1. Introduction
The current use of land and climate change have led to a dangerous degradation of the erosive land. According to various estimates, these negative processes have spread to almost 15 million hectares, and, together with the wind erosion – to 20-21 million hectares. Every year, on average, about 15-20 t ha
-1 of the fertile soil layer is lost, and the area of the eroded land increases to 100 thousand hectares. When the wind erosion and, especially, the dust storms occur, the soil losses reach 50-100 t ha
-1. The amount of humus, nitrogen, phosphorus and potassium, lost as a result of erosion, significantly exceeds their introduction with organic and mineral fertilizers. Therefore, dehumification and depletion of the soil fertility are observed, which negatively affects not only the yield of agricultural crops but also the ecological condition of agricultural landscapes [
1,
2,
3,
4].
In the greatest part of territories, the risks of erosive degradation, dehumification and depletion of fertility are increasing, associated with both changing the climate conditions and imperfect agricultural practices [
5].
Under the conditions of complex negative relief, the soil cover is particularly affected by such factors as rectangular organization of the agricultural lands, destruction of natural watercourses, deterioration of agrophysical properties of soils, sowing of the row crops on slopes >3°, destruction or deterioration of the forest belts and anti-erosion forest plantations, as well as suspension of state and regional programs for the protection of soils from erosive degradation. Along with the increase of temperature in the process of climate change in all natural and climatic zones over the past 30 years, there has been an increase in the torrential nature of precipitation, which, with an increase in the sown areas of such intensive crops as maize and sunflower, increases the risks of water and wind soil [
6,
7].
Consequently, the imperfection of agricultural practices and land management, as well as the underestimation of the impact of natural factors, in particular the climate change, increases the risks of intensified degradation of the agricultural lands, deterioration of the soil quality, and their ability to perform agroecological and biospheric functions in the agrosphere.
In the context of fairly rapid climate changes, intensification of agricultural production, high risks of degradation and desertification of agricultural lands, methods for the timely detection and identification of manifestations of degradation processes as a basic foundation for improving the land use systems and sustainable management of agricultural resources are becoming especially relevant.
At the present time in agricultural practice the main provision of the analysis of ecological and landscape conditions as a balanced relationship between the exploitation, conservation and improvement of the land fund of a specific type and kind of agricultural landscapes of a certain natural and climatic region is missed.
At the same time the development of aerospace survey technologies, automated methods for decoding satellite data and spatial simulation, using a geographic information system (GIS), make it possible to quickly identify and assess the risks of the soil degradation and monitor the ecological state of agricultural landscapes and land use systems [
8,
9,
10,
11,
12,
13,
14,
15,
16,
17,
18].
The real threat of global land degradation and, in general, the disruption of the sustainability of the biosphere has caused justified concern in the world community and led to an understanding of the need for concerted and coordinated actions by states and the general population at the interstate level to prevent land destruction and mitigate the effects of drought and degradation.
In several countries a significant information database has been accumulated that characterizes the intensity of soil erosion on slopes, the properties of eroded soils, the effectiveness of individual anti-erosion measures and their complexes [
19,
20,
21,
22,
23,
24].
These facts require increased attention to the study, control and overcoming of erosive degradation, in particular, establishing the scale of degradation processes, identifying current threat.
The problem of determining the role of factors that influence the reduction of the risk of the water erosion processes has been studied by scientists since the middle of the 19th century with the aim to forecast and develop a methods for combating erosion, taking into account the global, regional and local levels. The rate of soil erosion depends on a number of factors, such as the geomorphological features, the soil characteristics, the land using systems, and land management practices [
25,
26,
27,
28,
29,
30].
Over the past decades the factor of the land using system (land ratio) has acquired particular relevance in connection with the large-scale progression of the erosion processes, which are associated with the increase in the arable land, and which, wih time, lead to the loss of biodiversity, soil degradation, and deterioration of the environmental services [
30,
31].
Thus, the global scientific community faces the need to find ways to solve the problem of rationalizing land use.
The EU countries are pursuing an active land policy to create a balanced system of natural resource management. Thus in Great Britain a concept of a scale of landscape conservation has been developed with the aim to solve the issues of the climate change, and to restore biodiversity in the conditions of a complex landscape [
32].
In order to preserve and increase the biodiversity in the EU countries, a network of protected areas (Natura-2000) has been created. The elements of this network are types of natural environments (Special Areas of Conservation), rare and under threat of destruction [
32,
33].
Agricultural and management practices play an important role in the control of the soil erosion. For example, the rate of the soil loss decreases exponentially as the vegetation cover increases. The impact of the land usage and management is often parameterized in the covering management coefficient. The researchers propose a methodology for assessment of the covering management coefficient in the European Union (EU), using statistical data about agricultural crops and practices [
34,
35,
36].
The aim of the research is to determine the soil conservation capacity of technologies for creating a system of phytomeliorative measures (land conservation), to establish patterns of restoration of herbaceous phytocenoses on anthropogenically transformed lands in the system of soil conservation agriculture in the context of the risks of increased manifestations of water and wind erosions and determining ways to solve existing problems.
3. Results
The organization of rational use and protection of lands of sloping agricultural landscapes is a multifaceted problem that requires a comprehensive approach to solving pressing legal, economic and environmental issues under the current conditions of completion of the land reform. The solution to this problem is possible through the development of scientific paradigms with the definition of necessary measures to increase productivity, protection and rational use of erosion-degraded lands, ecological stabilization of agricultural landscapes, optimization of the structure of lands, conservation of degraded sloping lands, based on their environmentally safe use. Taking into account the environmental situation that has developed in the agricultural land use by the state, there is an urgent need to develop new approaches to improve the system of soil and water conservation measures and to develop new ways of rational use and protection of land with the aim of innovative development of highly efficient agricultural production, minimization and achievement of a neutral level of degassing processes.
This actualizes the need to conduct scientific research, aimed at obtaining new knowledge about the patterns of functioning of agricultural systems and their individual components for the creation of new scientific products, including through the development of environmental management systems and technologies for protecting soils from the manifestation of erosion processes in agricultural landscapes of Ukraine. This actualizes the need to conduct scientific research, aimed at obtaining new knowledge about the patterns of functioning of agricultural systems and their individual components for the creation of new scientific products, including through the development of environmental management systems and technologies for protecting soils from the manifestation of erosion processes in agricultural landscapes of Ukraine. Conservation (restoration) of herbaceous communities on former arable lands is a complex and dynamic process in time, consisting of a series of temporary, determinately chaotically changing stages of overgrowing, each of which is characterized by a unique ecological-biological, morphological, floristic-individualistic structure and a special state of biodiversity.
The scientific foundations for creating highly productive herbages of natural forage lands, rational use of cultivated hayfields and pastures have already been brought to the level of methodological developments and practical recommendations. However, ensuring an efficient organization of land areas when using a system of anti-erosion measures in soil-protective adaptive agriculture requires their more thorough study for the purpose of further application by the business entities.
The soil-water conservation and agroecological efficiency of methods for creating and operating highly productive herbages on the degraded natural forage lands and on the lands in erosion-hazardous zones of agricultural landscapes, removed from intensive cultivation, remain unclear, which indicates the relevance of these studies.
The theoretical and methodological basis for the study of ecological optimization of the agricultural landscape were fundamental ecological, geographical, historical, socio-economic concepts, hypotheses of domestic and foreign authors, concepts of land relations in modern agricultural production.
The analysis of the results of studies, conducted in Ukraine, has shown that the meadow lands will function harmoniously only when they simultaneously fully perform not only a forage production role but also a nature conservation role. As has already been noted, with an increase in the forage production value of the meadow lands, that is, their productivity or ecological capacity, their nature conservation role, that is, their soil protection capacity, also increases [
2,
3,
4,
5].
With the increase in the forage production value of the meadow lands, that is, their productivity or ecological capacity, their nature conservation role, that is, their soil-protective capacity or buffer capacity also increases. In comparison with the field lands, the meadow lands involve significantly more mineral and organic substances in the biological cycle and do not allow them to go beyond their boundaries. Situated in the transition zone of agricultural landscapes, they represent a buffer zone and a reliable barrier to the surface migration of silt particles of soil and agrochemicals from arable lands, which often occurs during heavy rains, due to their dense grass cover and buffer capacity. Due to this capacity, they reliably protect soils, located on the slopes, from erosion, and the water sources from siltation and pollution. Situated in the transition zone of agricultural landscapes, they represent a buffer zone and a reliable barrier to the surface migration of silt particles of soil and agrochemicals from arable lands, which often occurs during heavy rains, due to their dense grass cover and buffer capacity. Due to this capacity, they reliably protect the soils, located on slopes, from erosion, and the water sources from siltation and pollution.
In this respect, when solving the problems of soil protecting from erosion and improvement of the condition of agricultural territories, a landscape approach is promising, which necessitates a systemic analysis, taking into account many factors that influence the environmental optimization of the agricultural landscape [
11,
12].
The scientists from the Department of Agricultural Land Use and Soil Erosion Protection of the National Scientific Centre “Institute of Agriculture of the National Academy of Agrarian Sciences”, in cooperation with the scientists from the Ulbroka Scientific Centre of the Latvian University of Life Sciences and Technologies are conducting regional monitoring of the territory of agricultural land use in the Kyiv region by means of cartographic and field surveys of the state of land in order to assess the natural resource potential and environmental stability of land use. (
Figure 1).
In the study area, the rainfall erosion dominates over the meltwater erosion. High-intensity summer precipitation (up to 4 mm per minute) is observed, often falling in layers of more than 50 mm (
Figure 2).
Along with the highly dissected relief and deep (up to 60 m) erosion base, heavy rains are the main factor in the intensive development of the erosion processes (
Figure 3).
The main component of the soil conservation farming system is the implementation of a set of measures to optimize the structure of the land use of a specific farm by removing eroded arable and other low-productivity lands, located on slopes with an inclination of 3 degrees or more, from intensive cultivation, expanding the area of the forage lands and forest-covered lands.
When processing the methodological and methodical approaches to determine the directions of efficient use of phytomeliorative measures in the system of adaptive-landscape agriculture of the farm, typical research objects were selected - polygons, their geobotanical and land management field survey was carried out, the characteristics of the studied natural, social and anthropogenic factors within the element (polygons-tracts) were determined. The conducted scientific research is based on the methodology of landscape ecology, landscape science and applied methods of observation and determination by applying the methodological foundations of the land management field route, ecological-geographical and geomorphological studies and research, processing of cartographic materials and results, obtained in the field experiments. The results of the field landscape and landscape-geochemical studies and surveys, geobotanical descriptions of the investigated areas were used. Monitoring studies were conducted to study the dynamics of the species’ ecological and biological structure of spontaneously regenerating herbages in the process of their formation in six landscape-geochemical systems - tracts (polygons No. 1-3), and the geomorphological characteristics and condition of the studied polygons were determined. The scientific observations were performed through field route surveys and the land inventory.
The monitoring route studies were carried out at specific and recorded sites (polygons) on the ground (in nature), and on cartographic materials (polygons) at a scale of 1:10,000.
The area of the polygon 1 is 20 hectares. Slopes with the western, north western and southwestern exposures. The absolute maximum elevation of the earth’s surface is 177 meters, the minimum is 127 meters. The average length of the slopes is 149.1 meters, the steepness is 4.024% (
Figure 4).
Soils: typical chernozems and highly degraded chernozems, moderately eroded, light loamy. The slopes are blackened and covered with grassy vegetation. The plant groups – phytocenoses of the ravine slopes are rich in their diversity and density. There are about 300–400 plants per 1 m
2 (
Figure 5).
The species saturation of the phytocenosis at the site belongs to the 1st density class – (a plant community) – the plants, close with their above-ground upper parts and form a 100% projective cover, which has a positive effect on the protection of soils from their washout and flooding by heavy rainfall. In spring, during the snow melting, the developed root system and dead above-ground grass mass (natural mulch) prevent the erosion processes.
There are also found the grassy grass groups, mainly represented by the creeping wheatgrass (Elymus repen), occasionally by the bristle grasses (Setaria), and by feather grass (Stipa pennata L). The slopes are turfed, covered with dense herbaceous vegetation; there are single bushes of silverberry (Elaeagnus commutata). The plant groups – phytocenoses of the ravine slopes are rich in their diversity and density. There are from 300 to 500 plants per 1 m2. The phytocenoses of mixed grasses have a rich species composition of tall plants, in particular; some of them: musk thistle (Carduus nutans); common milkweed (Asclepias syriaca L.); Common yarrow (Achillea millefolium); St. John’s wort (Hypericum perforatum L.); Common tansy (Tanacetum vulgare L.); White cinquefoil (Potentilla alba L.); Scentless chamomile (Unscented chamomile); sea mayweed (Tripleurospermum maritimum); hoary alyssum (Berteroa incana L.) musk thistle (Carduus nutans); common milkweed (Asclepias syriaca L.); Common yarrow (Achillea millefolium); St. John’s wort (Hypericum perforatum L.); Common tansy (Tanacetum vulgare L.); White cinquefoil (Potentilla alba L.); Scentless chamomile (Unscented chamomile); sea mayweed (Tripleurospermum maritimum); hoary alyssum (Berteroa incana L.), musk thistle (Carduus nutans); common milkweed (Asclepias syriaca L.); Common Yarrow (Achillea millefolium); St. John’s wort (Hypericum perforatum L.); Common tansy (Tanacetum vulgare L.); White Cinquefoil (Potentilla alba L.); Sea Mayweed (Tripleurospermum maritimum); hoary alyssum (Berteroa incana L).
The polygon 2 area is 25 ha. The slopes with eastern and northern exposure. The absolute maximum elevation of the earth’s surface is 190 meters, the minimum is 130 meters. The average length of the slopes is 112.2 meters, the steepness of slopes is 7.125% (
Figure 6).
Soils: typical chernozems and highly degraded, highly eroded, light loamy chernozems. The slopes are turfed and covered with grassy vegetation. The plant groups – phytocenoses of the ravine slopes are rich in their diversity and density. There are up to 300 plants per 1 m
2 (
Figure 7).
The species saturation of the phytocenosis at the site is according to the Drude scale belongs to the 1st class of projective cover – the plants, close with their above-ground upper parts, forming 100% of the projective cover, which has a positive effect on the protection of the soils from their washout and flooding by rainfall.
In spring, during the melting of snow, the developed root system of perennial grasses and the dead above-ground grass mass (natural mulch) prevent the erosion processes.
The cereal grass groups are represented mainly by the creeping wheatgrass (Elymus repen), and occasionally by the bristle grasses (Setaria).
Phytocenoses of the mixed herbs have a rich species composition of tall plants, in particular, some of them: Common yarrow (Achillea millefolium); common St. John’s wort (Hypericum perforatum L.); field spurge (Euphorbia agraria); common tansy (Tanacetum vulgare L.); white cinquefoil (Potentilla alba L.); non-scented chamomile (non-scented tricostal); sea mayweed (Tripleurospermum maritimum); hoary alyssum (Berteroa incana L.); Common yarrow (Achillea millefolium); St. John’s wort (Hypericum perforatum L.); Euphorbia arvense (Euphorbia agraria); common tansy (Tanacetum vulgare L.); white cinquefoil (Potentilla alba L.); chamomile not fragrant (three-rib not odorous) sea mayweed (Tripleurospermum maritimum); hoary alyssum (Berteroa incana L). The grass cover is not mown and is not grazed by the livestock.
The area of the polygon 3 is 30 ha. The slopes with the eastern and north-eastern exposures. The absolute maximum marks of the earth’s surface are 170 meters, the minimum are 130 meters. The average length of slopes is 123.2 meters, the steepness of slopes is 6.49% (
Figure 8).
Soils: typical chernozems and degraded chernozems, heavily eroded, light loamy. The slopes are turfed and covered with grassy vegetation. Plant groups – phytocenoses of the ravine slopes are rich in their diversity and density. There are up to 300 plants per 1 m
2 (
Figure 9).
The species saturation of phytocenosis at the polygon belongs to Class 1 projective cover – (a plant community) – plants, close with their above-ground upper parts, forming a 100% projective cover, which has a positive effect upon the protection of soils from their washout and flooding by heavy rainfall. In spring, during the melting of snow, the developed root system of the perennial grasses and the dead above-ground grass mass (natural mulch) prevent the erosion processes. The grassy grass groups are occasionally represented by creeping wheatgrass (Elymus repen).
The phytocenoses of mixed herbs have a rich species composition of tall plants, in particular, some of them: Common milkweed (Asclepias syriaca L.); Common yarrow (Achillea millefolium); common St. John’s wort (Hypericum perforatum L.); Common mullein (bear’s ear) (Verbascum thapsus L.); Field spurge (Euphorbia agraria); Hoary alyssum (Berteroa incana L.).
By the conducted determinations and geobotanical descriptions it has been established that the spontaneously restored herbages were distinguished not only by the presence of a significant number of species and increased projective cover but also by a sufficiently high diversity of taxonomic structure, as one of the important indicators of the state and functional properties of phytodiversity of cenoses, the implementation of their adaptive and soil-protective self-regulation capabilities and the formation of stable grassy ecosystems.
In spontaneous restoration of herbage on strongly and moderately washed soils in the composition of vegetative vegetation groups, drooping brome (Anisanthus tectorum), creeping wheatgrass (Elymus repen), common milkweed (Asclepias syriaca), hoary alyssum (Berteroa incana), i.e. representatives of various grasses with the exception of creeping wheatgrass, prevailed.
It should also be noted that in the composition of the spontaneously regenerating herbage in a fairly wide spectrum were represented adventive (introduced) species, such as Cheatgrass (
Bromus tectorum), Common milkweed (
Asclepias syriaca), Bitter wormwood (Artemisia absinthium), Wild radish (
Raphanus raphanistrum), Annual fleabane (
Erigeron annuus) (
Figure 10).
Agrocenoses of perennial grasses to the greatest extent protect the washed-out soils of the slope agricultural landscapes from the active development of water erosion processes. At the same time the quantitative assessment of the soil conservation efficiency of perennial herbaceous agrocenoses reflects the multifactorial conditions of the formation of the erosion situation in a specifically designated territorial area (polygon).
There was carried out determination of the predicted soil losses as a result of water erosion within the territorial boundaries of the investigation sites No. 1-3. The soil losses were found out using the universal equation of erosive soil losses (Universal Soil Loss Equation – USLE):
where:
W – the calculated total soil loss per year t ha-1;
R – the rain erosive capacity factor;
K – the soil susceptibility factor to the erosion processes, t ha-1;
L – the slope length factor, m;
S – the slope steepness factor, %;
C – the vegetation and crop rotation factor;
H – the soil conservation practice factor (dimensionless).
The calculated quantitative indicators of the soil loss due to the water erosion at the investigated sites W – 2.38; 4.19; 3.88 t ha
-1 (
Table 1) with maximum allowed erosion rates for typical eroded chernozems 1.1 - 1.5 t ha
-1 indicate a very high anti-erosion efficiency of the soil protection (preservation) technologies from the soil loss and erosion. In addition, this makes it possible to judge about the comparative intensity of the erosion processes depending on the technologies for using the soil cover in erosion-hazardous agricultural landscapes, the methods and techniques for allocating land for conservation, and the development of management decisions in the design and implementation of the soil-protective agricultural systems (
Table 1).
Under the conditions of complex relief of the slope agro-landscape systems as a result of irrational human activity, a sufficiently high part of the energy, contained in the soil in the form of humus and nutrients, can be lost with washed-out soil beyond the agro-ecosystem, which leads not only to a decrease in its productivity but also affects its sustainable functioning. The eroded soils of the studied polygons are represented by medium and highly eroded typical chernozems, where the fertile soil layer is completely or 75-80% washed away, and in many cases the upper transitional horizon is also washed away. In this case the humus losses amount to 50-65% in highly eroded soils and 40-45% in moderately eroded soils.
The degree of erosion of typical chernozem soil in the investigated areas had a significant impact on the humus content in the 0-20 cm soil layer (
Table 2).
Thus, on the heavily eroded soil cover differences of polygons No. 2-3, the humus content indicators were 1.96–2.13%, with its initial values for the period of putting the slope lands into conservation being 1.75–1.98%. The moderately eroded typical chernozem, which, as a result of water erosion, has lost about one third of the upper genetic horizon with washout, with the humus content indicators corresponding to the average values (DSTU 4362:2004). The moderately eroded typical chernozem, which, as a result of the water erosion, has lost about one third of the upper genetic horizon with washout, with the humus content indicators corresponding to the average values (DSTU 4362:2004).
For the soils, formed on loess rocks, erosive losses of the surface genetic horizons lead to an increase in the content of the meadow and meadow-earth metals in the soil absorption complex, while the reaction of the soil solution (pH) approaches neutral values (7.1-7.3) (
Table 2).
The practice of applying land conservation measures shows that, in agroecological terms, this technology ensures a significant reduction in the soil loss during agricultural use of such lands as part of forage lands (hayfields, pastures) and contributes to an increase in the fertility of the washed-out soils, improving the ecological state of the environment, as a whole.
During the functioning of spontaneously restorative herbage changes in the mineral component of the soil conditions are observed, as a result of an increase in fractions and gross forms of phosphorus, fixed potassium and total nitrogen that are difficult for plants to access, that is, changes occur in the direction of gradual restoration of the basic components of the fertility of the degraded soils.