3.1. Analysis of the Farm Economic Viability
The long-term economic viability (LTEV) indicator, as a measure of overall farm viability, showed positive values throughout the observed period. The average coefficient exceeds one across all types of farming, indicating that farms can cover the opportunity costs of production factors from their net income (
Table 2). As expected, the obtained results differ among various types of farming. The LTEV indicator is highest for field crop farms (2.91), and lowest for grazing livestock farms (1.03). Overall, livestock farms exhibit lower average coefficients of economic viability compared to crop production farms. This corresponds to findings in a Czech study [
7].
The median values of the observed indicator are expectedly lower, reflecting the significantly reduced level of economic viability among farms in the Republic of Serbia. The situation is particularly problematic in milk, mixed, and grazing livestock farms, where the median coefficient value is below one. The most endangered are definitely grazing livestock farms, which is in line with Hlouškova et al. [
12]. They not only exhibit the lowest average and median economic viability coefficients, but they also consistently recorded a share of economically viable farms below 50% (
Figure 1). In all observed years, the share of economically viable grazing livestock farms was the lowest, except in 2016, when mixed farms took on this role. Although, there are a noticeable number of farms with very promising prospects, the obtained results clearly indicate that the majority of grazing livestock farms face serious challenges in achieving economic viability. On the other hand, field crop farms generally recorded the highest share of economic viability, with the exception of 2015 and 2017. They were followed by permanent crop farms, which also exhibit the second-highest average economic viability coefficient among the remaining types of farming.
In order to accurately assess the economic viability of farms and the vulnerability of those that are not economically viable, the farms were divided into two categories: (1) economically viable—farms with an LTEV coefficient equal to or greater than one, and (2) economically non-viable—farms with an LTEV coefficient less than one (
Table 3). The proportion of economically viable farms is favourable, with 54.38% of the total observed farms being economically viable. The recorded LTEV coefficient of 4.15 in this category of farms is also beneficial, indicating promising prospects for the farms in general. The highest percentage of economically viable farms is recorded in field crop farming (61.30%), closely followed by permanent crop farming (60.71%). These two types of farming also achieve the highest LTEV coefficients within the category of economically viable farms.
On the other hand, the share of economically non-viable farms was 45.62%, with an average LTEV coefficient of −0.09. The negative value of the LTEV coefficient is highly concerning, indicating that farms achieving net loss dominate in this group. Grazing livestock farming recorded the lowest share of economically viable farms (38.78%), as expected. In the category of economically non-viable grazing livestock farms, the average LTEV coefficient is also extremely low, at just 0.04. This indicates that grazing livestock farms are the most endangered, as they are the farthest from the viability threshold among all observed types of farming. Grazing livestock farms are generally extensive farms, often located in areas with natural constraints. These farms are usually managed by elderly farmers who have never worked outside of agriculture. The reason is primarily that they are not capable of doing anything else due to their low qualifications. However, an equally important factor is the agricultural tradition they maintain. The emotional connection to the work they do is undoubtedly a key reason preventing them from leaving agriculture, even though they may not achieve the best economic viability outcomes. Nevertheless, the continuation of their activity is crucial for the development of the remote rural areas [
12] where these farms are dominant.
3.2. Exploring the Factors Affecting Farm Economic Viability
In order to examine the relationship between variables in the model, the Pearson correlation coefficient is applied. Due to the extensive data, the results are presented in the appendix (
Table A1,
Appendix A). The results indicate that the observed variables can be used in panel regression analysis, as only insignificant or weak correlations are recorded. A strong relationship is noticed only between the economic viability coefficient and economic size in milk farms, with a correlation coefficient of 0.7030. However, this result suggests a potential reverse causality [
44], meaning that the dependent variable (LTEV) might influence the independent variable (ES) in the model. According to the reviewed literature, no research analyzes the impact of the economic viability coefficient on the economic size of farms. The opposite influence of economic size on the farm viability is often observed in the analysis [
6,
19,
24] and is considered relevant.
Before conducting the panel regression analysis, the stationarity of the time series is assessed using the augmented Dickey–Fuller unit root test. The null hypothesis assumes that the time series have a unit root. Since the
p value is less than 0.05 in all types of farming (
Table 4), the null hypothesis is rejected. Accordingly, the alterative hypothesis, which assumes stationarity, is accepted.
The first step in panel regression analysis is to select the appropriate model among the Ordinary Least Squares (OLS), fixed effects model, and random effects model. The OLS model is unbiased and efficient when individual and/or time effects do not exist, making it essential to test for their presence. The existence of individual and time effects was tested using the F-test for fixed specification of the model. The results confirmed the presence of individual effects in all types of farming, as the
p value is less than 0.05 (
Table 5). On the other hand, the presence of time effects is recorded only in field crop and permanent crop farms (
p < 0.05).
In the random effects model specification, the existence of individual and time effects was examined using the Breusch–Pagan LM test. Based on the test results, individual effects are found in all types of farming, since the
p value is less than 0.05 (
Table 6). Conversely, the presence of time effects is confirmed only in field crop and permanent crop farms (
p < 0.05).
The confirmed presence of individual (and time) effects in all types of farming clearly indicates that OLS is not an adequate model to use. Therefore, it is necessary to use a model with individual and time effects for field crop and permanent crop farms, and a model with individual effects for milk, grazing livestock, and mixed farms. The next step in selecting the final specification of the model is to determine the nature of the effects, i.e., to choose between the model with fixed and random effects. For this purpose, the Hausman test was applied, with the null hypothesis assuming the appropriateness of the random effects model. Since the
p value is less than 0.05 in all types of farming except milk farms, the null hypothesis is rejected (
Table 7), indicating that for field crop, permanent crop, grazing livestock, and mixed types of farming, the fixed effects model should be used. The exception is milk farms, where the null hypothesis is accepted (
p > 0.05), suggesting that the random effects model specification is more appropriate.
After selecting the model specification, it is necessary to examine the basic assumptions for applying panel regression analysis. Regarding this, it is crucial to access the presence of multicollinearity. The test results indicate that the VIF values do not exceed 5, and the TOL values are not lower than 0.2 (
Table 8). This clearly confirms that there is no harmful multicollinearity in the observed models.
Finally, the models were tested for the presence of autocorrelation, heteroskedasticity and cross-sectional dependence (
Table 9). The presence of autocorrelation was tested using the Wooldridge test, and the results confirm the existence of first-order autocorrelation in the models of permanent crop, milk, and mixed farms (
p < 0.05). In the models of field crop and grazing livestock farms, the null hypothesis is accepted (
p > 0.05), indicating the absence of first-order autocorrelation. The existence of heteroskedasticity was tested using the White test. Since the
p value is less than 0.05 in all types of farming, the null hypothesis is rejected, indicating that heteroskedasticity is present in the models of all types of farming. Finally, the Pesaran CD test was applied to test for the presence of cross-sectional dependence in the models. The results indicate that there is interdependence in the models of field crop, milk, and mixed farms (
p < 0.05), while in the models of permanent crop and grazing livestock farms, cross-sectional dependence is not confirmed (
p > 0.05).
Considering that at least one basic assumption is violated, an alternative specification of the panel regression model with corrected standard errors (PCSE) was used in the research (the tested OLS, fixed effects model, and random effects model, as necessary steps in panel regression analysis, are presented in the appendix (
Table A2,
Table A3 and
Table A4,
Appendix A)). As far as the results of the previous tests have shown, the fixed effects model specification is the most reliable for use in all types of farming, except for milk farms. Following this, the results of the alternative panel model with fixed individual (and time) effects for field crop, permanent crop, grazing livestock, and mixed farms are presented in
Table 10. In milk farms, on the other hand, an alternative panel model with random individual effects was applied.
According to the F-test/Wald chi2 results, all models are statistically significant (p < 0.01). Relatively low values of the coefficient of determination, particularly in field crop and permanent crop types of farming (12.80% and 16.21%), are to be expected. Crop production is highly influenced by climatic conditions, soil fertility, and irrigation, none of which are included in this study. Unlike crop production, livestock production is managed under more controlled conditions, which is why the coefficient of determination values are significantly higher here.
The research results indicate that economic size has a statistically significant positive impact on economic viability in all types of farming, except for permanent crops (
Table 10). This is expected, as larger farms are better equipped with machinery and other technical resources. They also have larger land and livestock capacities, as well as newer and more modern buildings for storing finished crop products and housing livestock. That is precisely why these farms are generally characterized by higher labour productivity and production efficiency, enabling them to generate higher incomes and, consequently, achieve a greater level of economic viability [
6,
12,
24,
25,
45,
46]. Conversely, economic size does not have a statistically significant impact on the economic viability of permanent crop farms, which is in line with the findings of Ziętara and Sobierajewska [
23] based on research of fruit farms in selected Eastern and Western European countries.
Unlike economic size, the share of rented land and share of paid labour significantly impact economic viability only in one specific type of farming. The share of rented land has a statistically significant negative impact on the economic viability of mixed farms. A higher share of rented land increases the level of uncertainty in the organization and planning of production, particularly in crop farms [
25]. They cannot make long-term production plans or plant perennial crops, which directly impacts livestock production as well. For this very reason, mixed farms, which are involved in both crop and livestock production, are most negatively affected by a high share of rented land. Vira et al. [
26] go even further and claim that a high share of rented land can lead producers to quit agriculture, particularly in the case of small-scale agricultural producers. The share of paid labour, similarly, has a statistically significant positive impact only in permanent crop farms. These farms are highly dependent on paid labour, as the nature of the business requires the engagement of a large number of workers during specific, short time intervals. This, of course, cannot be accomplished solely with unpaid labour input. Therefore, the motivation of paid labour [
22] and job quality play a crucial role, directly influencing the results achieved in permanent crop farming. Paid labourers are specialized in the tasks they perform [
47] and, as a rule, achieve higher labour productivity compared to unpaid labour, which typically consists of family members [
48,
49]. Finally, employing paid labour also entails higher labour costs, but at the same time, it enables farms to generate significantly higher incomes, ultimately leading to a higher level of economic viability.
The farmer’s age has a statistically significant negative impact on the economic viability only of mixed farms, at the 5% level. The negative impact of the farmer’s age is expected, considering that older farm managers are usually less willing to innovate and make significant changes to the production process. They generally have less energy, find it more difficult to adapt to new technology, and are less willing to increase the intensity of agricultural land use [
50,
51]. Unlike older farmers, younger farm managers are well educated and adapt more quickly and easily to market changes [
27]. They consistently stay informed about the latest legal regulations [
33], agricultural competitions and generally keep up to date with important information relevant to agricultural production.
The asset turnover ratio is the only variable that has a statistically significant impact on the economic viability of all types of farming. It has a positive and highly statistically significant impact at the 1% level, except in the model for milk farms, where the level of significance is 5%. The results indicate that farms with a higher asset turnover ratio achieve higher economic viability coefficients, which is consistent with research conducted by numerous authors [
22,
45,
52,
53]. A faster turnover of assets logically indicates a shorter production cycle, meaning a higher intensity of production. The higher intensity is very important for better capacity utilization, which provides more efficient production. This is, certainly, related to the generation of higher incomes, which consequently leads to a greater level of economic viability of farms. Hence, farm managers should aim to further reduce the production cycle wherever possible, by using fast-growing crops and livestock units with the best genetic potential.
Further, agricultural diversification has a statistically significant negative impact on the economic viability of field crop farms at the 1% level. Employees on diversified farms must invest significantly more time and effort in performing various tasks on the farm [
30]. Unlike them, workers on specialized farms can achieve better results as they are trained for just one or a small group of specific tasks. Accordingly, greater farm diversification could lead to a decrease in efficiency or labour productivity [
48] and, ultimately, a reduction in economic viability level. This is particularly characteristic of farms engaged in crop production [
54], as is the case with field crop farms. These farms often lack adequate mechanization and other necessary equipment, as well as sufficient labour input to efficiently perform the various tasks required for diverse crop cultivation.
Finally, the subsidy level does not emerge as a variable with a statistically significant impact on the economic viability of farms. It is important to emphasize that only current operations related to production are included here, while subsidies on investments are not. By investing in assets, farms enable more efficient resource utilization, which positively impacts their development opportunities [
55]. The effect of subsidies, on the other hand, is insignificant, primarily due to the nature of the subsidy schemes in RS. As direct payments are dominant in income support, this could influence the lack of motivation among farmers to improve farm performance [
56]. The insignificant effect of subsidies on farm viability is also recognized in Scottish farms [
16], which imply the long-term resilience of farms in relation to public support. Slijper et al. [
9] take it a step further, arguing that farms receiving more direct payments have a lower probability of being economically viable in the long term. The main reason is that a higher share of subsidies in total income could indicate subsidy inefficiency. Obviously, the current support program in RS does not provide adequate gains for farmers. Direct subsidies, which dominate the subsidy structure, primarily serve as income support, disregarding support for improving farm performance. In line with this, there is a need for agricultural policymakers to focus more on the product quality and efficiency of resource use in order to fully realize the effects of subsidies.