The influence of soil parameters on the price of agricultural land in Slovakia

ABSTRACT The article analyses the relation of market prices in the agricultural land market and selected pedological characteristics of traded lands. During the period of 2009–2018 in 12 districts of Slovakia more than 153,000 plots with different pedo-ecological and geographic conditions have been analysed. Based on soil types, texture composition, steepness, gravel content, and depth, corresponding price levels were derived, and soil price maps were developed. The highest valued soils are of chernozem type (EUR 1.64 m−2), loamy soils (EUR 0.86 m−2), soils on flat land (EUR 1.09 m−2), slightly gravelly soils (EUR 1.02 m−2), and deep soils (EUR 1.10 m−2). The land price is evidently highly correlated with its qualitative parameters. Using GIS technologies, the entire territory of Slovakia has been categorized by this means and a so-called basic map of agricultural soil market prices in Slovakia has been created.


Introduction
The major part of agricultural land in Slovakia is cultivated in a form of land leasing.Only a small part is cultivated by land owners themselves.It is, therefore, necessary to create such mechanisms that could facilitate the acquisition of land as basic means of production to start, as well as for experienced farmers.Research and analysis of the factors affecting the agricultural land market, as well as the condition and quality of the land itself, play a very important role.Nickerson et al. (2012) report that land quality is positively correlated with land price.According to him, land prices are up to 5% higher for plots with good quality soils compared to those with poor quality soils.
Research works dealing with the issue of soil price are progressively appearing also in Slovakia.The market with agricultural land as a piece of real estate is a part of the municipal market system, its partial market, which comes under the general market rule with certain unusualnesses, determined mainly by natural conditions.It can be stated that this extent is given not only by the production capacities of particular agricultural soil, or rather plot but also by economic attractiveness, especially of the location of the plot.Different extents of the local market will occur in agricultural production areas, in recreational and tourist areas, and surroundings of big cities.Buday and Vilček (2013) and Pavličková and Spišiak (2007) are stating that when determining land prices, the profitability of agricultural production is the decisive factor and that the most favourable land prices are where the soil is fertile and the land is not spatially divided.They state as well, that high prices are achieved during the conversion of agricultural lands into residential lands.According to Ciaian et al. (2011), the increase of land prices in the EU is considerably influenced by the type of support policy in individual member states.The amount of payment per hectare is different in each country, thus the pressure on land price varies.The land price is influenced by the budget for direct payments as well (Michalek et al., 2014).Hamza and Miskó (2007) document, that before the accession to the EU, the land prices and land leases significantly increased, proportionally in accordance with the quality of the soil.Lazíková and Bandlerová (2006) state in their research, that factors, which are currently influencing market prices of agricultural land during the purchase and sale are: the demand and the offer in the place of location of land plots, the macrolocation of land plots (location of districts within the country), micro-location of land plots (location of lands within the district), access to the land, infrastructure, production capacitysoil value.The relationship between land price and plot size is a subject of a study by authors Ritter et al. (2020).
The purchase price is a factor, that changes depending not only on soil quality and soil value but also on the attractiveness of the area where the plot is situated.For example, the construction of highways or industrial parks represents for the farmer a risk of expropriation, therefore he is more likely willing to rent rather than buy the plot.Purchasing of the plot would be preferred only if its market price would be sufficiently low and interesting even in the case that would allow the farmer to farm on it for a few years only.On the contrary, rare cultural, natural, or historical discoveries or the creation of recreational areas could attract new entrepreneurs, and potential purchasers and thus also new potential customers (tourists, but also inhabitants attracted by new job opportunities).Naturally, it would increase the attractiveness of agricultural land in the eyes of the farmer, who will be willing to pay a higher price to acquire it (Lazíková & Takáč, 2010).The price of agricultural land is also influenced by the fragmentation of soils, as found by Cotteleer et al. (2007).
As stated by Baran et al. (2012) the amount of soil price is influenced also by the tax burden determined by the municipality.Land tax is individually levied by each municipality, which may also have an impact on the final land price.The purchase of land by foreign legal entities in 2011 was analysed by Buday et al. (2013).Authors discovered that foreign legal entities have purchased only plots within the size category up to 1 ha.According to Kováčik (2011) the issue, or rather benefit from the acquisition of agricultural land beyond the frontiers of the country of origin represents a global phenomenon.On the one hand, there are positive effects of agricultural land acquisition, which could be the expertise of farmersforeigners and the supply of new technologies, but on the other hand, there are negative effects as well, mainly in land speculations.They could have a negative impact not only on the economy of the country but also on the well-being of its citizens.
The objective of the article is (a) to analyse relations and dependencies between the quality of agricultural land in selected model regions and its price by way of an example of relatively stable parameters, for which there is sufficient data (databases, maps) in Slovakia, (b) to create a basic map of market prices of agricultural land for the entirety of Slovakia.

Methods
To determine the price levels (potential prices) of agricultural land depending on the main soil characteristics (physical parameters), we used databases (data) from already realized commercial transactions, i.e. prices from real sales of specific agricultural land.Databases on the spatial distribution of the assessed parameters (soil type, grain size, slope, stoniness, depth) of agricultural soils in Slovakia were used as well.Each category (Database of soil parameters chapter) of the assessed soil parameter associated with the sale location was assigned a price value according to the sale agreement.Since the spatial distribution of the assessed parameters in Slovakia is thoroughly mapped (also in the form of vector maps), the correlation between price and soil parameters allowed us to implement the analysed relationships on all agricultural soils (not only on the sale locations).The resulting price (final map) represents the value calculated as the average of the prices for each parameter (chapter Methodical process of work).

Database of evidence on purchase and marketing of soils
The database of evidence from the Soil Value Databank of the Research Institute of Agricultural and Food Economics in Bratislava, where data on the development and amount of market prices of soil for 12 districts in Slovakia are collected, was used in our analysis.The database contains the following data: plot number, code, and name of the cadastre and district of the land sold, area of the plot in m 2 , type of land (type of use), year of sale, and the price at which the sale was made in EUR.Data on land prices in selected model districts of Slovakia for the years 2009 to 2018 were analysed.Territories of districts were chosen so that they represent heterogeneity of soil-climatic conditions, geographical (geomorphological) characteristics as well as regionalisation of economic parameters of Slovakia (Figure 1).
Selected districts (Dunajská Streda, Trnava, Nitra, Topoľčany, Žilina, Banská Bystrica, Liptovský Mikuláš, Rimavská Sobota, Košice, Prešov, Svidník, and Michalovce) cover 26.3% of the total area of agricultural land in Slovakia.They sufficiently represent the agri-climatic and production conditions of lowlands, basins, and hilly and mountain areas as well.The subject of trading and thus also our analysis was more than 153,000 land plots (108,000 arable land plots, 40,000 permanent grassland plots, 960 plots of vineyards, 4000 garden plots, 230 orchards plots), which represents the annual average of approximately 15,000 trade cases.

Database of soil parameters
Materials for analysis of the correlation between soil parameters and price levels were drawn from databases and sources of Soil Science and Conservation Research Institute (soil portal of SSCRI: http://www.podnemapy.sk/default.aspx),which owns and operates relevant information sources and provides information services on agricultural soils of Slovakia.SSCRI owns and utilises a database on the spatial distribution of soil qualities in vector format, which allowed us to obtain detailed information on soil parameters of analysed plots.Categorisation of soil parameters is following the methodology, that is usual in the bonitation of agricultural soils in Slovakia (Džatko & Sobocká, 2009).

GIS and statistics interpretation
Processing of gained data, interconnection of databases, and spatial interpretation of obtained results required the use of tools and methods enabling their effective analysis and synthesis.In this regard, the application of GIS tools emerged as the best solution.
The GIS ArcMap, as part of the programme package ArcGIS, was used.The mentioned GIS tools we used consisted of the following steps: . Spatial identification of plots contained in the market price database (registry of agricultural plots sales in Slovakia in the 2009-2018) was performed via a cadastral map.The connection between both databases was made using cadastral ID. .Intersection of sold plots vector features class and soil properties vector features class (SSCRI spatial database) in GIS was used in correlating the relationship between the characteristics of agricultural land and its price. .The agricultural soil potential price for the whole of Slovakia territory was derived from a spatial database of soil properties (see Section 2.2) using the above mentioned/derived correlation relations. .The resulting price of a specific locality (of soil) was determined as the average of prices determined from partial soil parameters (soil type, texture, steepness, gravel content, depth) on the condition of their equality.
The dependence of soil prices on the analysed soil properties was tested by correlation and regression analysis (by linear function) only in cases of their logical sequence (categories of steepness, gravel content, and depth).For determining dependence between the evaluated variables (e.g.slope and its average market price) statistical methods were used, mainly correlation analysis, which is exploring the relations between variables using different rates of dependence (correlation coefficients).Correlation coefficient measuring the strength of statistical dependence between two quantitative variables: where x and y are mean values of arithmetic means of corresponding variables to a given extent.
For the statistical evaluation, the statistical software SPSS (Spatial Package for the Social Science) and software NCSS (Number Cruncher Statistical Software) was used in addition to Excel analysis tools.The obtained results are presented in the form of graphs and figures.

Methodical process of work
Used material, methods, and work process, leading to the fulfillment of the objective and achievement of required results, are illustrated in Figure 2 in schematic form.

Results
The value (price) of any matter or product should reflect its quality and beneficial effect.It is not different either in the case of soil.In general, by soil quality, we understand a set of properties and parameters influencing the fulfillment of its production as well as non- production (environmental) functions.From the time perspective, the soil parameters can be as follows: a) staticin a short term in a given area, they are not subject to a significant change (soil type, steepness depth, gravel content, texture etc.), b) dynamicthey change in time and space (chemism, soil management etc.), we consider that the value of the land should primarily reflect its static parameters and the dynamic or socio-economic parameters should be taken into consideration subsequently as well.
The relationship between land price and land quality was tested by regression analysis.Soil type, soil grain size, steepness of soil, gravel content and soil depth were selected as quality parameters.

Basic data on the price of agricultural land
The majority of agricultural land in Slovakia is not farmed by the owners.They lease out the land to farmers, and often do not even know how they handle it.The relation of the owner to the land was disrupted by the period of socialism and agricultural collectivisation.From the 1950s until the 1990s, agricultural land was utilised in form of so-called farmers' cooperatives or state-owned enterprises.The land belonged to the owners only formally (de jure yes, but de facto no).The user was the one who decided on its use.After the fall of communism in 1989, the gradual return of land to its original owners happened.Over time they started to realise its value and the interest in this commodity slowly increased as well.Rather than its qualitative properties, the land price depended on its position parameters (proximity of the market, possibility of change of land use, e.g. for residential use, etc.) and in accordance with the possibility of agricultural subsidies set by the State per area unit, as well as parameters of their size.
The real value of soils for farmers is, although, slowly but surely beginning to depend on parameters that guarantee its effective productive capability.On the one hand, quality soils reduce production costs, and on the other hand, they naturally increase crop production.At the turn of the nineteenth and twentieth century, the interest of farmers to cultivate their own land, as well as the land market (albeit fluctuated) in Slovakia came to life.
Per the research period (2009-2018) and localities, the average price of agricultural soils was EUR 0.82 m −2 , while in individual years it ranged in the interval from EUR 0.48 to EUR 1.39 m −2 (variation range 0.91).The subject of purchase and sale in the regions monitored by us was 51,476 ha of land (which is about 2% of the total area of agricultural land in Slovakia) with an average size of 3362 m 2 .Of the total area of traded lands, arable lands were the most represented (up to 67.6%).More detailed data, broken down by agricultural land-use types are included in Table 1.
In the monitored period, the price of arable lands ranged from EUR 0.55 to EUR 1.66 m −2 (variation range is 1.11).In the case of permanent grasslands, this interval was from EUR 0.34 to EUR 1.39 m −2 (variation range is 1.05) and in the case of agricultural land in general the interval ranged from EUR 0.48 to EUR 1.39 (variation range 0.91).In the case of vineyards, the price of soils ranged from EUR 2.09 to EUR 7.36 m −2 (variation range 5.25), in the case of gardens from EUR 6.40 to EUR 20.91 m −2 (variation range 14.51), and in the case of orchards it was from EUR 0.39 to EUR 14.87 m −2 (variation range 14.48).Variability of land prices in the case of so-called special cultures (land-use types) is thus multiple times higher as it is in the case of arable land and permanent grasslands.Agricultural lands situated within the urban area of municipalities and cities were traded for the average price of EUR 3.20 m −2 .

Soil type
The distribution of soil types in the country is the result of soil genesis in different geographic (geological, morphological) and climatic conditions.The most advantageous soil types for agriculture are the ones, that, based on their physical, chemical and biological parameters provide long-term high sustainability of their production possibilities.They are mostly structural, nutrient-rich, biologically active soils with good air and water conditions.A good distinctive mark of these properties is the soil categorisation by soil type and, consequently, the resulting price.
It is thus logical, that the land market should take into account the soil type as a basis for the determination of land price.In the conditions of Slovakia, the dependence of land prices on soil type is relatively high.The highest valued is the soil type of chernozems (EUR 1.64 m −2 ) and the least valued soils are the soil types of solonetz and solonchak soils (EUR 0.07 m −2 ).Relatively high valued are also soil types of cutanic luvisols (EUR 1.13 m −2 ), molic fluvisols (EUR 1.03 m −2 ), cutanic albic luvisols (EUR 0.95 m −2 ), and fluvisols (EUR 0.91 m −2 ).In the middle price range, we place regosols and rendzinas (EUR 0.72 m −2 ), planosols and cambisols (EUR 0.71 m −2 ).Much less valued are podzols (EUR 0.48 m −2 ), gleysols (EUR 0.28 m −2 ) and leptosols (EUR 0.13 m −2 ).
Taking into account the soil types, up to 52.4% of agricultural land is within the price level from EUR 0.61 to EUR 0.80 m −2 .
The map of land prices based on soil types in conditions of Slovakia is presented in Figure 3.

Soil texture
The most appreciated soils by agricultural practice are the soils with good structure (soil texture composition of individual size fractions).These soils have a favourable water-aerial regime, they are good for cultivation and can provide an effective substance and energy flow between the soil and the plant.From this perspective, the best soils seem to be the medium-heavy, loamy soils with a content of a fraction of <0.01 mm in the interval from 30 to 45%.The worst soils seem to be very heavy, clay soils with a content of fraction <0.01 mm above 60%.
Price levels of soils, which were the subject of purchase or sale in Slovakia in the period from 2009 to 2018 confirm the impact of the parameter of textural composition of soils on the final price.In this perspective, the most expensive soils were the loamy soils (EUR 0.86 m −2 ) and the cheapest soils were the clay soils to clays (EUR 0.36 m −2 ).Clay-loamy soils (EUR 0.66 m −2 ) and sandy-loamy soils (EUR 0.59 m −2 ) were moderately priced.
Taking into account the textural composition of soils, more than half (59.5%) of them belong to the category of price range from EUR 0.81 to EUR 1.00 m −2 .Price disparities of agricultural lands based on their textural composition in the territory of Slovakia are presented in Figure 4.

Steepness of soils
Ruggedness, but mainly the slope of the surface significantly influences the production as well as the economic potential of soils.The soil on slopes is, to a greater extent, exposed to adverse impacts of water erosion, its cultivation is technically more demanding and the crop growth requires increased intensification inputs.The analyses of the relation between the steepness of soil slope and soil prices confirm our assumption, that as the surface slope increased, the price of soils linearly decreased.
While the price of plots at flat land (up to 1°) reaches on average the amount of EUR 1.09 m −2 , the price of plots on slopes over 25°is only EUR 0.11 m −2 .The price on slopes between 1 and 3°is EUR 0.89 m −2 , on slopes between 3 and 7°EUR 0.86 m −2 , on slopes between 7 and 12°EUR 0.68 m −2 , on slopes between 12 and 17°EUR 0.47 m −2 , and on slopes between 17 and 25°EUR 0.32 m −2 .Based on the steepness of the slope, most agricultural soils (40.00%) fall into the category of price range from EUR 0.81 to EUR 1.00 m −2 .Spatial differentiation of soil price with regard to the real slope of agricultural soils in Slovakia is presented in Figure 5.

Soil gravel content
The content of the soil gravel influences mainly the possibilities of soil cultivation, usability, and wear of agricultural machinery, and finally also the economy of farming.Our analyses show that this soil parameter, contrary to other assessed soil qualities, does not play a significant role in the case of land price.The aforesaid fact is also confirmed by the relatively low variation range of prices among individual categories of gravel content (EUR 0.37 m −2 ).
It is interesting, that in this regard, slightly gravelly soils (EUR 1.02 m −2 ) were, in comparison valued more than non gravelly soils (EUR 0.86 m −2 ).Medium gravelly soils (EUR 0.76 m −2 ) and very gravelly soils (EUR 0.65 m −2 ) were valued, as expected, the least.
The correlation dependence of soil price and soil gravel content, determined by us, influenced the resulting map of spatial differentiation of this relation mainly in the case of non gravelly soils (Figure 6).

Soil depth
Another important parameter determining the quality of agricultural soils is their depth.The greater the soil depth, the higher is the potential to provide necessary nutrients to plants, and the space for better development of the root system of grown crops increases as well.This parameter is relatively stable, changing only in cases of dramatic natural, or rather anthropic  events or interventions.Our research confirmed a positive correlation between the price and depth of soils.In the evaluated data set on soil price, deep soils were double the price in comparison with shallow soils (EUR 1.1 or 0.56 m −2 ).Medium deep soils were in average EUR 0.88 m −2 .Spatial differentiation of soil prices depending on soil depth is presented in Figure 7.

Basic price and map of agricultural soils arising from their static parameters
The analysis of agricultural soil prices depending on evaluated parameters enabled a synthesis, resulting in a calculation of the recommended final value of soils.In our case, all analysed parameters had the same weight.The resulting price represents the weighted arithmetic average of prices by individual parameters.Using the GIS technologies, each locality of registered agricultural land was assigned the price resulting from our algorithm.This price is presented in Figure 8 (Main Map).Up to 57.8% of agricultural soils are in the price range from EUR 0.81 to EUR 1.00 m −2 .The average price of agricultural lands for the entire Slovakia, determined based on the application of evaluation of analysed soil parameters for the entire Slovakia is EUR 0.92 m −2 .It is thus slightly higher, as it was in the case for the analysed areas.In the case of arable  lands, this price is, the same as in model areas, EUR 0.96 m −2 .In the case of permanent grasslands, it is EUR 0.83 m −2 , which is significantly higher than it was in the case of model areas.
The practical role of the application of the map, after the use of zooming, is to provide information on the basic price of agricultural soils, which can subsequently be regulated, in relation to the position parameters of the land.Evaluation of position parameters will be the subject of our following research.

Conclusion
Buyer and seller should know the characteristics of marketed land.Knowledge of the parameters of the particular land can significantly facilitate the agreement of the involved parties.The aim of this study was to point out correlations between so-called static properties of agricultural soil (soil type, texture, soil slope, gravel content, and soil depth) and price levels in the land market in Slovakia in the period from 2009 to 2018.The obtained results confirm the assumptions and conclusions of other authors on the dependence between the quality of soils and their price.Price levels determined by us (based on analysis of relations between soil prices and soil properties in model areas) of agricultural lands in Slovakia showed, that these correspond to the trends in neighbouring countries.The average price of agricultural lands in Slovakia set based on the application of evaluation of analysed soil parameters for the entire Slovakia is EUR 0.92 m −2 .Practical outcomes of the study are the price map of agricultural soils of Slovakia, as well as partial maps of land prices depending on their particular properties.
At the same time, we state that so far in the available literature, we have not encountered an analysis of land price related to the specific soil parameters evaluated by us.We consider the results presented in the study as one of the steps to calculate the objective price of soil, that will correspond to market conditions as well as the natural environment.The next step, we envisage to undertake in this regard, is the analysis of positional parameters (size, distance from cities, municipalities, etc.) and their subsequent synthesis resulting in an even more accurate agricultural soil pricing scheme.
The results obtained from analyses create a database, used for the decision-making sphere, mainly for the creation of conceptions and directions of common agricultural policy for the next period.The results of the solution related to the level of market prices can be further used in working out the analysis in the field of the agricultural land market.They can also serve a wide range of agricultural practices in the form of professional consultancy services.Further use of the results is possible in the scientific and research sphere, in publication activity, and building of complex soil information systems.

Software
The maps were created and edited using Esri ArcGIS 10.3.Spatial analysis, calculations, and statistical analyses were also performed in ArcGIS 10.3.The main graphics were created using CorelDRAW 2018.

Disclosure statement
No potential conflict of interest was reported by the author(s).

Funding
This work was supported by the Operational Programme Integrated Infrastructure within the project: Scientific support of climate change adaptation in agriculture and mitigation of soil degradation no.313011W580, cofinanced by the European Regional Development Fund; and supported also by the Slovak Research and Development Agency under grant number APVV-15-0406 and agency VEGA grant number 1/0100/22.

Figure 1 .
Figure 1.Spatial dislocation of analysed districts of Slovakia.

Figure 3 .
Figure 3. Spatial differentiation of soil prices based on soil type.

Figure 4 .
Figure 4. Spatial differentiation of soil prices based on their texture.

Figure 5 .
Figure 5. Spatial differentiation of soil prices based on the steepness of slope.

Figure 6 .
Figure 6.Spatial differentiation of soil prices based on gravel content.

Figure 7 .
Figure 7. Spatial differentiation of soil prices based on soil depth.

Figure 8 .
Figure 8. Map of the basic price of agricultural soils depending on static soil parameters.

Table 1 .
Distribution of land-use types, their average size and price of traded agricultural soils in Slovakia in the period of 2009-2018 in the examined sample.