The characteristics of the natural conditions of the region (i.e., the landscape, climate, physical, chemical, and biological components of the soil and rock) comprise a vital part of the terroir [1
]. The modern experience of the ampelo-environmental research in viticulture [4
] has shown that the accounting plays an important role along with the geomorphologic and microclimatic characteristics of the area, including the soil-ecological characteristics, such as profile thickness, granulometric composition, bulk density, humus and carbonate content, pH, and presence of unfavorable properties (e.g., stoniness). These features are particularly evident in the transformation of the soil in the ancient agricultural fields in arid and semiarid regions [7
]. The grape has a very well-developed root system; thus, it is characterized by a high ability to extract nutrients from the root layer of the soil, but at the same time, the plant is rather sensitive to environmental factors. Consequently, under different conditions, the plant may yield different harvests in terms of quantity and quality [8
]. Since the quality of wine is affected by almost all soil properties and soil fertility, these factors explain the vital role of ampelopedology, which produces the results of genetic soil studies for viticulture [9
] and the establishment of a correspondence among the chemical composition of grape, the geochemistry of vineyard soil, and the geolithological features of cultivation zone [10
]. According to the concept of “terroir”, the soil in which grapes are grown plays a major role in the vine behavior, the grape quality, and the wine sensory characteristics [11
]. Thus, for example, the method developed in France for characterizing viticultural terroirs uses a field soil model based on the type of parent rock, as well as the depth and the clay richness of the soil, mainly in connection with the weathering level of the parent rock [13
]. The role of the contents of trace elements (Co, Ni, Mn, B, Zn, etc.) in the soil is just as important for growing high-quality grapes as is the content of the fundamental mineral elements—N, P, K, Ca, S, and Mg [4
]. However, the impact on the productivity of trace elements and in particular of heavy metals depends largely on the soil environment in specific bioclimatic conditions [18
]. Furthermore, fine-dispersed minerals (silt and clay) appear to be the most relevant soil parameters controlling soil dynamics in the profile of soils and parent rock [23
In viticulture, it was noticed long ago that the best wines usually grow in shallow soils where the rocks exit to the surface. Obviously, in this case, the quality of wine depends not on the physical properties of the soil, but on the mineral nutrition that the grape receives from the rocks. According to the opinion of V. Akimtsev [24
], the quality of wine depends on the entire complex of natural factors; however, the key factors include rocks that have not been completely destroyed and individual elements that are extracted by the grape roots and are accumulated in the grape juice. These elements are further accumulated in wines and affect the wine characteristics [24
], which markedly vary from grapes grown in the same soils that have different parent rocks. In such cases, the absorption of the rare elements contained in the rocks may occur in a more concentrated form.
The Crimea Peninsula has a wide variety of soils, orographic and climate conditions; this includes the sub-Mediterranean variation along the southern Crimean coast, which is a region with a long history of viticulture. Tauric Chersonesos was the biggest center of ancient viticulture and wine production along the northern Black Sea coast, and wine was the main export of this Greek city. The agricultural hinterland of the ancient city of Chersonesos on the Herakleian Peninsula (south-west Crimea), known as the chora
of Chersonesos functioned for a long period, starting from the period of the initial establishment of Greek farms (ca. 5th century BC) to the beginning of the 1st century AD. Vitis
pollen marks the beginning of viticulture by the Greeks ca. 400 BC [25
]. Agro-landscapes of different ages formed during the lifespan of ancient Chersonesos and medieval Cherson.
The climate and its changes within the last several thousand years are very important for the development of viticulture and the formation of biogeochemical properties of soils and rock. The climate in the western part of the Crimean Peninsula is a mild steppe in the plains and transitions to sub-Mediterranean in the southwest.
The study of palaeosoils of barrows belonging to the Eneolithic Age, the Bronze Age and the Middle Age, are located within the modern steppe area, and these studies have shown the rhythmic changes of watering conditions with several periods of aridization [26
]. The speed of soil mineral weathering cannot be considered as the single source of cations in the soil, as other sources of cations in soil are related to a higher level (compared to rock weathering) of mineralization of necro-material, including humus [27
]. These processes considerably depend on the “soil climate” and its changes over the Late Holocene. The acceleration of all soil processes occurs when there is an increase in humid climates, including slow increases; specifically, argillization, superdispersity of clay minerals, and changes in elemental composition occur [28
In the northern Black Sea region at the turn of the 4th and 3rd centuries BC, the cool and humid climate abruptly changed into a warm and dry climate. This, according to archaeological data [29
], led to the development of wineries with large-volume reservoirs, and wineries began to open more frequently in the cities as well as in the villages. During this period, the climate was hot and dry, but it changed into a more humid climate with two dry phases [31
] before the farms were abandoned (Byzantine period). From the beginning of the 1st century AD most farms of the chora
Chersonesos were abandoned as winemaking declined [32
]. Despite this decline, various farms remained active during the Roman and Byzantine periods, apparently focused on gardening [32
]. The long-fallowed lands have suffered two phases of humid and dry climate [33
] that could affect the conservation of the palaeomorphic features of agrogenesis. When croplands are abandoned, the starting conditions for the restoration process largely depend on the site-specific ecological characteristics (i.e., soil type, climate, former crops, field area, and availability of propagules) [34
]. However, it can be assumed that the secondary succession (i.e., the recovery of plant communities on regenerating soil) will not fully erase evidence of the ancient agrogenic loads.
New knowledge can be obtained by using existing developments in modern ampelopedology for the purpose of exploring the areas of ancient viticulture. The hypothesis of this work was to determine whether the environmental conditions, especially the properties of soils and rock in North-Western (NW) Crimea, limited the development of viticulture (with export potential in quantity and quality) in the formation of the distant chora of Chersonesos during the 4th and 3rd centuries BC.
The present study aimed to use an interdisciplinary approach that could integrate the methods of Archaeology and Geosciences for the study of ancient perennial plantations (vineyards and gardens).
Soils of the Herakleian Peninsula are distinguished by high contents of phosphorus and iron relative to other areas of ancient viticulture. The features of the parent rocks and the process of soil weathering in hot climates, such as that on the Herakleian Peninsula, lead to the enrichment of brown soils with iron oxides, which give red wines of an intense color [24
], and a golden tone to some white wines [8
Considering the fundamental differences in the geochemistry of parent rock and their soils, the most significant differences in the contents of macro and trace elements were defined for the areas of the Herakleian Peninsula and NW Crimea (Table 1
), that could potentially affect the quality of wine produced in those regions. Table 1
does not include the chemical elements for which the contents were below the detection limit, nor does it include the elements with a low coefficient of variation (V ≤ 10%): Ti, Mn, Co, K, Rb, Na, As.
Based on Table 1
(concentration of the most informative six macroelements and seven trace elements), data cluster analysis (Figure 2
) was performed, and the results showed that coastal (OT and K–L) and inland (OR and MT) areas of NW Crimea with certain differences still formed a common cluster (group III) and were significantly different from plots in the Herakleian Peninsula (groups I and II).
The most informative geochemical indicators and average values by groups are presented in Table 2
Four geochemical indicators (FI, Km, Ka, KS
) of seven indicators (Table 2
) showed higher values in group III (soils of NW Crimea), and the smallest values in group II, while group I occupies an intermediate position (soils in the area of Cape Fiolent). The eluviation’s coefficient (Ke), which by its structure gives inverse values from the four indicators mentioned above, confirms this pattern. Thus, soils from areas of NW Crimea are characterized by a more active accumulation of trace elements, reduced migration mobility, and degree of weathering in the more alkaline conditions of soil solution.
The studied soils in relation to the parent rock (Table 3
) are characterized by the greatest accumulation of phosphorus (average S/P ratio is 2.1), as well as Si, Zn, K, Cu, Mn (1.4–1.2). However, the soil of the two cuts (plot CN 130) is especially noticeably different from all other objects in the accumulation of Si, Fe, Al, K, Ni, Cu, Co, Mn. In addition to the plot of CN 130, a significant accumulation (above average) was noted for the objects OT, OR (trenching soils of NW Crimea), CN 395 and CN 391-1.
For a more detailed analysis, we selected the most contrasting objects from the plots in the Herakleian Peninsula: calcareous rendzina soil (CN 3) and cinnamonic soil at Cape Fiolent (CN 387), which primarily differ sharply in the content of CaCO3
: 7.3% (CN 3) and 59.5% (CN 387) (Table 4
Soils of the NW Crimea are carbonate Chernozem and rendzina soils, the last are sometimes met in the Herakleian Peninsula. Such soils have high carbonate content, moderate and strong alkaline reaction of soil solution, deficiency of available P2
(see Table 4
). The soils of NW Crimea, when compared to the plots in the Herakleian Peninsula, have a significant participation of magnesium and sodium in the cation exchange capacity, because of which the soils are less structural. The resulting regression equation showed that with increasing carbonate content (CO2
) from 3% to 27%, the CEC value was halved. Among the studied soils, only two cinnamonic soils near Cape Fiolent (CN 387 and CN 389) had a higher soil absorption capacity.
A comparison of the soils under the vineyards of an aggregate of 20 chemical elements showed a fundamental difference between the geochemical environment in NW Crimea, which is in a natural state [37
]; this was a result of trenching soil that inherited (obtained) a great influence of eluvium of dense carbonate rocks, and soils in the Herakleian Peninsula were due to a large area where there were spatial differences in the soil features. This primarily relates to the geochemical specificity of soils in the area of Cape Fiolent in comparison with the other areas of chora
The analysis of differences among the four objects in NW Crimea and key objects in SW Crimea (CN 3 and CN 387), according to the values of the factors Shaw (Ka) and KS
, showed the highest concentration of 12 trace elements in the soil CN 387 and the smallest in the soil CN 3, respectively (Table 2
). This showed that in the Herakleian Peninsula, there are spatial differences in the geochemical composition of soils under ancient vineyards. Carbonate rendzina soil (CN 3), in contrast to the other soils in the plots in the Herakleian Peninsula, was the closest to the objects in NW Crimea, and they differed only by a higher Ke value and smaller values of the other factors FI.
In NW Crimea, the same characteristics of the accumulation of trace elements are marked for OT, K–L, OR, and the most depleted soil is under the vineyard MT. This is because, compared to three other objects in NW Crimea, this object has less value S/P in 9 elements of 20, including essential elements—Mn, Fe, Ni, Cu, and K analyses of the accumulation of the trace elements in four objects in NW Crimea showed that they were united by the accumulation of 5 to 9 trace elements in the soil, but the most frequent elements were included in the array: (Zn, Ni, V) > Pb > Co > Rb > Cr > Cu > Mn.
Geochemical specifics of the soil in the plot CN 387 were determined by higher values (>1) of the ratio of the elemental concentrations to the average content in the soils of NW Crimea, and the plot CN 3 demonstrates the array (Pb, Fe) > Cu > Ni > V > (As, Rb) > MnO > Cr, and also lower concentrations Mg, Co, Sr.
Based on the studied Crimean soils of ancient land use, we can determine the overall number of accumulated chemical elements in the soil relative to the parent rock (S/P): P > Zn > (K, Mn) > (Co, Si) > Cu > Ni > Fe > Al. Three groups of objects that are reflected on the dendrogram vary in the number of chemical elements that accumulated in the soil relative to the parent rock: in I, III, and II groups—10, 7, and 5, respectively. The descending arrays of the accumulated elements for the three groups reflect their differences:
I group: Co > SiO2 > Cu > MnO > K2O > (Fe2O3, Ni, Zn) > (Al2O3, P2O5);
II group: Zn > (SiO2, P2O5, K2O) > MnO;
III group: P2O5 > Cu > Co > (Ni, Zn) > (MnO, K2O).
The elements that most distinguish the groups from one another are Fe, Al, Ni, Cu, Si, Co. In all groups there is accumulation of P, K, Mn, Zn.
Geochemical correlations and factors may determine the results of processes that are linked with parent rock weathering and pedogenesis. In our study, the most informative factors were FI, Ke, Km (Table 2
). The highest values of FI are noted in soils of NW Crimea due to the higher calcium content, as well as phosphorus, but not in all cases. The soils of this region have on average a greater CEC value (1.2 times) than the soils of the Herakleian Peninsula, which is associated with a greater participation of absorbed magnesium and sodium in the composition of the CEC.
The soil in the plots CN 387, such as most of the other objects in the Herakleian Peninsula, differed from the four objects in NW Crimea; specifically, had higher values of Ke and ratios Rb/Sr, (Fe + Al)/(Ca + Mg + Na). These values characterize the deeper processes of weathering and the removal of mobile elements that were related to longer farming duration near Chersonesos; additionally, these values reflect the higher intensity of geochemical transformations of rock and soils under the former and modern climatic conditions.
The geochemical characteristics of the fallow soils under the ancient vineyards at the near (cinnamonic soils) and distant (rendzina soils) chora of Chersonesos were largely determined by the differences in the contents of six macro-elements (Ca, Al, Fe, Si, Mg, P) and seven trace elements (Ni, Cu, Zn, Sr, Pb, Cr, V). If the cinnamonic soils of Chersonesos mostly accumulated Si, K, Fe, Al, P2O5, the grape soils of distant chora differed by the predominance of V, Pb, Rb, Cr.