Monitoring the Properties of an Abandoned Depleted Peat Bog to Determine the Prospects for Use

Abstract

Peatlands after drainage can be effectively used as highly productive agricultural grasslands. The preservation of the fertility of peat soils depends on the nature of their use in agricultural production. Irrational and illogical use of peat bogs leads to loss of organic matter and nitrogen and reduction of their reserves. Currently, these deposits are often in the form of abandoned and overgrown forests. The appearance of disturbed landscapes leads to negative changes in vegetation and soil cover, water and temperature balance of the area, composition of soil, waste water and development of water, and wind erosion. The results of monitoring changes in some soil properties of a peat bog over a 20-year period are presented. The results of the geobotanical survey of the peat massif, which was conducted for the first time, are presented. The influence of the action of biotic and abiotic factors on the change of agrochemical characteristics of anthropogenic-transformed peat soil is determined. Depending on the degree of development, it can be used for forage land (cultivation of perennial grasses), on plots (maps) with sufficient reserves of lowland peat for these purposes after clearing channels and diverting excess water, except for the cultivation of perennial grasses; peat extraction for the production of organic fertilizers (compost) is possible.

1. Introduction

A peat bog is a complex ecosystem, the main components of which are water, vegetation, and peat. Experts consider the swamp as a group of interconnected biogeocenoses characterized by abundant moisture, specific moisture-loving vegetation, and peat formation [1]. The living conditions of plants here are different from the conditions of forests and meadows. Swamps are characterized by constant or periodic abundant moisture, insufficient aeration, poor nitrogen-mineral nutrition, and constant growth of peat substrate.

There are peat bogs and bogs in almost all natural areas. Grass bogs, for example, are found in all zones of the European part of Russia—from tundra to semi-deserts. Polygonal and bumpy swamps are common in the tundra, upper sphagnum swamps—in the coniferous forest (taiga) zone. The nature of the distribution of bogs, their size, configuration, species composition and structure of vegetation cover, the thickness, and structure of peat deposits are mainly due to climate and geomorphological conditions [1, 2].

The largest areas of peat bogs in the European part of Russia are concentrated in the north and northwest of the coniferous forest (taiga) zone. The dominant position is occupied by convex oligotrophic peatlands, for the development of which the most favorable conditions have been developed here: significant predominance of precipitation over evaporation, rather high relative humidity, proximity to the surface of groundwater and the lack of mineral nutrition in their elements; and flatness of the territory as well as a long history of the development of surface formations. This zone is characterized by intensive peat accumulation and makes up the bulk of Russia’s peat reserves [2].

Swamps are also important for maintaining the water level in adjacent biocenoses. Complete drainage of the swamp can ruin the nearby area. If the sea is close, seawater will invade the groundwater used as drinking water in cities located on the coast. Many small rivers, streams, and tributaries of large rivers originate in the upper marshes, and if the marshes are drained, the rivers will lose their sources feeding them. Even when swamps do not share water with rivers, they slow down the surface runoff of water falling to the ground in the form of precipitation, and this is very important, since water should flow down the ground as slowly as possible to prevent erosion. After the campaign to drain the swamps, which was carried out in the past century in the Soviet Union, peat bogs begin to burn every hot summer in the Central Federal District. The main reason for this was the violation of fragile hydrological cycles [3].

In recent years, the marshes have become the object of close attention of scientists. This is not surprising because swamps are not only unique ecological systems but also valuable mineral deposits. The development of swamps is very rapid. The discovery of the richest deposits of oil and gas in the wetlands of Siberia and the Far North, the development of peat, as well as the increase in the area of arable land, all this requires the drainage of swamps. At the same time, there is a threat of their complete destruction. But as a natural landscape, swamps are an integral part of the biosphere. As noted above, they play a major role in the hydrological balance of a number of localities. At the same time, many aspects of the functioning of swamp ecosystems remain unknown until now. Therefore, swamps as a type of plant community require not only comprehensive protection but also fundamental research. Such studies are especially relevant in Russia because in terms of the total area of wetlands, our country ranks first in the world [4].

The peat deposit with its ecologically useful resources is of interest for agricultural production. A peat bog after drainage (reclamation) can be effectively used as a highly productive agricultural land. Peat soils of lowland and transitional bogs surpass chernozems in terms of potential nutrient reserves in a meter layer and, with rational use, are much more productive than sod-podzolic and gray forest soils. As the research results have shown, the highest payback of fertilizers and low cost of high-quality products are achieved on cultivated peat bogs (Уланов).

The peat soils of fens and transitional mires on the potential reserves of nutrients in the m layer are superior to the black soil and the rational use of much more productive sod-podzolic and gray forest soils. Abandoned drained peatlands represent an environmental hazard in connection with a high likelihood of fires, the cause of which is mainly the failure to comply with fire safety in the temporary dry grass, kindling fires, etc. [5, 6].

Drained and abandoned peat bogs pose an environmental hazard due to the occurrence of peat fires, the cause of which is mainly non-compliance with fire safety when burning dry grass, kindling fires, etc. The long-term preservation of the fertility of peat bogs depends on the nature of their use. With incorrect methods of use, rapid mineralization of organic matter occurs, which leads to a reduction in its reserves. Mineralization of organic matter leads to unproductive loss of mobile forms of nitrogen compounds [7, 8].

Shallow-lying and shallow-contoured peat bogs (up to 10 hectares) should be allocated for cultural hayfields and pastures. When developing methods of intensification of agriculture on peat soils at different stages of anthropogenic evolution, an objective assessment of the state of properties and the forecast of their possible changes over time under the influence of anthropogenic and abiotic factors is of utmost importance. The introduction of agricultural land plots with small-contour peat deposits into circulation is of practical interest for land users, which is associated with the fact that these soils are potentially highly fertile and can be successfully used for growing fodder crops. But at the same time, such peat deposits have a feature that is associated both with the specifics of the use of peat soils and with their periodic water logging, since they are mainly located at the edge of the forest and at the edge of fields with mineral soils [9, 10, 11].

There are 9260 small-scale (up to 10 ha) peat deposits on the territory of the Russian Federation, which occupy an area of 108.6 thousand hectares in the zero boundary of the deposit [12]. The largest number of shallow-lying and shallow-contoured peat bogs is located in the North-Western, Central, and Volga Federal Districts. So, in the Central Federal District, out of 7287 explored deposits, 2390 are small scale and 1298 are small scale and protected, that is, almost half. On the territory of the Vladimir region, where these studies were conducted, out of 723 peat deposits, 421 are deposits with an area of 1 to 10 hectares, where proven peat reserves in the sum of categories A + B + C1 and C2 (144 deposits) and forecast resources in category P1 (277 deposits) amount to 4277 thousand tons. Small-contour peatlands are often located on the edges of fields with mineral soils and adjacent to forests; their use in agricultural production has its own characteristics and is associated with the characteristics of peat soils. Currently, such deposits are abandoned and overgrown with forests. The degradation of landscapes entails a deterioration in the quality of vegetation and soil cover, water and temperature balance of the peat reserve territory, and soil composition, which provokes the development of water and wind erosion. At the same time, there is a transformation of the forest-meadow agricultural landscape with the dominance of meadow plant species into post-swamp forest-shrub-grass-sedge landscapes with significant participation of secondary forest phytocenoses [10]. In addition to negative changes in vegetation cover and water and temperature balance of the territory, soil degradation develops. With illiterate and irrational exploitation of the peat bog, rapid mineralization of organic matter occurs, which leads to a reduction in its reserves and unproductive loss of nutrients.

Soil physical, chemical, and biological properties collectively determine the quality of the soil. The biological properties of the soil are characterized by the presence in them not only of various microorganisms but also of the processes of plant growth. Dying plants and their parts, deposited in the soil, are enriched with nutrients in forms resistant to leaching. The root system of plants moves minerals from the lower layers to the upper ones. The biological process is, thus, a factor in the concentration of nutrients in the soil. Both mineral salts and synthesized organic substances containing a lot of nitrogen are concentrated in the upper layer [7, 8].

Agrochemical surveys are carried out in order to obtain information about the content of plant nutrition elements in the soil and as a consequence of the level of its fertility. Agrochemical examination allows more rational use of fertilizers and to minimize their negative impact on the environment. As a result, agrochemical cartograms of the content of elements, agrochemical essays, and application maps of fertilizer application are created. We determine the basic properties of the soil, which in one way or another can affect the growth and development of plants. One of the most important indicators determined by agrochemical analysis is the reaction of the soil solution (pH), the content of mobile phosphorus and potassium required by plants [7, 8].

The importance of different plants in soil formation is not the same. Under the forest, if there are no herbaceous plants, organic substances do not accumulate. Due to the constant presence of fulvic acid here, salts are washed out of the upper layer, and the soil formed on the carbonate rock acquires an acid reaction (podzol formation process). Under herbaceous plants, due to their gradual death, organic residues are formed, which accumulate mainly in the thickness of the soil. The reaction of the soil solution here is more often neutral or close to neutral. Against this background, bacteria settle. Under the action of bacteria, the organic remains of plants turn into humus (humus), which gradually accumulates in the soil and improves it (the sod process) [7, 10].

The purpose of our study is to monitor changes and the state of agrochemical and other characteristics of anthropogenically transformed peat soils, depending on the directions of use of the developed peat bog to obtain data used to develop the most promising and rational ways of using the peat bog.

2. Monitoring the properties of an abandoned depleted peat bog

2.1 Materials and methods

The research was carried out at the Baigush peat deposit, located 1.5 km northeast of the village Baigushi (Sudogodsky district, Vladimir region, 56°078111 N, 40°493809E). This territory belongs to the middle peat-swamp region [2], the geomorphological conditions of which are represented by moraine and alluvial landscapes with the presence of pronounced traces of the last glaciation in the form of finite moraine formations that have undergone severe erosion. In 1943, the peat bog was assigned category C2 (assessed)—the field was intended for agricultural use. In 1963–1965, the massif was used for peat extraction for fertilizers. Until 1963, the thickness of the peat layer averaged 109 m⁻¹ (maximum 140 m⁻¹) and in 1975, no more than 40–50 m⁻¹ cm, so after 1975, the peat began to be used as hay or pasture. According to the Geological Survey of 1977, the type of peat deposits was defined as transitional, closer to lowland peat (A-15%, R-45%) [12]. The total area of the peat massif was 13.8 hectares and peat reserves—30 cubic meters (or 6 thousand tons at 40% humidity). Reclamation (drainage) was carried out in 1985; the drainage basin was a ravine.

From 1986 to 2014, the area of the peat bog was in the land use of the experimental production facilities of the Institute; on a small area of the peat bog (I and II peat charts), where the peat was almost completely worked and which was almost not flooded, grain and fodder crops were cultivated. On the remaining maps, peat was extracted for compost production; peat on maps III, IV, and V was partially worked. Currently, the territory of the peat bog is completely abandoned. In 1998, a soil-agrochemical survey of the territory of the peat massif was carried out; the layout of peat maps and conventional reference points are shown in Figure 1 and Table 1. Monitoring of changes in some agrochemical properties of the soil on peat charts of the Baigush peat deposit (Figure 1) was carried out 20 years after the first survey of the peat massif. The research was carried out by the route expedition method at the same survey points as in 1998 (Table 1).

Figure 1.

Layout of peat charts on the Baigush peat deposit: Sudogodsky district, Vladimir region, 56°078111 N, 40°493809E (used app “Google earth”).

V chart	Chart canal			Main canal
	*15*1	*14	*13
IV chart	Chart canal
	*10	*11	*12
III chart	Chart canal
	*9	*8	*7
II chart	Chart canal
	*6	*5	*4
I chart	Chart canal
	*1	*2	*3
Dirt road

Table 1.

Location of peat charts and survey points on the Baigush peat deposit.

In 2017–2018, to determine the change in the basic agrochemical properties of the fine-contour shallow peat bog, a soil-agrochemical and field geobotanical survey of the peat massif was carried out using the methods [13, 14, 15, 16].

Geobotanical description, determination of agrophysical, and biological properties of the soil by survey points were carried out for the first time in 2018. A geobotanical survey was carried out in biogeocenoses of 15 locations within the boundaries of five peat charts, which consisted of determining plant species and their abundance on the Drude scale [17]. Agrochemical parameters of the soil of the object were determined in accordance with state standards, nitrifying ability by the Kravkov method, cellulolytic activity by the application method, density, and density of the solid phase of the soil by the weight method.

2.2 Results and discussion

During the research, an expeditionary geobotanical survey of the peat massif was carried out, during which 80 plant species and their abundance were determined according to the Drude scale in biogeocenoses of 15 conditional reference points (locations) on five peat maps. At the moment, the geolocations of the points are fixed in the coordinate system. The vegetation cover of the surveyed territory is represented by meadow and forest phytocenoses. According to the results of the geobotanical survey of the object, the predominant types and types of vegetation were established (Figure 2).

Figure 2.

Vegetation types on peat charts.

On I chart, the composition of the herbaceous tier is diverse; the total projective cover degree (TPCD) of grasses is >70%: Veronica oakwood (Veronica vulgaris L.), ground vane (Calamagróstis epigéjos L.), bonfire without a tail (Bromopsis inermis L.), clovers, bluegrass, sharp sedge (Carex acuta L.), common tansy (Tonacetum vulgare L.), fine vole (Agrostis capillaris L.), creeping wheatgrass (Elytrigia repens L.), meadow timothy (Phlum pratense L.), common yarrow (Achillea millefolium L.), and horsetails. Shrubby vegetation type (TPCD >20%) is represented by shaggy willow (Salix lanata L.) and holly willow (Salix acutifolia L.) (Figure 3).

Figure 3.

Vegetation on the I chart.

On II chart, the proportion of herbaceous vegetation has decreased; the TPCD is >60%: field grass (Cirsium arvense L.), field cornflower (Centaurea jacea L.), common goldenrod (Solidago virgaurea L.), bonfire (B. inermis L.), clovers, bluegrass, acute sedge (C. acuta L.), sedge, thin vole (A. capillaris L.), creeping wheatgrass (E. repens L.), meadow timothy (Phlum pratense L.), and horsetails. The shrubby vegetation type (TPCD ~40%) is represented by shaggy willow (S. lanata L.), holly willow (S. acutifolia L.), and dog rose (Rosa canina L.) (Figure 4).

Figure 4.

Vegetation on the II chart.

On the territory of III–IV charts, shrubby vegetation type prevails, (TPCD >50%): shaggy willow (S. lanata L.), holly willow (S. acutifolia L.), and common hazel (Corylus avellana L.). Variegated grasses (TPCD ~25%) are replenished with moisture-loving vegetation: field grass (C. arvense L.), wood angelica (Angelica sylvestris L.), common goldenrod (Solidago virgaurea L.), clovers, bluegrass, forest cupyr (Anthriscus sylvestris L.), acute sedge (C. acuta L.), bubble sedge (Carex vesicaria L.), tenacious bedstraw (Galium aparine L.), vaginal fluff (Eriophorum vaginatum L.), and horsetails. The woody type of vegetation (TPCD ~25%) is mainly represented by rhombic alder (Ansys rhombifolia L.) and scots pine (Pinus sylvestris L.) (Figures 5 and 6).

Figure 5.

Vegetation on the III chart.

Figure 6.

Vegetation on the IV chart.

On the territory of V chart, the predominant vegetation type is woody (TPCD >50%): mainly it is hanging birch (Betula pendula L.), mountain ash (Sorbus aucuparia L.), and common pine (P. sylvestris L.). Shrubby vegetation type (TPCD ~25%) is represented mainly by shaggy willow (S. lanata L.) and holly willow (S. acutifolia L.). Motley grasses (TPCD ~25%): ground weiner (Calamagróstis epigéjos L.), bluegrass, sharp sedge (C. acuta L.), bubble sedge (C. vesicaria L.), tenacious bedstraw (G. aparine L.), vaginal fluff (E. vaginatum L.), horsetails, sod pike (Deschampsia cespitosa L.), and acute sitnik (Juncus acutus L.) (Figure 7).

Figure 7.

Vegetation on the V chart.

Thus, the overgrowth of the surface of the developed peat bog with woody-herbaceous vegetation largely depended on the capacity of the residual peat. On the plots that were completely and heavily processed (peat thickness from 0 to 50 cm) and retired from agricultural use in the mid-90s (point № 8, 9, 10, 15), a forest with its inherent tiering was formed: the bulk of woody vegetation is hanging birch (15–22 m), common mountain ash (2–4 m), and common pine (up to 3 m); shrubs are mainly represented by willows; the herbaceous vegetation is described in detail above (charts III–IV).

With the thickness of the residual peat layer of 70 cm or more, the growth and development of woody vegetation occurred slowly (point № 4, 7, 11, 12, 13, 14). The multi-tiered nature of the forest is poorly expressed: there are single birches (up to 5−6 m), aspens (2–3 m); shrubs are represented by willows, rose hips, and raspberries. Since these areas are under water until the end of spring, the herbaceous vegetation is mainly represented by moisture-loving plants: ground weinik (Calamagróstis epigéjos L.), swamp horsetail (Equisétum fluviatile), sharp (C. acuta L.) bubbly sedge (C. vesicaria L.), and fluff (Erióphorum vaginátum L.).

The data of the soil-agrochemical survey of a shallow-contour shallow-lying peat bog on 15 reference points, depending on the cultivation and intensity of the use of peat-boggy soils according to the maps, are presented in Table 2. As a result of observations, the change in the content of the main biogenic elements over a 20-year period (from 1998 to 2018) has been established. The content of mobile phosphorus and exchangeable potassium has changed to the greatest extent. So, on the I map, in the soil layer of 0–80 cm, the content of mobile phosphorus and exchangeable potassium changed slightly, which can be explained by the fact that the territory of the map was in agricultural use for a long time. The areas of the remaining charts have been abandoned for more than 20 years; in the spring, they are mostly under water; and in dry years, the territory of the II chart was partially used in the agricultural production.

Depth, сm	Content of mobile phosphorus (P2O5), mg/kg			Content of mobile potassium(K2O), mg/kg			рН
	1998	2017–2018	Δ	1998	2017–2018	Δ	1998	2017–2018	Δ
I chart
0–33	48.9	50.6	+1.7	45.7	39.2	−6.5	6.6	6.4	−0.2
33–80	10.1	12.8	+2.7	13.5	14.0	+0.5	6.4	6.35	−0.05
II chart
0–28	57.3	69.8	+12.4	69.7	62.4	−7.3	6.23	6.3	+0.07
28–80	27.3	35.9	+8.6	51.5	32.8	−18.3	4.7	4.9	+0.02
III chart
0–26	51.0	55.9	+4.9	62.3	61.2	−1.1	4.5	4.6	+0.1
26–80	15.0	17.4	+2.4	11.0	11.5	+0.5	30	3.5	+0.5
IV chart
0–34	15.9	27.1	+11.2	76.2	40.8	−35.4	4.5	4.4	−0.1
34–80	12.5	16.9	+4.4	64.0	20.0	−34.0	3.9	4.05	+0.15
V chart
0–35	17.4	42.8	+25.3	44.1	40.5	−3.6	3.9	3.9	0
35–80	11.5	24.3	+12.8	47.0	25.7	−21.3	3.3	3.6	+0.3

Table 2.

Changes in some agrochemical indicators over a 20-year period (average by charts).

On map V, an increase in the content of mobile phosphorus was found in soil layers from 0 to 80 m⁻¹, which can be explained in the absence of fertilizers by its biogenic accumulation, since phosphorus, as shown in the studies of T. Kulakovskaya et al., has an extremely weak migration ability, and no more than 3–5% of its total reserves is washed out [7, 8, 18, 19]. In addition, it was shown that in shallow, weak- and medium-azole peat bogs, with commercial water regime and high groundwater aquifer, they can penetrate into the subsoil and underlying layers [5, 6, 19], which our observations also showed. Unlike mobile phosphorus, an increase in the reserves of exchangeable potassium in the soil of maps IV–V in layers from 0 to 80 m⁻¹ was not observed, since its high mobility and intensive use are increasing, especially in the soil layer 30–50 m⁻¹, where the bulk of the roots are located. The pH values in the peat bog soil have not changed much.

The difference in the data on the biological and agrophysical properties of peat soil presented in Table 3 can be explained by the difference in the degree of cultivation of the studied soils and the residual peat layer on the charts. A direct relationship has been established between the thickness of the residual peat layer and the cellulolytic activity and porosity of the soil; an inverse relationship is established between the thickness of the peat layer and the nitrifying ability and density of the soil.

Peat chart	Point	Nitrification capacity, mg kg^−1 for 30 days	Cellulosol yical activity, %	Soil density (D), g m^−3	Poriness, %	The power of the residual peat layer, m^−1
I	1	31.0	17.0	1.8	39.0	<10
	2	32.4	17.5	1.40	39.5	<10
	3	32.8	17.5	1.49	26.2	<10
II	4	45.9	17.5	1.54	32.0	<10
	5	49.2	12.5	1.39	36.6	<10
	6	43.7	17.5	1.18	46.1	<10
III	7	14.8	70.0	0.68	65.4	31–50
	8	25.8	10.0	1.21	41.4	<30
	9	35.4	17.5	1.22	47.8	<30
IV	10	13.2	17.5	1.20	34.0	<30
	11	11.1	55.0	0.77	41.0	31–50
	12	11.9	57.5	0.77	59.0	>51
V	13	14.8	77.5	0.72	60.6	>51
	14	14.2	62.5	0.81	57.8	>51
	15	14.9	25.0	0.78	57.4	31–50

Table 3.

Biological and agro-physical soil properties peat.

The nitrifying ability of the upper soil layer decreases with increasing peat thickness (point № 7, 10–15), cellulolytic activity, and porosity; on the contrary, it increased at these points in the soil. With an increase in peat thickness, soil density indices decreased from 1,18-1,8 (point № 1-6, 8-10) to 0,68−0,81 g m⁻³.

3. Conclusion

During the soil-agrochemical survey of five peat bog maps, a change in the content of mobile phosphorus over a 20-year period was detected, which noticeably increased in the soil layer 0–80 m⁻¹ on the fifth map, and the content of exchangeable potassium significantly decreased in the soil on the fifth map and the fourth and fifth cards. During the monitoring of the condition of the developed fine-grained marsh peat, a direct relationship was established between the thickness of the residual peat layer on the maps and the cellulolytic activity and porosity of the soil as well as an inverse relationship between the thickness of the peat layer and the nitrifying ability, soil density. In depleted territories, vegetation is mainly represented by various grasses and shrubs, which can be explained by the rather long use of maps in agricultural production; in medium-developed territories, shrubby-woody vegetation prevails, with a peat layer thickness of more than 30 cm; and sedge and fluff dominate in flooded areas.