The Potential Diversity of Agricultural Biomass in the Context of the Organization of Agricultural Production and Circular Agriculture in Poland

Abstract

Agriculture is one of the key sectors of the economy, but it also generates many residues and waste that are only partially used (as, for example, feed, litter, and fertilizer). The resulting residues and waste can be valuable components for other sectors of the economy (e.g., energy), contributing to the implementation of a circular economy. The main aim of the research is to assess the diversity of the biomass potential from agricultural residues in the context of the level of organization of agricultural production and circular agriculture in Poland at the local level (314 counties). The level of organization of agricultural production was determined using the synthetic measure based on four variables (average farm size, number of tractors per farm, share of farms producing for the market, and the number of AWU per 100 ha of UAA). The potential of agricultural biomass was estimated on the basis of existing surpluses of straw, hay, energy crops grown on marginal lands, and residues from orchard maintenance. The data came from the General Agricultural Census conducted by the Polish Statistical Office in 2020. The conducted research showed that over 75% of counties are characterized by a high and medium level of organization of agricultural production. However, unused biomass resources from agricultural production residues are common (2/3 of counties are characterized by high and medium potential). There is a positive relationship between the level of biomass potential from agricultural residues and the level of organization of agricultural production at the local level in Poland, but the strength of this relationship is weak.

1. Introduction

Currently, due to the existing scarcity of resources, global climate change and environmental degradation, as well as the growing demand for food, the circular economy is a promising strategy to support sustainable, restorative, and regenerative agriculture [1]. The basis for the functioning of the circular economy are sustainable practices, which include: preventing waste, direct use of by-products, and the use of renewable energy sources [2]. The circular economy is based on maximizing the value of resources indefinitely, which involves the maximum use of waste [3]. Therefore, switching to a circular system, in which the agricultural production chain changes from a linear one to a more closed-loop system with minimal unnecessary losses, could be the answer to a number of global challenges [4,5].

Nowadays, one of the main problems in the agricultural sector and agri-food industry are side products, which are considered waste [6,7]. Residues and waste are most often sent for disposal. This approach makes it impossible to obtain economic value from waste. The implementation of a circular economy may slow down this process because, according to its assumptions, waste is used in other processes, thus preventing the loss of their economic value [6]. Waste generated in agriculture, due to its valuable ingredients, can become a raw material for other industries, preventing waste and contributing to the development of a circular economy, which may also have a positive impact on the environment [8].

The problem of agricultural waste may deepen further due to population growth, which will require the agri-food industry to increase production, which will consequently lead to more waste being generated [8]. The increase in food production in recent decades has resulted in high costs for the environment [9]. Meeting the growing demand for agricultural products depends on chemical fertilizers, pesticides and mechanization, which poses a risk of environmental degradation and reduced genetic diversity [10]. Moreover, agriculture is one of the sectors that contributes largely to the planet’s greenhouse emissions. Therefore, circular economy practices can reduce the pressures of agriculture on the environment [11].

At the same time, agriculture is one of the priority sectors in the implementation of the circular economy, due to the raw material that is organic waste. Although a significant part of biomass from agricultural waste is already used to produce biomaterials and chemical compounds, the valorization of this biomass for the production of bioenergy and biofuels is becoming more and more important [12,13]. It should be emphasized that a circular economy can contribute to improving the economic performance of agricultural activities, while minimizing environmental impacts by reducing resource inputs and waste generation [14,15].

Research regarding the use of biomass is necessary not only for the efficient use of available resources, but also for achieving the goals of energy self-sufficiency and reducing greenhouse gas emissions [16]. Due to the need to maintain food security, research should focus exclusively on the use of production waste and organic waste to maximize the closed production cycle and obtain clean energy and fertilizers with zero environmental impact [17]. Lovrak et al. [18] emphasize that the development of renewable energy based on biomass is associated with the need to assess the potential of the biomass that is available and at the same time does not compete with other purposes. Moreover, the authors point out the importance of spatial analyses in this area. Díaz et al. [16] also point out the need to conduct regional spatial research. The specificity of different regions may itself determine the quantity and quality of biomass. For future prospects, it is important to adapt to the specificity of the agricultural context in different regions, both in terms of quantity and quality, as well as the classification of biomass from agricultural waste [19,20]. It may be more effective to design different circular economy modes according to the local characteristics of different regions [21]. According to Koppelmäki et al. [22], a more circular food system offers significant potential to produce bioenergy from biomass without competition for food production, which means adapting agricultural systems to locally and regionally available natural resources. Highlighting the importance of using biomass in a circular economy, Longo et al. [23] indicate the need for further multidisciplinary research. This is due to the connection of the biomass supply chain with various sectors of the economy, such as agriculture, forestry, energy, and waste management.

In order to fill the research gap related to the multidisciplinary approach to the regional and local specificity of the potential of agricultural biomass, the main aim of the research was to assess the diversity of the biomass potential from agricultural residues in the context of the level of organizing agricultural production and circular agriculture in Poland. To achieve the goal, two research questions were formulated:

Q1. What local differences can be identified in Poland in terms of the possibility of transition to circular agriculture?

Q2. What is the potential of biomass from agricultural residues (in terms of quantity and type) in Poland at the local level?

The article is structured as follows: Section 2 contains the study context. Section 3 presents the materials and methods. Section 4 describes results of the conducted research. Section 5 contains a discussion of the results. Section 6 presents the conclusions of the study.

2. Study Context

2.1. Theoretical Background

An alternative to the inefficient and environmentally unsustainable linear economy model is to use a circular economy approach to halt the growing trend of raw material consumption and decouple economic growth from raw material consumption. Circular agriculture is a concept and practice relating to the eco-environment and resource restoration. It is a sustainable strategy to address environmental problems resulting from agriculture. However, it is difficult to clearly define circular agriculture. It includes climate resilience, improving soil health, improving plant and animal production, healthy nutrient cycling, and environmental protection [24,25,26]. Circular agriculture therefore includes social, economic and ecological benefits for the environment, and comprehensive management, and its essence is to promote the use of agricultural resources in a closed loop [14]. In this approach, the development of circular agriculture is essential in today’s sustainable environments [27].

As awareness has increased, there has been a stronger focus on developing a circular economy model, focusing on waste management to bring some benefits to the agricultural sector. Agricultural biomass is a valuable resource that enables limitation of the use of primary raw materials extracted from nature. The use of biomass can be used to generate electricity, reduce agricultural waste, and reduce costs. Implementing cleaner technologies, using renewable energies and transforming a linear economy into a circular economy can increase competitiveness and create jobs, incomes, and innovation in agriculture [11,28,29,30].

Fernando et al. [31] presented a waste-to-energy supply chain based on biomass. The assumptions of the circular economy have contributed to the need to explore emerging opportunities for clean energy production in agriculture, instead of focusing solely on fertilizers and soil improvers. Agriculture produces a lot of waste, and raw materials can be obtained at lower costs. Therefore, clean energy can be obtained from landfilled agricultural waste, helping to protect the environment and strategically generate income. From a commercial point of view, a waste-to-energy supply chain can increase the potential of the circular economy in the agricultural sector and can also help solve problems such as deforestation, destruction of ecosystems, depopulation, etc.

In agriculture, the circular economy covers a strategy that meets the dual goal of improving the economic performance of agricultural activities while minimizing environmental impact by reducing resource inputs and waste generation. Therefore, the circular economy in agriculture is an economic model that respects the environment, enables the creation of new business and employment opportunities, and at the same time has a beneficial impact on the well-being of society. This is leading to the increasing use of circular models in agricultural practices [15].

It is worth emphasizing that according to Batlles-dela Fuente et al. [32] the circular economy framework has not yet been fully adapted to the field of agriculture. Furthermore, Silvestri et al. [33] and Velasco-Muñoz et al. [1] confirm that although there is extensive literature describing circular economy indicators, there is no comprehensive framework for measuring circularity in the agri-food sector.

Silvius et al. [34] indicate five principles of circular agriculture: securing the health of agroecosystems (ecosystem stocks must not be used beyond their regenerative capacity), avoiding the waste of essential resources (materials can never be fully recycled and production processes inevitably create pollution), prioritizing the use of natural resources for basic human needs (biomass should be used for essential needs first), recycling by-products of the agroecosystem (food production involves residual streams such as manure and crop residues, which need to be reused in the food system at maximum utility), minimizing and avoiding the use of energy, and using renewable energy sources (energy use should be minimized in addition to transitioning to renewables).

Among the aspects of circular agriculture, Trendov [35] mentions: farmers’ socio-economic development, reduction in the quantity of inputs, recycling and reprocessing of agricultural inputs, and ensuring biodiversity and environmental protection. In agriculture, circularity should be supported by increasing productivity while effectively using available natural resources, including increased use of biomass raw materials. Well-developed and integrated agricultural systems are of great importance, as they allow for the reduction in external inputs such as fertilizers, energy, and plant protection products. It is easier for well-organized and developed farms to move towards circular agriculture.

In addition, according to Arru et al. [36], increasing the value of agricultural production increases the circularity provided by the agricultural sector. Therefore, the increase in the level of circularity of the economy takes place primarily through the development of agriculture due to the relatively high flexibility of this sector. Agriculture’s ability to support circularity stems from the sector’s tendency towards practices based on the regeneration of natural resources and the reuse of waste materials. Similarly, in the research of Matysik-Pejas et al. [37], areas characterized by a higher level of agricultural development are also characterized by a higher degree of advancement in the implementation of the circular economy concept. The increase in agricultural productivity should cover not only the increase in demand for food, but also for biomaterials, energy, and fuels [13]. The use of intensive, high-yield agricultural systems helps meet the goals of long-term stable food supplies and waste management. The priority areas of action are waste management and waste prevention [38].

To move towards circular agriculture, new business models based on the valorization of agricultural waste are needed. Agricultural waste resources are large and heterogeneous but the quality of their raw materials varies, can deteriorate quickly, and seasonality causes quantity and quality to change over time. The condition for the successful use of agricultural waste is to ensure the availability of local resources, sufficient space, and effective infrastructure. Public awareness of the necessary changes is also supporting business development, particularly because products from waste can be produced locally and use nature-based functions [39]. What is more, according to Duque-Acevedo et al. [40], the alternative of managing waste biomass independently is profitable. This opens up a lot of opportunities for local development. However, it is necessary to promote the creation of small transformation plants at the local level and support non-profit investments that help achieve environmental goals consistent with the assumptions of the circular economy [41,42].

The use of biomass for energy purposes is still largely dependent on energy crops. However, there are also visible changes towards the processing of agricultural waste, which reduces the pressure on the environment. It should be emphasized that this waste can be used both directly on the farm and in other rural areas. It is also a valuable resource that may reduce the discrepancy between biomass production and its potential consumption in the future [43,44]. The wide local availability of this raw material results in lower overall production costs, creating an important bio-resource enabling the delivery of material products and energy in a circular economy [45,46]. For biomass-based power systems, a consistent local supply is important to ensure an uninterrupted supply of electricity to the consumer [47]. Schipfer et al. [48] also emphasize the locality of biomass and its importance for the circular economy. The authors consider appropriate raw materials, including agricultural residues, as the basis of the future circular economy. As indicated by Lange et al. [49], farmers can make a significant contribution to the circular economy by improving resource efficiency. Furthermore, Babu et al. [50] emphasize that effective agricultural waste management can ensure energy security while reducing environmental pollution. This is important because significant, underutilized resources of waste-derived biomass are quite common. It should be added that the development of circular agriculture requires full integration of production, education, and research [51].

2.2. Characteristics of Agriculture and the State of Use of Agricultural Residues and Waste in Poland

Polish agriculture is regionally diversified. The main reason for this condition is differences in agro-climatic conditions, such as soil quality, terrain, water conditions, and climatic conditions. However, it should be emphasized that Poland ranks third in Europe in terms of the share of agricultural area in the entire country. A large area of agricultural land allows for less intensive use of land and the use of production methods that are more environmentally friendly. However, Polish agriculture is generally characterized by significant fragmentation [52]. The average size of a farm is 12.7 ha. However, the size of farms varies regionally; larger farms are located in the northern and western parts of the country (Zachodniopomorskie Voivodeship—34.9 ha; Warmińsko-Mazurskie Voivodeship—28.2 ha; Lubuskie Voivodeship—24.2 ha) and smaller farms are located in the southern and eastern parts of the country (Małopolskie Voivodeship—5.3 ha; Podkarpackie Voivodeship—6.0 ha; Świętokrzyskie Voivodeship—7.1 ha) [53].

As a result of the fragmentation of farms, relatively high employment is observed in Polish agriculture. However, due to the dependence of agricultural production on weather conditions, during periods of intense work there is a need to additionally employ seasonal workers [52]. On average in Poland, the labor input of users and their family members on individual farms is at the level of 9.3 AWU/100 ha of UAA. These expenditures also vary regionally; smaller labor inputs occur in northern and western Poland (Zachodniopomorskie Voivodeship—3.2 AWU/100 ha of UAA; Lubuskie Voivodeship—3.9 AWU/100 ha of UAA; Warmińsko-Mazurskie Voivodeship—4.4 AWU/100 ha of UAA), while they are much higher in southern and eastern Poland (Małopolskie Voivodeship—23.0 AWU/100 ha of UAA; Podkarpackie Voivodeship—16.7 AWU/100 ha of UAA; Świętokrzyskie Voivodeship—16.0 AWU/100 ha of UAA) [53].

The diversity of soil quality and the size of farms means that Polish agriculture is also regionally differentiated in terms of intensity. Better results in terms of yields are obtained in the northern and western parts of the country, where there are a large number of commercial farms with intensive production. However, production results are much less favorable in the southern and eastern parts of the country, where there are a large number of small farms using labor-intensive and extensive production methods. As a result, the manufactured products are largely intended for own needs and direct sales [52]. The highest share of farms in which the final production is intended for sale occurs in the northern and western parts of the country (in the Kujawsko-Pomorskie Voivodeship—86.9%; Wielkopolskie Voivodeship—85.8%; and Podlaskie Voivodeship—81.5%), while a much smaller share of such farms occurs in the south of the country (in the Podkarpackie Voivodeship—39.9%; Lesser Poland—44.8%; and Silesia—58.1% [53].

The intensity of production is also reflected in the involvement of capital in production, which involves the mechanization of work. Mechanization, expressed in the number of tractors per farm, also varies in Poland [52]. There are more tractors per farm in northern and western Poland (Kujawsko-Pomorskie Voivodeship—1.4 tractors/farm; Podlaskie Voivodeship1.4 tractors/farm; Wielkopolskie Voivodeship—1.3 tractors/farm), while there are fewer in southern part of the country (Podkarpackie Voivodeship—0.8 tractors/farm; Małopolskie Voivodeship—0.8 tractors/farm) [53].

Agricultural production requires significant energy inputs, mainly in the form of electricity and fuels. The share in direct energy consumption in the Polish agricultural sector in 2022 was 4.3% [54]. The prospect of a progressive increase in prices resulting from the scarcity of natural resources and the global energy deficit makes it necessary to look for alternative energy sources. The agricultural sector has significant energy potential that is yet untapped. The use of the agricultural sector to produce energy may contribute to reducing expenditure on agricultural production and environmental protection [55].

Biomass is widely used to produce renewable energy in Poland. The highest share in the total production of renewable energy in 2020 was held by solid biofuels, whose share was 71.6%. The second largest source of biomass used for energy purposes were liquid biofuels, whose share was 7.8%. Biogas came in third with a share of 2.6%. Moreover, renewable municipal waste is used to a small extent for energy purposes, the share of which in total production was 1.1% [56].

The presented structure of renewable sources in Poland indicates that in the field of biomass, special-purpose crops are used (e.g., forests—solid biofuels; cereals—liquid biofuels), while waste from agriculture is used to a small extent (e.g., natural fertilizers for biogas production, straw for heat production). As Malec [57] emphasizes, the most desirable action is the use of all raw materials from by-production and waste. Moreover, according to the author, there is a reserve in Poland that can be used for energy purposes (especially in the field of degraded, destroyed or other low-quality land). Therefore, it is necessary to take action to fully utilize the potential of biomass that has not yet been used and constitutes production surpluses of particularly low quality.

It should be emphasized that the use of waste for energy purposes is in line with the latest Directive (EU) 2023/2413 of the European Parliament and of the Council of 18 October 2023 on renewable energy sources [58]. According to the provisions of the directive, Member States’ support systems for bioenergy should focus on raw materials for which there is little market competition with the raw material sectors and whose acquisition is considered beneficial for both the climate and biodiversity. The increasing importance of biomass may be influenced by increased awareness of the possibilities of full use of this renewable energy source, e.g., the use of surplus straw or the use of low-quality land for the cultivation of energy plants [57].

3. Materials and Methods

To achieve the research aim, the analyses were conducted at the local level for 314 counties in Poland and all land counties were included. Owing to the research being agricultural, city counties were excluded.

The assessment of agricultural diversification is usually made taking into account the resources of production factors, inputs, and costs, as well as the production volume and income. In the classical approach, the main factors of production include land (the embodiment of the forces of nature), labor (labor force) and capital (equipment with fixed and current assets) [37,59]. Therefore, in order to determine the level of organized agriculture production in Poland, four indicators were used: average size of a farm (in ha), number of tractors per 1 farm (piece), share of farms in which marginal production is intended for the market (%) and the number of full-time employees per 100 ha of agricultural land (AWU/100 ha of UAA). The data came from the General Agricultural Census conducted by the Central Statistical Office in 2020 [60]. The statistical data that were downloaded from the database and used during the research concerned: the number of farms, the area used by farms, the number of tractors, the number of farms whose production is intended for sale, the number of full-time employees in agriculture, and the area of agricultural land.

Table 1. Variables of the level of organized agriculture production—the summary statistics.

Specification	Average Farm Size	Number of Tractors per Farm	Share of Farms with Final Production for Sale	Number of Full-Time Employees per 100 ha of UAA
Total number of counties	314
Minimum	3.92	0.49	12.88	2.17
Maximum	46.26	1.80	95.47	32.94
Range	42.34	1.31	82.59	30.78
Average	14.47	1.12	70.37	9.97
Median	13.96	1.09	74.54	8.45
Standard deviation	7.57	0.27	17.75	5.94
Sample variance	57.26	0.07	315.10	35.31

Source: own calculation based on [60].

presents summary statistics for each variable.

A necessary condition for the construction of a synthetic measure is the normalization of the adopted variables. The main goal of this procedure is to achieve mutual comparability of variables that are expressed in different units. Moreover, the purpose of normalization is to eliminate negative values from calculations and to maintain a stable level of variability [61]. Selected indicators were normalized using the unitarization process with the following formulas [62]:

$$\mathrm{for} \mathrm{stimulants}: z_{ij}=\frac{x_{ij}-\min \{x_{ij}\}}{\underset{i}{\max }\{x_{ij}\}-\underset{i}{\min }\{x_{ij}\}},$$

(1)

$$\mathrm{for} \mathrm{destimulants}: z_{ij}=\frac{\underset{i}{\max }\{x_{ij}\}-x_{ij}}{\underset{i}{\max }\{x_{ij}\}-\underset{i}{\min }\{x_{ij}\}},$$

(2)

where z_ij—value of the normalized j-th variable for the i-th spatial unit; and x_ij—value of the j-th variable for the i-th spatial unit.

As a result of applying the unitization formula, the variables show the same range of variability. Therefore, unitization allows maintenance of the differentiated variance of features and proportions between the normalized and original values of the variable. In the case of selected indicators, the number of full-time workers per 100 ha of agricultural land was treated as a destimulant (negatively correlated with the level of organizing agricultural production), while the remaining indicators were considered stimulants (positively correlated with the level of agricultural production organization) [61]. The synthetic measure method was used to assess the level of agricultural diversification. A patternless method was used to determine the values of synthetic indicators, consisting in averaging the normalized feature values:

$$q_i=\frac{{\displaystyle \sum _{j=1}^m{z_i}_j}}{m},(i=1,2,\dots ,n);\mathrm{t}\mathrm{h}\mathrm{e} \mathrm{v}\mathrm{a}\mathrm{l}\mathrm{u}\mathrm{e} \mathrm{o}\mathrm{f} {\mathrm{q}}_{\mathrm{i}} \mathrm{b}\mathrm{e}\mathrm{l}\mathrm{o}\mathrm{n}\mathrm{g}\mathrm{s} \mathrm{t}\mathrm{o} \mathrm{t}\mathrm{h}\mathrm{e} \mathrm{r}\mathrm{a}\mathrm{n}\mathrm{g}\mathrm{e} (0,1).$$

(3)

where q_i—value of the synthetic meter; z_ij—value of the normalized j-th variable for the i-th spatial unit; and m—number of indicators included.

Based on the value of the synthetic indicator (q_i), arithmetic mean (q_a), and standard deviation (q_s), the studied counties were divided into three classes representing different levels of agricultural organization: class I—high level, q_i < (q_a − 0.5 q_s); class II—medium level, (q_a − 0.5 q_s) ≤ q_i ≤ (q_a + 0.5 q_s); and class III—low level, q_i > (q_a + 0.5 q_s) [63].

Biomass, which is a by-product of plant and animal production, is very important for maintaining the continuity of agricultural activity and is, as it were, an element of the closed loop. Traditionally, biomass from cereal production in the form of straw is used for bedding and feed purposes (for farm animals) and to increase the organic mass of soil (as a natural fertilizer). Biomass created from meadows and pastures in the form of hay is used for feed purposes (for farm animals). Biomass resulting from animal production (manure, slurry) is used to increase the organic mass of soil (as a natural fertilizer). For this reason, the research used formulas that take into account only surplus biomass that is not used in agricultural activities for energy purposes. Alternatively, surpluses can be used, e.g., for energy purposes.

The estimated potential of biomass from agricultural production residues consists of waste from plant production, i.e., surplus of straw, hay, purposely cultivated energy crops, and residues from orchard maintenance. During the study, by-products from animal production (natural fertilizers) were also analyzed, but due to their wide use in plant production, no surplus of them that could be used for other purposes was identified. The data on the basis of which the technical potential of biomass from residues and waste was estimated came from the 2020 General Agricultural Census conducted by the Central Statistical Office in Poland [60]. The research used statistical data regarding:

-

Area of cereal crops (wheat, rye, barley, oats, triticale, cereal mixtures, corn, rapeseed, and turnip rape);

-

Yield of cereals (wheat, rye, barley, oats, triticale, cereal mixtures, corn, rapeseed, and turnip rape) and meadows and pastures (hay);

-

Animal population (cattle, pigs, sheep, horses, goats);

-

Land use (area of meadows and pastures, area of orchards, area of fallow land).

The technical potential for straw surpluses was identified on the basis of the difference between its production (cereal area and straw yield) and its use in animal production (feed and bedding for animals) and plant production (organic matter for arable soils), taking into account its energy value and the efficiency of devices for its conversion into energy [64]:

$$P={\sum }_{i=1}^n\mathrm{N}\times 13\times 80\mathrm{\%}$$

(4)

where P—potential of straw; N—surplus of straw in a given area (difference between production and consumption of straw in agriculture); 13 GJ/t—energy value of straw; and 80%—efficiency of equipment converting raw material into usable energy.

The technical potential for surplus hay was identified on the basis of the difference between its production (area of meadows and pastures and hay yield) and the demand for animal production (animal feed), taking into account its energy value and the efficiency of equipment for its conversion into energy [65]:

P_ts = A × Y × w_ws × 13.4 × 80%

(5)

where P_ts—hay potential; A—area of permanent grasslands; Y—hay yield from meadows and pastures (4 t/ha); w_ws—coefficient of use for energy purposes (7.5% of meadows and pastures); 13.4 GJ/t—energy value of hay; and 80%—device efficiency.

The technical potential from energy crops was determined based on the area of fallow land and the average yield of energy crops, taking into account their energy value and the efficiency of devices converting biomass into energy [66]:

P_re = A_d × Y_re (t/ha) × 18 (GJ/t) × 80%

(6)

where P_re—potential of perennial plants intended for energy purposes; A_d—area of land available for the cultivation of energy crops (50% of fallow land); Y_re—average yield of selected energy crops (8 t ha/ha/year); 18 GJ/t—energy value of willow; and 80%—efficiency of devices for burning biomass.

The technical potential of biomass from orchard maintenance was estimated based on the area of orchards, wood yield during maintenance, energy value of wood, and the efficiency of devices converting biomass into energy [67]:

Z_ds = A × u_d × w_e × 80% (GJ/rok)

(7)

where Z_ds—energy potential of waste wood resources from orchards (GJ); A—orchard area (ha); u_d—yield of waste wood (0.35 t/ha) from 1 ha of orchards; w_e—energy value of wood; and 80%—equipment efficiency.

The results obtained using the presented formulas allowed for the assessment of the existing potential of biomass from residues and waste in the studied counties of Poland (

Table 2. Variables of the level of biomass potential from agricultural residues and waste—the summary statistics.

Specification	Straw Surplus	Surplus Hay	Growing Energy Crops	Residues from Orchard Maintenance	Total
Total number of counties	314
Minimum	−1.52	0.07	0.00	0.00	0.47
Maximum	96.47	5.85	5.58	3.86	98.12
Range	97.99	5.79	5.58	3.86	97.64
Average	20.93	0.76	0.74	0.07	22.51
Median	17.86	0.55	0.52	0.02	19.39
Standard deviation	17.53	0.69	0.69	0.27	17.39
Sample variance	307.45	0.48	0.48	0.07	302.56

Source: Own study based on [60].

presents summary statistics for each variable). With regard to the comparison of counties, the determined potential of agricultural biomass was calculated per 100 ha of agricultural land.

The counties were divided into three classes with different levels of biomass potential (B_p), based on the arithmetic mean (B_a) and standard deviation (B_s): class I—high level, B_p < (B_a − 0.5 B_s); class II—medium level, (B_a − 0.5 B_s) ≤ B_p ≤ (B_a + 0.5 B_s); class III—low level, B_p > (B_a + 0.5 B_s) [63].

The determined levels of agricultural organization and biomass potential from residues and waste resulting from agricultural production are summarized in a matrix (Figure 1).

As a result of the matrix comparison, the studied counties were divided into nine groups with different levels of agricultural organization and the potential of biomass from agricultural production residues and waste.

4. Results

Based on the indicators that were taken into account regarding the organization of agriculture production, the studied counties were divided into three classes. The first class represents a high level of agricultural organization; the synthetic measure ranges from 0.62 to 0.83 with an average of 0.54. This class includes 111 counties, constituting 34.4% of all surveyed counties. The values of the included indicators in this class are significantly above the average in the case of stimulants and below the average in the case of destimulants. Counties of this class are located mainly in the northern part of the country. In the second class, characterized by an average level of agricultural organization, the synthetic index ranges from 0.46 to 0.62. The second-class counties turned out to be the most numerous, of which there are 126, constituting 40.1% of all surveyed counties. The values of the included indicators in this class are at the average level for all surveyed counties. Counties in this class are located mainly in the western and eastern parts of the country. The third class is characterized by a low level of agricultural organization; the value of the synthetic index ranges from 0.06 to 0.46. There are 77 counties in this class, which constitute 24.5% of all surveyed units. The values of the included indicators in this class are significantly below average in the case of stimulants, and in the case of destimulants they are above average. Counties of this class are located mainly in the southern part of the country.

Based on the estimated biomass potential from agricultural residues and waste, the studied counties were again divided into three classes. The first class is characterized by the highest average level of biomass potential per 100 ha of agricultural land, amounting to 103.5 toe with a general average of 55.5 toe. This class includes 75 counties, which constituted 23.9% of all surveyed units. Counties of this class are located mainly in the western and central parts of the country. The second class is characterized by an average level of biomass potential from agricultural residues and waste, amounting to 55.3 toe/100 ha of UAA. Counties in this class turned out to be the most numerous, of which there are 136, constituting 43.3% of all surveyed units. Counties of this class are located mainly in the western and south-eastern parts of the country. The third class, on the other hand, is characterized by a low level of biomass potential from agricultural residues and waste, which amounted to 20.6 toe/100 ha of UAA. This class includes 103 counties, which constitute 32.8% of all surveyed units. Counties of this class are located mainly in the eastern, southern, and partly central parts of the country.

Based on the assessment of the level of agriculture production organization and the level of biomass potential from agricultural residues and waste, the studied counties were divided into nine groups (Figure 2,

Table 3. Variation in the level of agriculture and the potential of biomass from agricultural production residues and waste in Polish counties: research results.

Diversification of the Level of Agriculture Production Organization				Diversification of Biomass Potential from Agricultural Residues and Waste (toe/100 ha of Agricultural Area)					Number of Counties in the Group
Average Farm Size	Number of Tractors per Farm	Share of Farms with Final Production for Sale	Number of Full-Time Employees per 100 ha of UAA	Straw Surplus	Surplus Hay	Growing Energy Crops	Residues from Orchard Maintenance	Total
Group I (High Agriculture/High Biomass)									40
22.0	1.4	82.2	5.4	101.7	0.8	1.0	0.0	103.6
Group II (High Agriculture/Medium Biomass)									41
22.0	1.3	79.9	5.8	56.7	1.4	1.1	0.1	59.3
Group III (High agriculture/Low biomass)									30
19.3	1.4	80.7	7.1	11.6	2.5	0.9	0.0	15.0
Group IV (Medium Agriculture/High Biomass)									26
15.7	1.0	70.7	6.5	102.3	1.1	1.7	0.1	105.2
Group V (Medium Agriculture/Medium Biomass)									63
12.5	1.1	75.7	9.5	52.1	1.5	1.9	0.1	55.7
Group VI (Medium Agriculture/Low Biomass)									37
13.1	1.1	75.4	10.0	21.6	2.2	1.6	0.4	25.8
Group VII (Low Agriculture/High Biomass)									8
7.0	0.9	59.4	13.3	94.1	1.5	3.0	0.3	98.9
Group VIII (Low Agriculture/Medium Biomass)									33
6.3	0.8	51.9	16.4	44.0	2.3	4.7	0.1	51.0
Group IX (Low Agriculture/Low Biomass)									36
6.6	0.8	42.5	18.8	12.1	4.1	3.9	0.5	20.5
Total (average for all counties)									314
14.5	1.1	70.4	10.0	51.4	1.9	2.1	0.2	55.5

Source: Own study.

). The conducted research indicates that there is a positive relationship between the level of agricultural organization and the level of biomass potential from agricultural residues and waste, but its strength is weak (0.29).

The first group is characterized by a high level of organizing agriculture production and high level of biomass potential from agricultural production. This group includes 40 Polish counties, mainly located in the central part of Poland (Kujawsko-Pomorskie Voivodeship and Wielkopolskie Voivodeship). In terms of the organization of agricultural production, the counties of this group are distinguished by the highest values in the case of stimulants and the lowest in the case of destimulants. Agriculture in this group is characterized by a large average size of farms (22 ha), a significant number of tractors per one farm (1.4 pcs./farm), and a significant share of farms with production for sale (82.2%). The lowest value among all groups is recorded in terms of the number of full-time employees (5.4 AWU/100 ha of UAA). However, in terms of the overall biomass potential, the counties of this group are characterized by the second highest result, averaging 103.6 toe/100 ha of agricultural land. Straw surpluses have the highest average potential among biomass sources (101.7 toe/100 ha of UAA). The remaining biomass sources are characterized by a much lower than the overall average biomass potential from agricultural production (hay surplus—0.8 toe/100 ha; energy crops—1.0; and residues from orchard maintenance—0.0 toe/100 ha of UAA).

The second group is characterized by a high level of organizing agriculture production and an average level of biomass potential from agricultural production. This group includes 41 counties, which are also located in the central (Kujawsko-Pomorskie Voivodeship and Wielkopolskie Voivodeship) and northern parts of the country (Zachodniopomorskie Voivodeship and Warmińsko-Mazurskie Voivodeship). Taking into account the level of agriculture production organization, counties in this group are characterized, similarly to the first group, by high values of stimulant indicators and low values of destimulant indicators. This group is distinguished by a large average farm area (22.0 ha), a large number of tractors on the farm (1.3 pcs./100 ha of UAA) and a high share of farms with final production for sale (79.9%). Moreover, this group has a low, favorable number of full-time employees (5.8 AWU/100 ha of UAA). Regarding the overall biomass potential from agricultural production, the counties of this group are characterized by a value close to the average (59.3 toe/100 ha of UAA). In the case of individual sources of biomass potential, the value of straw surpluses is slightly higher than the general average (56.7 toe/100 ha of UAA). However, in the case of other sources, the values are slightly below the average: hay surplus—1.4 toe/100 ha of UAA; cultivation of energy crops—1.1 toe/100 ha of UAA; and residues from orchard maintenance—0.1 toe/100ha of UAA.

The third group is characterized by a high level of agriculture production organization and a low level of biomass potential from agricultural production. This group includes 30 counties, which are located mainly in the north-eastern part of the country (Podlaskie Voivodeship, Warmińsko-Mauzurskie Voivodeship, and Mazowieckie Voivodeship). In the second class, the level of organization of agricultural production is distinguished by high values of indicators regarding the size of farms (19.3 ha), the number of tractors on a farm (1.4 pcs./farm), and the share of farms with final production for sale (80.7%), while having a low, favorable value in terms of the number of full-time employees (7.1 AWU/100 ha of UAA). A characteristic feature of this group is the lowest overall biomass potential from agricultural production among all groups, which is 15.0 toe/100 ha of UAA. Taking into account individual biomass sources, the potential for hay surpluses is the highest among all groups and amounts to 2.5 toe/100 ha of UAA. However, in the case of other sources of biomass potential, compared to the other groups the lowest values include: straw surplus—11.6 toe/100 ha of UAA; cultivation of energy crops—0.9 toe/100 ha of UAA; and residues from orchard maintenance—0.0 toe/100 ha of UAA.

The fourth group includes 26 counties located mainly in the southwestern part of the country (mainly Dolnośląskie Voivodeship). This group is distinguished by an average level of agricultural production organization and a high level of biomass potential from agricultural production. Regarding indicators of the level of agriculture production organization, most of their values are close to the average for all surveyed counties (average farm size—15.7 ha; number of tractors on a farm—1.0 pcs/farm; and share of farms with production for sale—70.7%). The number of full-time employees is slightly higher than the average and amounted to 6.5 AWU/100 ha of UAA. In the case of overall biomass potential, this group stands out with the highest result compared to the others. Analyzing individual sources of the total biomass potential, the highest value refers to straw surpluses (102.3 toe/100 ha of UAA) and energy plants (1.7 toe/100 ha of UAA), while lower values refer to hay surpluses (1.1 toe/100 ha of UAA) and residues from orchard maintenance (0.1 toe/100 ha of UAA).

The fifth group is the largest, as it includes as many as 63 counties in Poland, located mainly in the central and eastern part of the country (Łódzkie Voivodeship, Lubelskie Voivodeship, and Mazowickie Voivodeship). This group is characterized by an average level of agricultural production organization and an average level of biomass potential from agricultural production. In this group, the indicator values are close to the average for all surveyed counties. Analyzing the level of organization of agricultural production—farm size (12.5 ha) and number of full-time employees (9.5 AWU/100 ha of UAA) are slightly lower, while the share of farms with final production for sale (75.7%) is slightly higher than average for all counties. The number of tractors per farm (1.1 pcs/farm) is the same as the average for all counties. The overall potential of agricultural biomass is slightly higher (55.7 toe/100 ha of UAA) than the average for all surveyed counties, but among individual sources, only straw surplus is characterized by a slightly higher value (52.1 toe/100 ha of UAA). The values of potential from surplus hay (1.5 toe/100 ha of UAA), growing energy crops (1.9 toe/100 ha of UAA) and residues from orchard maintenance (0.1 toe/100 ha of UAA) are lower than the average for all counties.

The sixth group represents an average level of organizing agriculture production and a low level of biomass potential from agricultural production. This group includes 37 counties located mainly in the central part of the country (Mazowieckie Voivodeship). In terms of the level of organizing agriculture production, the total area of farms is lower than average (13.1 ha). The number of tractors on a farm is average (1.1 pcs/farm). However, the indicators of the share of farms with final production for sale (75.4%) and the number of full-time employees (10.0 AWU/100 ha of UAA) are higher than average. Regarding the overall level of biomass potential from agricultural production, the value is much lower than the average (25.8 toe/100 ha of UAA). In terms of individual sources of biomass from agricultural production, values below the average refer surpluses of straw (21.6 toe/100 ha of UAA) and energy crops (1.6 toe/100 ha of UAA). However, values above the average refer hay surpluses (2.2 toe/100 ha of UAA) and residues from orchard maintenance (0.4 toe/100 ha of UAA).

The seventh group, characterized by a low level of organizing agriculture production and a high level of biomass potential, is the least numerous and covers only eight counties. In terms of the level of organizing agriculture production, stimulating indicators have values significantly below the average (average farm size—7.0 ha; number of tractors on a farm—0.9 pcs/farm; share of farms with production for sale—59.4%), while the destimulating indicator exceeds the average value (number of full-time employees—11.3 AWU/100 ha of UAA). Regarding the level of the overall biomass potential from agricultural production, a value significantly exceeds the average for all counties (98.9 toe/100 ha of UAA). In terms of individual biomass sources, a high value was recorded for straw surplus (94.1 toe/100 ha of UAA) and the highest value of the potential for energy crops (3.0 toe/100 ha of UAA) compared to other groups. Residues from orchard maintenance were also above average (0.3 toe/100 ha of UAA). Hay surpluses are below the average for all surveyed counties (1.5 toe/100 ha of UAA).

The eighth group is characterized by a low level of organizing agriculture production and an average level of biomass potential from agricultural production. This group includes 33 counties located mainly in the southern part of the countries (Podkarpackie, Małopolskie and Śląskie Voivodeships). In the analyzed group, in terms of the level of organization of agricultural production, the indicator values are definitely lower than the average for stimulants and definitely higher than the general average for destimulants. This group is characterized by the smallest size of farms (6.3 ha) and the number of tractors on the farm (0.8 pcs./farm) compared to the other groups. However, the number of people employed full-time (16.4 AWU/100 ha of UAA) significantly exceeds the average value for all groups. In this group, the overall biomass potential is 51.0 toe/100 ha of UAA. In the case of straw surpluses (44.0 toe/100 ha of UAA) and orchard maintenance residues (0.1 toe/100 ha of UAA), values are lower than average, while in the case of energy plants, the value is the highest among all analyzed groups (4.7 toe/100 ha of UAA).

The ninth group is characterized by a low level of organizing agriculture production and a low level of agricultural biomass potential. This group includes 36 counties located in the south-eastern part of the country (Podkarpackie Voivodeship, Małopolskie Voivodeship, Świętokrzyskie Voivodeship, and Mazowieckie Voivodeship). Regarding the level of organizing agriculture production, the values in terms of stimulants are very low, and the highest in terms of destimulants: the number of full-time employees (18.8 AWU/100 ha of UAA). Regarding the overall level of biomass, the value is the lowest compared to the other groups. However, in terms of individual sources, for surplus hay the value is highest (4.1 toe/100 ha of UAA), similarly to residues from orchard maintenance (0.5 toe/100 ha of UAA) compared to the other groups. Quite high values (above average) refer to the field of energy crops (3.9 toe/100 ha of UAA). By far the lowest agricultural biomass potential in this group concerns straw surpluses.

Figure 3 shows the results of the analyses from a regional perspective. Due to the potential of agricultural biomass, five regions are distinguished: Lower Silesia, Kuyavian-Pomeranian Voivodeship, Opole Voivodeship, Greater Poland Voivodeship and West Pomeranian Voivodeship. This means that in these regions, due to both the total volume of biomass and its efficiency per 100 ha UAA, the average values for the entire country are exceeded. These regions are located mainly in the western part of the country. The eastern side is characterized by lower values of biomass potential; in particular, lower efficiency per 100 ha of UAA. Poland is at the stage of energy transformation, which was taken into account in the national strategic document on energy policy [68]. The first goal assumes optimal use of domestic energy resources, including biomass. The document clearly states that the energy sector in Poland should use in particular biomass, which is not used in other branches of the economy. The regional approach to the analyzed specific objective is closely related to the location of raw materials. This means switching from biomass derived from energy crops to agricultural waste biomass. The western part of the country has good conditions for this, but requires the development of appropriate infrastructure. It is worth adding that, according to another strategic document related to the state’s ecological policy [69], the level of implementation of the circular economy concept in Poland is still low. The use of the existing agricultural biomass potential in Poland fits into the concept of the closed loop, contributing to reducing pressure on the environment.

In Poland, the energy consumption of biomass should increase in the near future. Currently, the main source of biomass for energy purposes are energy crops, which, however, contribute to strong competition for land between food production and energy production. Biomass produced by large, well-organized farms is also partially used [56]. The results of the presented research show that there is a potential for biomass from waste and residues from agricultural production in Poland, regardless of the level of organization of agricultural production. Including this potential would reduce the conflict and at the same time allow the implementation of the assumptions of the circular economy. This requires a lot of investment and interest from both the authorities and institutions, as well as other stakeholders. in a transitional approach, medium- and low-organized farms could be included in the energy biomass cycle, initially to a small extent, constituting an additional source. Ultimately, these farms could become the main supplier of biomass for energy purposes, and energy crops would take over the role of an additional source (Figure 4), freeing up some good land.

5. Discussion

In accordance with the aim, the article assessed the diversity of the biomass potential from agricultural residues in the context of the level of agricultural production organization and circular agriculture in Poland. It should be emphasized that the level of organization of agricultural production in Poland varies significantly, regionally and locally. The results show that 35% of the surveyed counties represent a high level of agriculture production organization and are located mainly in the northern and central parts of the country. Moreover, 40% of the surveyed counties are characterized by an average level of agricultural organization and are located in the western, central, and partly in the eastern part of the country. However, only 25% of the surveyed counties are characterized by a low level of agriculture production organization. This situation is typical for counties located in the southern part of the country. Taking into account the results of Matysik-Pejas et al. [37], Arru et al. [36], Lange et al. [49] and Aznar-Sánchez et al. [38], the development of effective agricultural production favors the circular economy. This is related to the flexibility of this sector, as well as the reuse of resources. The transition of agriculture towards circularity requires the use of new solutions, including business ones [39]. Well-organized farms conducting market activities are more inclined to adopt these types of solutions. In addition to environmental benefits, these solutions may also have economic benefits (e.g., cost reduction and efficiency improvement) [14,15]. Therefore, due to the high and medium level of agriculture production organization, covering most counties, Poland has the conditions for transition to a circular economy, including circular agriculture. With regard to the managerial implications, it is necessary to create conditions to improve the efficiency of agricultural activities, e.g., in the form of support programs at the national or regional level. In addition to farmers, the authorities—both central and local government—and other organizations supporting the improvement of agricultural efficiency should also be involved in this process. It is also necessary to coordinate activities so that they actually begin to bring the expected results.

In Poland, there is significant untapped potential for biomass from agricultural residues at the local level. In the surveyed counties, unused biomass resources from agricultural production residues are common: 67% of the surveyed units are characterized by a medium and high level of biomass potential from agricultural production residues. As Babu et al. emphasizes [50], this situation may contribute to increasing energy security and also reduce the impact on the environment. However, in agreement with Donner et al. [39], the condition for the effective use of waste and agricultural residues is to ensure the availability of local resources and sufficient space with appropriate infrastructure. In addition, there is a need to promote the creation of small biomass processing plants at the local level, as Duque-Acevedo et al. point out in their research [40]. Therefore, the managerial implication in this respect relates to the need to build plants processing agricultural waste biomass, enabling the use of biomass potential that has not been used so far. This is consistent with Malec’s results [57]. Such actions will also help to close the loop.

The results indicate that there is a positive relationship between the level of biomass potential from agricultural residues and the level of agriculture production organization at the local level in Poland, but the strength of this relationship is weak. Therefore, the hypothesis was not confirmed. As indicated by the research of Trendov [35] and Arru et al. [36], it is easier for well-developed and organized farms to transition to a circular economy. Therefore, the development of a circular economy in agriculture should be carried out by supporting productivity, taking into account the efficiency of resource use through the use of biomass. However, the conducted research shows that only about 35% of the surveyed counties are characterized by highly organized agricultural production. Therefore, in Poland, in terms of the use of agricultural production residues, it is necessary to take into account not only large, highly organized farms, but also to support other farms in improving productivity, which may turn out to be biomass suppliers at the local level. In this respect, managerial implications refer to the need to include in plans for the use of waste biomass from agriculture, not only from highly organized, large farms, but also others who may turn out to be suppliers of biomass at the local level.

The main limitation of the conducted research turned out to be the availability of public statistics data at the local level. Due to these limitations, circularity was referred to in an indirect way, through the level of organizing agricultural production. This significantly limited the possibilities of formulating and testing hypotheses. Hence, further research directions should include research that goes beyond public statistics data at the local level, taking into account aspects such as waste management on farms and energy management. It is also worth supplementing quantitative research with a qualitative assessment.

6. Conclusions

The ongoing changes in agriculture also cause evolution in its functions. In addition to the functions typical of agriculture, such as the production of raw materials and food products that determine food security, new functions appear. Currently, the topic of expanding agricultural activities to include non-agricultural functions and the use of agricultural raw materials for energy purposes is often raised. Both the level of organization of agriculture and the identified level of biomass potential from agricultural residues indicate the possibilities of developing functions related to energy production.

The conducted research shows that the greatest opportunities for the development of agriculture towards serving as a supplier of resources for energy purposes lie in the counties of the northern part of the country (Zachodniopomorskie Voivodeship, Pomorskie Voivodeship, Warmińsko-Mazurskie Voivodeship, and Kujawsko-Pomorskie Voivodeship). More than 80 surveyed counties in Poland, constituting 25.8% of all surveyed units, are characterized by a high level of agriculture production organization and a high or average level of biomass potential from agricultural residues (groups I and II). Moreover, another 89 counties in Poland, constituting 28.3% of all surveyed units, are characterized by an average level of agriculture production organization and a high or average level of agricultural biomass potential (groups IV and V). These types of units are located mainly in the western (Dolnośląskie Voivodeship and Lubuskie Voivodeship), central (Łódzkie Voivodeship) and partially eastern (Lubelskie Voivodeship) parts of Poland. Therefore, over half of the counties in Poland (54.1%) have a chance to develop additional functions in the agricultural sector in the field of energy production.

The use of agricultural residues, which under normal conditions would constitute waste and be wasted in the studied counties, may contribute to the implementation of the assumptions of a circular economy. In the field of agriculture, the use of such solutions will optimize the efficiency of natural resources and support the efficiency of waste use. Moreover, since biomass is a local resource and should be used locally, it can contribute to closing the loop in the agricultural sector. In addition, the creation of new demand in agriculture (raw materials for energy purposes) may contribute to increasing agricultural production and the use of all agricultural land, even those of marginal importance. However, on a national scale, energy production from agricultural raw materials can help meet international obligations.

The strategy for circular agriculture based on biomass should take into account various programs, plans and actions, both vertically (at the national, regional and local levels) and horizontally (including farms regardless of their size or level of organization). At the national and regional level this strategy should include institutional and financial support programs for improving the efficiency of agriculture in Poland, as well as a program and system of activities coordinating various levels in this regard; while at the local level, plans should be created for the construction of plants processing biomass from agricultural waste and plans for the management of waste biomass from agriculture.