital, and mineral fertilizer consumption) on the magnitude and frequency of set-aside practices, represented by an aggregate index of set-aside. Prior to the regression analysis, a correlation matrix and the Variance Inflation Factor (VIF) were calculated to address potential multicollinearity (see

Table 2. Correlation matrix and Variance Inflation Factors for variables influencing the magnitude and frequency of set-aside practices (2014–2023).

Correlation	Slope of the Terrain	Water Surface	Low-Quality Soils	Precipitation	Growing Season	Environmental Protection	Farm Size	Social Capital	Consumption of Mineral Fertilizers
Slope of the terrain	1.00	−0.08	−0.08	0.63	−0.15	0.29	−0.18	0.02	−0.39
Water surface	−0.08	1.00	0.01	−0.15	0.01	0.17	0.07	0.17	−0.08
Low-quality soils	−0.08	0.01	1.00	−0.05	0.03	0.13	−0.04	−0.08	−0.18
Precipitation	0.63	−0.15	−0.05	1.00	−0.04	0.09	−0.39	−0.12	−0.23
Growing season	−0.15	0.01	0.03	−0.04	1.00	−0.13	0.14	0.00	0.22
Environmental protection	0.29	0.17	0.13	0.09	−0.13	1.00	−0.08	0.11	−0.38
Farm size	−0.18	0.07	−0.04	−0.39	0.14	−0.08	1.00	0.18	0.30
Social capital	0.02	0.17	−0.08	−0.12	0.00	0.11	0.18	1.00	0.00
Consumption of mineral fertilizers	−0.39	−0.08	−0.18	−0.23	0.22	−0.38	0.30	0.00	1.00
VIF	2.14	1.10	1.10	2.01	1.18	1.32	1.42	1.10	1.48

Source: Own elaboration using R packages ‘dplyr’ [62] and ‘car’ [63].

). No significant correlations were identified among the independent variables. Furthermore, the VIF for all regressors was well below the critical threshold of 10 [61], indicating no risk of multi-collinearity in the estimated model with all considered variables.

Feature selection was conducted by the application of a random-forest-based algorithm called “Boruta” [64,65]. The iterative algorithm extends the dataset by adding at least five shadow variables, which are shuffled copies of the investigated variables. It then estimates Z-scores for all variables and compares the Z-score of each investigated variable with the maximum Z-score among the shadow attributes. Variables that have a lower Z-score than the maximum of the shadow variables are considered unimportant and removed from the dataset. Conversely, variables that outperform the shadow variables are marked as important. Shadow attributes are also removed at the end of each iteration. The process is repeated until all the variables are classified as either important, unimportant or tentatively important. In this particular case (see

Table 3. Relative importance of variables influencing the magnitude and frequency of set-aside practices (2014–2023).

Z-Scores	Mean	Median	Minimum	Maximum	Decision on Variable Importance: Confirmed, Tentative, or Rejected
Growing season	52.43	52.60	50.05	54.67	Confirmed
Farm size	47.04	46.82	44.84	48.97	Confirmed
Precipitation	36.93	36.94	35.75	38.46	Confirmed
Environmental protection	32.59	32.17	30.65	34.87	Confirmed
Consumption of mineral fertilizers	32.04	32.08	29.76	34.63	Confirmed
Slope of the terrain	28.18	28.36	26.60	29.82	Confirmed
Low-quality soils	13.68	13.81	12.44	14.74	Confirmed
Water surface	10.93	10.83	9.99	11.75	Confirmed
Social capital	10.37	10.23	8.32	11.93	Confirmed

Source: Own elaboration using R package ‘boruta’ [64,65].

), all variables were confirmed as potential predictors of the magnitude and frequency of set-aside practices (2014–2023).

Geographically Weighted Regression (GWR) is used to identify the geographical variation in both environmental and anthropogenic factors influencing the use of set-aside measures. The GWR method enables the development of local models for each Polish municipality, identified by geographical coordinates (longitude and latitude). GWR facilitates the estimation of local spatial patterns regarding the various impacts on an index that aggregates the magnitude and frequency of set-aside practices from 2014 to 2023. GWR overcomes the limitations of global statistics in capturing statistically significant spatial variations in the relationships between the examined variables [66,67,68]. This approach allows for determining where and how set-aside practices were influenced by each environmental and anthropogenic factor considered.

It should be noted that global Moran’s I statistics (accompanied by expected values of Moran’s I and p-values) were estimated for each independent variable. All predictors exhibited strong positive spatial autocorrelation, indicating that the variables can show local variations in their relationships with the dependent variable (see

Table 4. Potential spatial autocorrelation of variables influencing the magnitude and frequency of set-aside practices (2014–2023).

Spatial Autocorrelation	Global Moran’s I Statistic	Expected Value of Moran’s I Statistic (Random Spatial Distribution)	p-Value	Decision on Variable Use in GWR Model: Global, or Local
Growing season	0.783055	−0.000404	→0	Local
Farm size	0.497340	−0.000404	→0	Local
Precipitation	1.092082	−0.000404	→0	Local
Environmental protection	0.407986	−0.000404	→0	Local
Consumption of mineral fertilizers	0.615944	−0.000404	→0	Local
Slope of the terrain	0.947803	−0.000404	→0	Local
Low-quality soils	0.408669	−0.000404	→0	Local
Water surface	0.299658	−0.000404	→0	Local
Social capital	0.240592	−0.000404	→0	Local

Source: Own elaboration using ArcGIS.

). Therefore, the GWR model could benefit from treating all independent variables as local, as their effects are likely to vary across space. These impacts can be expressed by the following Equation (1):

$$\begin{array}{cc}\hfill SetAsideInde{x}_i& ={\beta }_0\left(Lon{g}_i,La{t}_i\right)+{\beta }_1\left(Lon{g}_i,La{t}_i\right)GrowingSeaso{n}_i+{\beta }_2\left(Lon{g}_i,La{t}_i\right)FarmSiz{e}_i\hfill \\ & +{\beta }_3\left(Lon{g}_i,La{t}_i\right)Precipitatpo{n}_i+{\beta }_4\left(Lon{g}_i,La{t}_i\right)EnvironmentalProtectio{n}_i\hfill \\ & +{\beta }_5\left(Lon{g}_i,La{t}_i\right)Fertiliser{s}_i+{\beta }_6\left(Lon{g}_i,La{t}_i\right)TerrainSlop{e}_i\hfill \\ & +{\beta }_7\left(Lon{g}_i,La{t}_i\right)LowQualitySoil{s}_i+{\beta }_8\left(Lon{g}_i,La{t}_i\right)WaterSurfac{e}_i\hfill \\ & +{\beta }_9\left(Lon{g}_i,La{t}_i\right)SocialCapita{l}_i+{ϵ}_i\hfill \end{array}$$

(1)

where Long_i and Lat_i represent the geographical coordinates of each i-th municipality, β denotes the coefficients, and ϵ_i is the error term at location i, capturing any unexplained variation.

4. Results and Discussion

We have confirmed that rotational set-aside practices vary across Polish municipalities (see Figure 2). Generally, the western parts of Poland show the lowest values in the set-aside index, which reflects the magnitude and frequency of rotational set-aside practices from 2014 to 2023. However, the spatial variability of this phenomenon is considerably more complex, warranting further in-depth exploration and discussion.

Interestingly, both positive and negative impacts of the length of the growing season on the practice of set-aside are observed in areas with a medium-length vegetation period in Poland (see Figure 3). In line with the stated hypothesis—namely, that a shorter vegetation period correlates with a higher willingness among farmers to adopt set-aside practices [38]—a negative impact is evident in a region stretching from the southwest to the northeast of Central Poland, predominantly in the Wielkopolskie, Łódzkie, and Mazowieckie regions. This area encompasses territories with varying lengths of the growing season. Conversely, in areas with a relatively shorter growing season, a positive impact is observed, particularly in the southern part of Mazowieckie and the eastern territories of Podkarpackie. In these areas, set-aside practices are not perceived as an effective tool to address the challenges arising from the shorter vegetation period.

In the regions of Podkarpackie, Małopolskie, and Świętokrzyskie, a significant negative impact of farm size on the implementation of set-aside practices has been identified (see Figure 4). This aligns with the tendency of larger farms to prioritize profitability and economic efficiency, leading them to avoid excluding any portion of their arable land from cultivation [46]. The benefits and regulations within the European CAP do not sufficiently incentivize the owners of large farms to adopt set-aside as a mechanism for agricultural land protection and reclamation.

From the perspective of precipitation’s impact on the magnitude and frequency of set-aside practices, two regions in Poland are noteworthy (see Figure 5). The southwestern part of the Zachodniopomorskie region is characterized by relatively low precipitation and a high application of set-aside practices. On the contrary, the Podkarpackie region experiences relatively high precipitation alongside significant set-aside implementation. However, both areas exhibit a negative relationship between precipitation (the predictor) and the inclination to implement set-aside (the response variable): the lower the precipitation, the greater the willingness of farmers to adopt rotational set-aside practices. This aligns with findings by Zúñiga et al. [36], which suggest that set-aside is used to mitigate drought risks, even in areas not solely defined by low precipitation. Furthermore, the relationship between precipitation and set-aside in the Podkarpackie region underscores that this area faces technological limitations, making rotational set-aside one of the affordable solutions for addressing water shortages and limited fertilizer application, as discussed below.

Contrary to the hypothesis based on findings by Eskandari-Damaneh et al. [32], a negative relationship between the proportion of protected areas and the implementation of set-aside practices is observed in many Polish regions (see Figure 6). Greater environmental protection correlates with reduced availability of arable land, leading to a lower inclination among farmers to allocate land for rotational set-aside. Ecological pressures motivate farmers to use unprotected arable lands more intensively. Set-aside practices are not perceived as a practical agricultural contribution to environmental protection, which is not a primary priority for many farmers. This suggests that the introduction of environmental protection measures does not necessarily foster pro-ecological behaviors among farmers affected by such regulations. This trend is evident both in areas with a high share of protected land (such as the surroundings of the Bory Tucholskie National Park on the Kujawsko-Pomorskie and Pomorskie border, and in the Podkarpackie region) and in areas with a low share of protected land (e.g., the Łódzkie region). This indicates that the implementation of any form of environmental protection must be complemented by educational initiatives and subsidies, or other incentives aimed at farmers.

The concentration of farms that do not use mineral fertilizers (see Figure 7) is evident in the Podkarpackie region. In this particular area, there is a marked trend that aligns with the hypothesis stated: the smaller the farm and the lower the use of mineral fertilizers, the greater the acceptance of set-aside practices [17,42,51]. Set-aside is the primary agricultural approach considered in this region, particularly among the smallest farms with limited use of mineral fertilizers. A similar negative relationship is observed in the northern part of the Łódzkie region, characterized by relatively high consumption of mineral fertilizers. Conversely, a positive correlation between the use of mineral fertilizers and set-aside practices is observed in the area extending from the southern part of the Mazowieckie region, through Świętokrzyskie, up to the northern parts of Podkarpackie. In this zone, the use of mineral fertilizers is limited, and low-quality soils dominate the arable land. To sustain agriculture, a combined application of mineral fertilizers, and set-aside practices is necessary. A similar positive correlation is evident in the north-central part of the Kujawsko-Pomorskie region. This particular area, known as Pojezierze Brodnickie, is characterized by relatively high use of mineral fertilizers (see Figure 7). The glacial landscape, with significant elevation differences, makes agriculture challenging. Therefore, both fertilizing and set-aside practices are required simultaneously to increase soil productivity and, consequently, enhance agricultural efficiency.

The hypothesized positive relationship between the average slope of the terrain and the magnitude and frequency of set-aside practices [31,41] was not supported for mountainous areas in southern Poland, where elevation differences are the highest among Polish municipalities (see Figure 8). This outcome is due to the fact that the average slope was calculated for all terrains within municipalities, rather than specifically for arable land, which limits our investigation. In mountainous areas, the steepest slopes are generally excluded from agricultural activities, making rotational set-aside impractical. In these regions, as the average slope decreases, agricultural activities become feasible, and set-aside can be practiced, particularly in mountainous areas with low-quality soils (see Figure 8).

The areas in the southeast part of the Podkarpackie region and the north part of Warmińsko-Mazurskie exhibit a negative relationship between the share of low-quality soils and the implementation of set-aside practices (see Figure 9). Regardless of the proportion of low-quality soils, better-quality soils are more likely to be protected, as farmers show a greater willingness to preserve them. Set-aside practices are among the tools used to protect high-quality soils. In contrast, farmers tend to exploit arable land with lower-quality soils more intensively. Consequently, the hypothesis suggesting a positive relationship between the share of low-quality soils and farmers’ willingness to adopt rotational set-aside practices [4,10,19,31,33,41] has been rejected. However, soil quality is not the only factor that should be considered. We strongly recommend that future studies also examine soils from the perspective of their permeability [22,35].

A significant impact of water surface rate on the dependent variable was observed primarily in the bordering area between the Łódzkie and Mazowieckie regions, in the Podkarpackie region, and in the Żuławy area, located at the mouth of the Vistula River in the northern part of the Pomorskie region (see Figure 10). Additionally, the hypothesis of a positive impact of the water surface on farmers’ willingness to implement set-aside practices was rejected. Therefore, a higher share of water surface within a municipality correlates with reduced arable land availability and a lower inclination among farmers to allocate arable land for set-aside. It has been argued that an increase in set-aside practices is expected primarily in the steepest areas, where there is a high demand for water protection and, consequently, a need to limit the use of mineral fertilizers [31,41]. However, the previously mentioned Żuławy area is entirely flat, and there is no direct need to justify an increase in set-aside based on these arguments.

Social capital was identified as the factor with the most limited potential to predict the magnitude and frequency of set-aside practices from 2014 to 2023. Interestingly, contrary to the stated hypothesis [20,39], higher social capital correlates with a lower willingness to adopt set-aside practices. This relationship was identified in Śląsk Cieszyński in the southern part of the Śląskie region (see Figure 11). The first area comprises mountainous municipalities with economies predominantly focused on tourism, where social capital, measured by the number of NGOs per 1,000 inhabitants, is relatively low. Although social capital in Śląsk Cieszyński is relatively weak [69,70], it appears stronger in areas focused on tourism development rather than agriculture, which—due to environmental and physiographic factors—is limited or even unfeasible. Thus, the negative impact of social capital on the implementation of set-aside practices may be only apparent.

5. Conclusions

The analysis of rotational set-aside practices in Poland reveals a complex spatial variation influenced by multiple environmental and anthropogenic factors. The western regions of Poland show the lowest set-aside index values, suggesting a limited adoption of these practices, possibly due to agricultural intensification.

In Mazowieckie, the relationship between the growing season and set-aside adoption is complex, with areas of both relatively short and long vegetation periods exhibiting varying responses to set-aside. Regions such as Małopolskie, Mazowieckie, Lubelskie, Podkarpackie, and Świętokrzyskie exhibit a strong inverse relationship between farm size and set-aside adoption, indicating a trend where smaller farms, less focused on economic efficiency and using limited quantities of mineral fertilizers, are more inclined towards land conservation practices. At the same time, larger farms avoid a set-aside due to economic priorities. However, the predominance of smaller farms in regions such as Małopolskie, Podkarpackie, and Świętokrzyskie should be mentioned.

In Podkarpackie, a negative relationship between precipitation and set-aside adoption is observed, with lower precipitation areas more likely to implement set-aside as a solution to water scarcity. Regardless of the region, the more challenging the environmental characteristics from the perspective of agriculture, the stronger the tendency to combine set-aside with fertilization practices. In some parts of Podkarpackie and Warmińsko-Mazurskie regions, where poor soil quality and a high need for fertilizers prevail, set-aside practices are more likely to be combined with fertilization efforts to sustain agricultural productivity.

Protected areas and social capital have unexpected influences on set-aside use. Rather than encouraging conservation, environmental protection stimulates a reduction in set-aside adoption, as the exclusion of arable land causes a more intensive use of unprotected areas.

This multi-dimensional analysis highlights the need for tailored, region-specific policies—both European and national—that consider local agricultural, environmental, and socio-economic contexts. A review of the EU CAP framework is strongly recommended, with an emphasis on geographical context and local conditions in EU and national agricultural policymaking. The main limitation of the study arises from the challenge of including some anthropogenic factors, due to missing data for quantitative measures or the qualitative nature of other factors. Therefore, we recommend qualitative studies to explore the impact of non-measurable factors on farmers’ willingness to apply set-aside practices and to gain a deeper understanding of the processes and mechanisms shaping the already identified quantitative relationships.