Natural properties of peat and the history of its scientific study
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Peat is an organogenic rock from the group of combustible mineral resources, formed as a result of the decay and incomplete decomposition of plants under conditions of excessive moisture and lack of oxygen. It is a complex natural formation—a multicomponent, polyfractional, semi-colloidal high-molecular-weight system containing various classes of organic and mineral compounds.
Elemental composition of peat: carbon 50–60%, hydrogen 5.0–6.6%, oxygen 30–40%, nitrogen 1–3%, phosphorus 0.1–0.25%, potassium 0.01–0.1%, sulfur 0.1–2.5% per combustible mass. The organic component composition includes water-soluble substances 1–5%, bitumen 2–10%, easily hydrolyzable compounds 20–40%, cellulose 4–10%, humic acids 15–50%, and lignin 5–20%. In its natural state, peat has a humidity of 86–95%. It is characterized by porosity of up to 96–97% and a high coefficient of compressibility during compression tests. The texture of peat is homogeneous, sometimes layered; the structure is usually fibrous or plastic. The color ranges from yellow or brown to black.
The first information about peat as "combustible earth" for heating food dates back to 46 AD and is found in the works of Pliny the Elder. In the Middle Ages, peat was known as fuel in Holland and Scotland. In 1658, the world's first book on peat, "Treatise on Peat" by Martin Schook, was published in Latin in the city of Groningen. Numerous misconceptions about the origin of peat were refuted in 1729 by J. Degner. Using a microscope to study it, he proved the plant origin of peat. In Russia, information about peat and its use first appeared in the 18th century in the works of M.V. Lomonosov, I.G. Lehmann, F.F. Zuev, and V.M. Severgin. In the 19th century, the works of V.V. Dokuchaev, G.I. Tanfiliev, and S.G. Navashin were devoted to peat. In Russia, studies of the nature of peat were botanical in character. Later, through the works of V.N. Sukachev, S.N. Tyuremnov, E.A. Galkina, D.A. Gerasimov, V.E. Rakovskaya, E.K. Ivanov, and other Soviet scientists, geographical patterns of peat deposit distribution were identified, a classification of peat types and peat deposits was created, cadastres and maps of peat deposits were compiled, and chemical composition and physical properties were studied.
In earlier periods of the Earth's history, peat formed in swamps represented the first stage of coalification. Without oxygen access and at low pH values, bacterial decomposition of dead plant parts is hindered, and the process of coalification begins, leading to the formation of peat. In modern times, peat is found in swampy areas in the form of layers up to several meters thick, which grow at a rate of approximately 1 mm per year.
World peat reserves are estimated at 285.4 billion tons. The Russian Federation ranks first in the world in peat reserves. According to geological records, the estimated peat reserves in our country are about 200 billion tons, of which 155 billion tons have been identified and explored. The main part of peat reserves is located in Siberia and the Far East, and only one quarter is in the European part of Russia (Table 117; Khokhlov V.I., 1988).
Table 117 – Arable land supply with peat reserves in the Russian Federation Distribution by main regions, % Peat reserves Economic region per 1 ha of arable land, thousand tons peat reserves arable land
North-Western 13.1 2.7 6.28 Central 3.4 12.7 0.35 Volga-Vyatka 1.3 6.6 0.25 Central Black Earth 0.1 9.4 0.01 Volga 0.2 25.7 0.01 Ural 6.2 15.3 0.52 West Siberian 68.7 16.9 5.26 East Siberian 3.2 7.9 0.52 Far Eastern 3.6 2.5 1.86 Kaliningrad Region 0.2 0.3 0.86
The classification of peat is based on a genetic principle, which states that a phytocenosis forms a corresponding type of peat. Depending on the composition of peat-forming plants and conditions of peat formation, peatlands, and consequently peat, are divided into three types: low-lying (eutrophic), raised (oligotrophic), and transitional (mesotrophic).
Due to the diversity of geographical conditions of peat accumulation, there are large differences in the qualitative and quantitative characteristics of peat deposits (Table 118; Khokhlov V.I., 1988).
Table 118 – Peat reserves by type of deposit, billion tons Peat Economic region raised transitional low-lying mixed total
Russian Federation 81731.9 23415.8 44697.8 4738.1 154583.6 Non-Chernozem zone 15951.6 5409.1 13179.2 1474.3 36014.2 North-Western 10943.2 3105.3 5091.9 832.4 19972.8 Central 1884.4 334.5 2505.5 239.1 4963.5 Volga-Vyatka 417.4 147.5 1183.8 109.3 1858.0 Central Black Earth 0.4 3.2 131.6 <0.1 135.2 Volga 9.6 3.5 319.2 0.6 332.9 Ural 2634.9 1826.4 4422.2 275.4 9158.9 West Siberian 63034.4 15224.0 26530.4 2985.3 107774.1 East Siberian 2225.1 714.0 779.4 254.4 3972.9 Far Eastern 488.3 2047.7 3544.7 23.0 6103.7 Kaliningrad Region 94.2 9.7 189.1 18.6 311.6
Raised peat deposits are located in elevated areas of watersheds and streams. Plants here are supplied with atmospheric moisture containing a very low content of dissolved salts. Raised deposits are covered with sphagnum moss, on which plants undemanding to mineral nutrition elements develop: cottongrass, cranberry, Scheuchzeria, wild rosemary, bog-rosemary, stunted pine, and birch on the edges. The ash content of raised peat is very low, and the acidity is high (Table 119; Gorodniy N.M., 1990).
Table 119 – Average content of ash elements and nitrogen in various types of peat, % of absolute dry matter Type of peat Ash 2O 5 K2O N Al2O3 Fe2O3 pH
Upland 2.0 0.30 0.12 0.06 0.08 0.8-1.2 0.30 0.15 2.8-3.5 Transitional 4.0 0.80 0.20 0.09 0.10 1.0-2.3 0.70 0.70 3.5-4.7 Lowland 6.5 2.50 0.30 0.10 0.12 2.3-3.3 0.70 1.30 4.7-5.5
Upland peat is characterized by a high content of organic matter, but a low degree of its mineralization; it has a high absorption capacity – 1 kg of dry peat can absorb 8-15 l of water. It is advisable to use poorly decomposed upland peat as bedding material and for preparing peat-liquid manure composts.
Lowland peat deposits are formed in low-lying relief areas: in river floodplains, near-terrace parts, or watershed depressions under conditions of moisture from atmospheric precipitation and surface and groundwater rich in mineral salts. Lowland peat is formed from sphagnum mosses, herbaceous (sedge, reed, cane, horsetail), and woody (alder, birch, spruce, pine, willow) plants. Since moisture-loving plants involved in the formation of this type of peat are demanding regarding elements of mineral nutrition, lowland peat contains many ash elements. It has less organic matter, but a higher degree of decomposition. The absorption capacity of lowland peat is lower than that of upland peat. Lowland peat is used mainly for composting.
Transitional peat deposits are intermediate; depending on nutrition conditions, they approach either upland or lowland types. In them, layers of lowland peat lie deeper, while upland peat lies above. Upland peat is used for preparing composts and as bedding for livestock animals.
Subtypes are distinguished within peat types: 1) forest; 2) forest-bog; 3) bog. Peat of different subtypes differs in the degree of decomposition.
The degree of decomposition of peat organic matter ranges from 1–5 to 50–60%. Here, a degree of decomposition of up to 20% is generally considered low, from 20 to 40% as medium, and above 40% as high. The degree of decomposition can be determined purely morphologically or quantitatively based on the ratio between decomposed material and plant remains that have preserved their structure. In field conditions, it can be determined by eye using the data in Table 120 (Vasiliev V.A., Filippova N.V., 1988).
The physical and agrochemical properties of peat depend on its degree of decomposition. The lower it is, the higher the air permeability, water capacity, buffer capacity, and water- and gas-absorbing capacity of the peat. The degree of peat decomposition can also be determined by its humification index (PHI), which is calculated by multiplying the content of humic acids in peat
0.001% (HAC, %) by their optical density index E 4.65:
PHI C hac E 0.001%
Table 120– Organoleptic signs of the degree of peat decomposition Degree of decomposition, % Main signs of peat condition
Less than 15 (undecomposed) The peat mass cannot be squeezed between the fingers. The surface of the compressed peat is rough due to plant remains, which are clearly distinguishable. Water is squeezed out in a stream, like from a sponge, clear and light 15–20 (very weakly decomposed) Water is squeezed out in frequent drops, almost forming a stream, slightly yellowish 20–25 (weakly decomposed) Water is squeezed out in a large quantity, yellow in color, plant remains are less noticeable 25–35 (moderately decomposed) The peat mass is almost impossible to squeeze in the hand, plant remains are noticeable; water is squeezed out in frequent light brown drops, peat slightly stains hands 35–45 (well decomposed) The peat mass is squeezed with difficulty. Water is released in rare brown drops 45–55 (strongly decomposed) The peat mass is squeezed between the fingers, staining the hand. Only some plant remains are noticeable in the peat. Water is squeezed out in a small quantity, dark brown in color More than 55 (very strongly decomposed) Peat is squeezed between the fingers in the form of a mud-like black mass. Water is not squeezed out. Plant remains are completely indistinguishable.Corresponding to this index, the degree of peat humification can be expressed as: 1) very low <0.5; 2) low 0.5–1.5; 3) medium 1.6–2.5; 4) high 2.6–3.5; 5) very high >3.5.
Forest subtype peat has a high degree of decomposition, bog peat has the minimum degree of decomposition; forest-bog peat occupies an intermediate position. Peat subtypes are divided into 4–8 species (Table 121; Kopenkina N.A., Neishtadt M.I., Chistyakov V.I., 1977).
A species is the primary taxonomic unit of peat classification. It reflects the initial plant grouping and the primary conditions of peat formation, characterized by a specific combination of dominant remains of individual plant species.
Botanical composition is one of the main indicators determining the quality of peat for agricultural use. Based on peat-forming plants, one can determine under what conditions of water and ash nutrition the peatland was formed. The botanical composition of peat is determined using a microscope at 80–100x magnification. Based on the nature of the cellular composition of plant remains and some other signs, the plants that participated in the formation of the peat are identified, and the percentage ratio of various remains is established.
Based on botanical composition, there are about 40 types of peat. However, not all types differ sharply from each other in their main properties, and therefore, for practical purposes, it is generally sufficient to distinguish three groups of peat: moss, herbaceous, and woody. Some types of peat can be identified by external characteristics, the description of which is provided in Table 122 (Vasiliev V.A., Filippova N.V., 1988).
Table 121 – Classification of peat types Forest Forest-marsh subtype Marsh subtype subtype Peat type woody- woody- herbaceous- peat woody herbaceous moss herbaceous moss moss group group group group group group
Peat groups and identification of its types by external characteristics
Peat is classified according to its formation conditions and origin into three main types: low-moor, transitional, and high-moor. Within each type, groups and types are distinguished depending on the prevailing plant residues. A specific type of peat can be identified directly in the field by its structure, color, and remaining plant parts. Depending on the site conditions, peat is divided into the following types and groups:
- Low-moor: alder, birch, spruce, low-moor pine, low-moor willow, woody-sedge, woody-reed, woody-hypnum, low-moor sedge, low-moor reed, sedge-hypnum, low-moor sedge-sphagnum, low-moor hypnum, low-moor sphagnum, bogbean, low-moor scheuchzeria.
- Transitional: transitional woody, transitional woody-sedge, transitional woody-sphagnum, transitional sedge, transitional sedge-sphagnum, transitional sedge-hypnum, transitional hypnum, transitional sphagnum, transitional scheuchzeria.
- High-moor: high-moor pine, pine-cottongrass, pine-sphagnum, high-moor cottongrass, cottongrass-sphagnum, scheuchzeria-sphagnum, medium-peat, fuscum-peat, complex high-moor, sphagnum-hollow.
To accurately identify the type of peat on-site, rely on its external features. In field conditions, the preservation of plant residues, the character of the structure, and color change upon exposure to air are of key importance. Detailed guidelines for rapid assessment are provided in the table below:
| Peat type | Peat variety | Characteristic features of visible plant residues | Peat structure, color, and change in air |
|---|---|---|---|
| High-moor | Sphagnum | Residues of sphagnum mosses in the form of thin, egg-shaped or elongated leaves (no more than 4 mm long, no more than 2 mm thick). Stems are cord-like, brown or pale in color. | Loose, spongy, or straw-like. Color from straw-yellow to reddish-brown. Darkens slowly, retaining its shade. |
| Cottongrass | Residues of cottongrass, appearing in dense strands, are clearly visible on the break. | Fibrous. Color is dark brown, darkens in air. | |
| Low-moor | Hypnum | Residues of hypnum mosses in the form of dark, thin (up to 1–1.5 mm wide) leafy stems. Leaves are of various shapes, often with a reflexed tip. | Loose-spongy. Fresh peat has a golden-bronze color, which quickly turns gray in air. |
| Reed | Greenish, fine hair-like roots of reed and coarse, rigid, greenish, ribbon-like rhizome plates 10–15 mm wide with clearly visible nodes. | Fibrous. Greenish color, darkens in air, but the shade remains. | |
| Woody | Coarse, rigid, or soft pieces of wood of various sizes are visible to the eye and palpable in the dense mass of peat. | Cloddy-granular. Color from dark gray (almost black) to brown, darkens in air. |
Agrochemical indicators and rules for peat preparation
The quality of peat as a fertilizer or bedding is determined by its physical and chemical properties: humidity, degree of decomposition, water capacity, exchange capacity, acidity, ash content, and chemical composition. Before using peat on a farm, its humidity must be brought to an optimal level of 50–60 %. The natural humidity of peat depends on the type of deposit and its drainage degree:
| Peat type | Humidity in natural deposit, % | Humidity in drained deposit, % |
|---|---|---|
| High-moor | 92–96 | 80–86 |
| Low-moor | 87–90 | 80–86 |
Highly decomposed peat must not be dried to a humidity of less than 40 %. In this state, it loses its ability to absorb water and swell. When applied to the soil, overdried peat does not decompose for a long time, does not show fertilizing properties, and in dry years it can even suppress crops.
Slightly decomposed peat, on the contrary, can be dried to 40 % and below, as it retains its ability to absorb moisture well after drying. The degree of decomposition determines the physical and agrochemical properties of the raw material. The lower it is, the higher the air permeability, water capacity, buffering, as well as the moisture and gas absorption capacity of the peat.
The exchange capacity characterizes the adsorption properties of peat and indicates its suitability as a fertilizer. For high-moor peat, this indicator is almost independent of the degree of decomposition, while for low-moor peat, it increases as decomposition progresses. Transitional peat is close to high-moor peat in terms of absorption capacity.
Slightly decomposed sphagnum peat is the best material for bedding and preparing composts. Due to the preservation of its plant fiber structure, it possesses maximum water-holding capacity, which is virtually unmatched among other types of peat.
Full water-holding capacity demonstrates the ability of raw material to retain water through molecular and capillary forces under conditions of free filtration. This indicator is directly related to the degree of peat decomposition. As the structure of plant remains breaks down, the ability to retain water naturally decreases.
- Total absorption capacity — 120–230 mg-eq per 100 g of dry peat
- Absorption capacity of sphagnum peat — 125–152 mg-eq per 100 g of dry peat
- Absorption capacity of fen peat — 147–230 mg-eq per 100 g of dry peat
- Natural water-holding capacity of the deposit — 500–3000 %
- Maximum water-holding capacity of sphagnum peat — up to 3000 %
- Water absorption of 1 kg of absolutely dry peat — from 5 to 30 l of water
Agrochemical profile of peat: ash content, acidity, and nitrogen forms
The effectiveness of peat in fields depends on its ash content — the percentage ratio of the residue after calcination to the total mass of the sample. High-ash deposits are formed due to the active inflow of mineral substances from surrounding dry lands or along with groundwater. Most often, such high mineralization is characteristic of fen peat.
During secondary salinization or active inflow of mineral substances by groundwater, specific types of peat deposits are formed:
- sandy;
- clay;
- calcareous;
- ochreous;
- vivianite;
- sulfurous.
It is generally accepted to consider an ash content of 50% of dry matter as the conventional boundary between peat and organomineral deposits. It is necessary in practice to precisely determine the type of peat, as the natural acidity of the raw material and calcium content depend on it. These parameters directly affect the suitability of peat for specific technological tasks.
- Ash content of sphagnum peat — 2–4%
- Ash content of transitional peat — 4–6%
- Ash content of fen peat — 6–18%
| Type of peat | pH | Calcium, % |
|---|---|---|
| Sphagnum | 2.6–3.2 | up to 0.25–0.35 |
| Transitional | 3.4–4.2 | up to 1 |
| Fen | 4.8–5.6 | up to 4 |
Peat has an acidic reaction caused by the presence of free organic acids and mobile aluminum. Fen peat is distinguished by reduced acidity due to the presence of calcium, whereas sphagnum peat, due to a calcium deficiency, is the most acidic. To neutralize excess acidity of peat raw material, agronomists use special ameliorating materials.
The following materials are used to neutralize peat acidity:
- lime;
- phosphorite flour;
- organic fertilizers (manure, liquid manure, feces).
Aerating peat eliminates the harmful effect of ferrous iron and aluminum compounds. By combining with atmospheric oxygen, they oxidize and lose their toxic properties.
An important characteristic of peat raw material is the total nitrogen content. In the organic mass of sphagnum peat, its quantity averages 1.5% (a range from 0.6 to 2.5%), and in fen peat — 2.6% (a range from 1.3 to 3.8%). Transitional peat occupies an intermediate position according to this indicator.
| Type of peat | Ammonium nitrogen, % | Amide nitrogen, % | Nitrate nitrogen, % | Amine nitrogen, % | Total readily available forms, % of total nitrogen | Protein and humic nitrogen, % of total nitrogen |
|---|---|---|---|---|---|---|
| Fen | 1.7 | 4.0 | 2.3 | 0.1 | 8.1 | 91.9 |
| Transitional | 4.5 | 1.7 | 1.6 | 0.3 | 8.1 | 91.9 |
| Sphagnum | 14.1 | 5.3 | 5.8 | 1.1 | 26.3 | 73.7 |
Most nitrogen compounds in peat are locked within complex organic substances — humic acids, proteins, lignin, and bitumen. In this form, nitrogen is unavailable for crop nutrition. This element converts into available forms only after prolonged mineralization during composting or using peat for bedding in livestock farming.
Biological characteristics of peat and its extraction technology
Peat mass possesses high biochemical stability compared to ordinary plant litter. This property is explained by the presence of humic acids, which are broken down extremely slowly by microorganisms. Products of microflora activity, which have distinct antibiotic properties, also accumulate in the peat-forming layer. Thanks to this, even carbohydrates easily accessible to microbes are preserved in peat.
Almost all groups of microorganisms involved in the decomposition of organic matter are present in peat mass. The only exceptions are nitrifying bacteria and Azotobacter, which do not survive in the natural conditions of the deposit. Fen peat is the richest in microflora, whereas sphagnum peat is highly depleted due to high acidity. At the same time, peat is completely safe for planting as it does not contain plant-pathogenic microorganisms.
Aerating peat leads to an increase in the number of almost all types of microorganisms. The only exceptions are cellulose-decomposing microorganisms, denitrifiers, and fungi.
The development of any peat deposit is preceded by its mandatory drainage. Also, all woody vegetation is completely removed from the surface of the future site. Peat extraction for fertilizer is carried out using a layer-by-surface method — milling or scraper-bulldozer.
- Milling of the top layer of the deposit with milling drums.
- Turning and drying of the milled layer.
- Windrowing of the dried layer.
- Harvesting peat from windrows.
- Stacking of the finished product.
Peat as fertilizer and ameliorant: application rules
Peat is a valuable component for enriching fields with organic matter, but using it in its pure form is inefficient. Due to the high stability of organic matter, nitrogen in the soil mineralizes extremely slowly, and the acidic reaction of the medium inhibits the development of beneficial microorganisms. The best result is obtained by preparing composts (manure-peat, peat-slurry, peat-fecal, and peat-vegetative) and mixtures with mineral fertilizers (ammonium-peat and mineral-ammonium-peat).
Applying pure peat as nitrogen fertilizer is not economically justified. Exceptions include highly decomposed low-lying peat with high ash content and a neutral reaction, provided it is transported from a nearby source, as well as peat tuff and vivianite peat.
Before applying pure peat to the soil, it must be prepared; otherwise, it will not provide any benefit to plants. The technology for preparing the raw material includes the following mandatory steps:
- Thoroughly grind the peat mass before use.
- Keep the ground peat in piles for at least 2–3 months.
- Wait for the weathering of compounds harmful to plants, and only then apply it to the fields.
Natural varieties of peat rich in phosphorus and lime are of particular value. Peat with a phosphorus content of at least 2% in the form of vivianite (iron phosphate) is used as a full-fledged phosphorus fertilizer. Vivianite inclusions are found in low-lying peat at a depth of 0.3–0.5 m in the form of white-gray streaks, which oxidize in the air and turn bright blue. In its pure form, vivianite contains about 28% phosphorus.
Peat with a lime content of more than 8% (in the form of white-yellow or grayish lumps) is used on acidic soils as a calcium fertilizer. Peat tuff with a CaO content of more than 10% works more effectively than ordinary lime. Its organic substances not only enrich the soil with nutrients but also increase its buffering properties.
To cultivate acidic podzolic soils, peat acts as an ameliorant. The application of large volumes of organic matter improves the physical and physicochemical properties of the arable horizon. The bulk density in the soil decreases, buffering increases, and an optimal background is created for the effective action of mineral fertilizers.
- Application rate of ameliorant — 500 t/ha
- Maximum peat humidity — 60%
- Type of peat for reclamation — predominantly low-lying
Peat in livestock farming and landscaping: bedding, mulch, and lawns
In livestock farming, upland peat with a decomposition degree of up to 15% serves as an ideal bedding. Due to its low thermal conductivity and high moisture capacity, it maintains warmth in the farm and absorbs moisture excellently. Sphagnum peat also inhibits the reproduction of pathogenic microorganisms in manure. The resulting manure retains more total and mobile nitrogen, and its losses during storage are reduced compared to straw bedding. The daily consumption rate is calculated individually based on the species and age of the livestock animals, as well as the quality of the raw material.
Monitor the fractional composition of the bedding. An excess of dust-like particles harms animals by clogging respiratory tracts and contaminating the skin, while oversized non-conforming chunks reduce the hygiene and quality of the farm's marketable products.
The quality of peat raw materials for bedding preparation is regulated by two categories:
| Quality indicator | Category I | Category II |
|---|---|---|
| Type and group of peat | Upland type, moss group | Any type; moss, grass-moss, and grass groups |
| Decomposition degree, % | up to 15 | Upland and transitional: 16–25 Low-lying: up to 15 |
| Ash content, % | up to 5 | Upland and transitional: up to 8 Low-lying: up to 10 |
| Cotton grass residue content, % | up to 5 | up to 15 |
Additional technological requirements are imposed on bedding peat. Its humidity should be in the range of 40–50%, and the content of woody residues should not exceed 10%. When these conditions are met, a high-quality bedding material with a minimal amount of dust is obtained.
Low-decomposed peat is also used in creating lawns and protecting soils from erosion. To grow peat-sod mats used for reinforcing the slopes of canals, water bodies, and embankments in temperate climates, drained deposits of upland peat are used. The raw material for such mats should have a decomposition degree of no more than 15%, an acidity of no more than 3, an ash content of no more than 20%, and a cotton grass residue content of no more than 15%.
Mulching with peat protects plantings from adverse external factors. The peat layer prevents the formation of a soil crust, reduces moisture evaporation, and saves winter crops from freezing. Due to low thermal conductivity, the mulch releases heat slowly, which effectively smooths out daily temperature fluctuations in the root zone.
Application of peat in greenhouses and neutralization rates
During the decomposition of peat, carbon dioxide is actively released, which stimulates photosynthesis and accelerates the accumulation of organic matter by plants. For mulching, well-decomposed, aerated peat with a humidity of up to 50–65% is used. It is spread in the inter-rows in a layer of 5–7 cm, and after harvesting the crop or when working on the tree-trunk circles of perennial plantings, it is incorporated into the soil.
When ploughing in peat, be sure to add a small amount of manure, liquid manure, or fecal matter. This will activate soil microflora and accelerate the decomposition of organic matter.
In greenhouse, milled peat serves as the basis for the production of specialized greenhouse substrates. In industrial vegetable production, three types of ready-made peat-based soils are used:
- Limed — peat neutralized with liming materials.
- Greenhouse/hotbed — peat neutralized with lime and enriched with phosphorus and potassium fertilizers.
- Biologically active — neutralized peat with the addition of phosphorus-potassium fertilizers and a mother culture of autochthonous microflora B.
The amount of lime for neutralizing excess acidity is calculated based on the initial pH level of the peat raw material. The application rates of the soil amendment per 1 tonne of peat with a standard humidity of 55% are given in the table. Additionally, 7 kg of superphosphate and 2 kg of potassium sulfate are added to each tonne of peat.
| Initial acidity of peat, pH | Lime consumption per 1 t of peat (at 55% humidity), kg |
|---|---|
| 2.5–3.0 | 40–45 |
| 3.0–3.5 | 35–40 |
| 4.0–4.5 | 25–30 |
| 4.5–5.0 | 20–25 |
| 5.0–5.5 | 15–20 |
| 5.5–6.0 | 10–15 |
Ready-made peat substrates: slabs and blocks
To optimize greenhouse production and the growing of transplants, ready-made industrial products based on raised-bog peat are used. The quality characteristics of these substrates are strictly standardized.
| Product type | Type of peat | Degree of decomposition, % | Ash content, % | Humidity, % | Acidity, pH KCl |
|---|---|---|---|---|---|
| Soils | Raised and transitional | not regulated | ≤ 25 | ≤ 20 | 50–60 |
| Peat-sod mats | Raised | ≤ 15 | ≤ 20 | 65–85 | ≤ 3.0 |
| Hollow peat pots | Raised, moss group | not regulated | ≤ 15 | ≤ 8 | ≤ 55 |
| Peat nutrient briquettes | Raised, sphagnum medium or fuscum | ≤ 8 | ≤ 8 | ≤ 53 | 2.5–3.5 |
| Compressed peat nutrient soil "Fialka" | Raised, moss group | not regulated | ≤ 15 | ≤ 12 | ≤ 55 |
| Substrate peat blocks | Raised, sphagnum mosses ≥ 70% | not regulated | not regulated | not regulated | not regulated |
| Micro-hotbeds | Raised, sphagnum, moss group | ≤ 15 | ≤ 15 | ≤ 60 | not regulated |
Dry-pressed slabs are manufactured in factory conditions from poorly decomposed raised-bog peat, enriched with macro-, meso-, and microelements. They have the shape of a rectangular parallelepiped with rounded corners and are intended for growing transplants, flowers, and vegetable crops.
- Slab dimensions — 290×290×50 mm
- Mass of one slab — at least 2 kg
- Humidity upon delivery — 17–30%
- Substrate acidity — pH 5.0–5.8
- Water-holding capacity — 5 kg of water per 1 kg of dry peat
Preparation of the slabs for use is carried out immediately before planting according to the following scheme:
- Level the beds in the greenhouse and cover them with polyethylene film.
- Lay out the dry-pressed slabs, leaving technological gaps of 5 cm between them.
- Evenly moisten the slabs by sprinkling from a hose through a fine-dispersion sprayer until fully saturated with moisture.
The use of compressed slabs solves several logistical and phytosanitary tasks at once. They are not prone to self-heating or spontaneous combustion during storage, require less warehouse space, and reduce transport costs. The absence of pathogenic microflora in the slabs protects the plant root system from diseases and allows for a transition to modern container growing methods.
Substrate peat blocks are porous hydrophilic slabs 4 to 5.5 cm thick, consisting of individual cells with depressions in the center. The cells are separated by incised or stamped grooves. The blocks are produced from limed raised-bog peat of a low degree of decomposition (up to 18%) with a pH of 2.9–3.0. The substrate contains 70–80% sphagnum mosses, no more than 0.7% chlorine, and no more than 1% iron oxide.
Industry produces peat blocks of the following sizes:
- cells: 100×100 mm and 50×50 mm;
- slabs: 500×500 mm, 1000×500 mm, and 20×500 mm.
The blocks are used for growing transplants of vegetables, flowers, ornamental, berry, and forest crops, as well as for creating portable lawns. Neutralized (limed) blocks and complex substrate blocks containing a full set of nutrients are available for sale.
The use of peat blocks eliminates labor-intensive operations: mixing soil, filling pots, and setting up trays. The porous structure of the blocks maintains strength during irrigation, which allows for transplanting plants with a root ball without damaging the roots.
Technology for using peat substrates, blocks, and pots
Compressed peat products make it possible to isolate the plant root system from the greenhouse soil, protect it from pathogens, and minimize trauma during transplanting. However, the efficiency of their application directly depends on compliance with the rules for layout and irrigation.
Peat blocks must be laid strictly on a leveled horizontal surface. Differences in height will lead to uneven distribution of moisture: some blocks will become over-moistened, while others will remain dry. Be sure to use a polyethylene film backing. It will block the roots from accessing the underlying soil, exclude the leaching of nutrients, and ensure reliable phytosanitary isolation.
- Block mass when fully saturated — increases by 7–8 times
Preparation of peat blocks for planting is carried out in the following sequence:
- Lay the blocks out on beds or a flat surface covered with film.
- Moisten them evenly with water to full moisture capacity.
- Apply a starter dose of macro- and micronutrient fertilizers (the main nutrition is supplied fractionally, along with subsequent irrigation).
- Sow the seeds or plant rooted cuttings.
| Nutrition variant | Mineral fertilizer | Application rate for cucumbers, g/m² | Application rate for tomatoes, g/m² |
|---|---|---|---|
| Variant I | Diammonium phosphate | 66 | 72 |
| Magnesium sulfate | 50 | 50 | |
| Potassium nitrate | 65 | 85 | |
| Variant II | Potassium sulfate | 65 | 85 |
| Carbamide (urea) | 52 | 60 | |
| Magnesium sulfate | 50 | 50 | |
| Double superphosphate | 68 | 73 | |
| Variant III | Potassium-magnesia | 100 | 130 |
| Carbamide (urea) | 52 | 60 | |
| Double superphosphate | 68 | 73 |
| Micronutrient fertilizer | Application rate for cucumbers, g/m² | Application rate for tomatoes, g/m² |
|---|---|---|
| Ammonium molybdate | 0.5 | 0.4 |
| Iron sulfate | 1.2 | 1.5 |
| Boric acid | 0.5 | 0.5 |
| Cobalt sulfate | 0.25 | 0.25 |
| Manganese sulfate | 0.75 | 0.70 |
| Copper sulfate | 0.25 | 0.25 |
| Zinc sulfate | 0.10 | 0.25 |
Hollow peat pots are used for growing transplants of vegetable, ornamental, forest, and fruit crops. They are made from a mixture of sphagnum peat (at least 70%) and cardboard or brown wood pulp (no more than 30%) with the addition of chalk, nitrogen, and surfactants. Manufacturers produce them as individual round or square pots, as well as in blocks of 6 and 12 units. To ensure the root system develops without deformation, the pots are filled with light peat substrates.
Dry pressed peat briquettes in the shape of cylinders are also used for plants with an isolated root system. They consist of poorly decomposed sphagnum peat, chalk, and a complex of macro- and microelements. Briquettes are supplied in a biodurable paper shell (type A) or without it (type B).
- Briquette volume when wet — increases by 5–6 times
Workflow for using peat briquettes:
- Place the dry briquettes in a tray or container.
- Gradually pour water into the bottom of the container until the substrate is completely swollen.
- Sow seeds or prick out seedlings into the ready moist substrate.
Soaked briquettes can be used both as individual containers and as a loosening and fertilizing additive for soil mixtures. When growing crops in pure briquettes, monitor their condition regularly and provide timely liquid top dressing.
Production of peat-humic and peat-mineral fertilizers
Physicochemical processing of peat allows it to be converted from an inert raw material into a biologically active fertilizer with a high content of available nutrients.
Peat-ammonia fertilizers (PAF) are produced directly on farms. For this purpose, peat is treated with ammonia water or liquid ammonia. Under the action of the alkaline agent, the excess acidity of the raw material is reduced and its organic matter is activated: the amount of water-soluble humic acids and nitrogen available to plants increases by 10–15 times.
Peat-mineral fertilizers (PMF) are prepared by mixing peat with mineral fertilizers and limestone. For every 1 kg of raw peat (with 55% humidity), the following is added:
- phosphorite flour (1 kg) or simple superphosphate (21 kg);
- potassium chloride (7 kg) or potash salt (11 kg);
- lime flour — 50–45 kg/t (if the pH of the initial peat is 2.5–3.0) or 40–35 kg/t (at pH 3.0–3.5).
| Quality indicator of finished PMF | Standard value |
|---|---|
| Humidity | no more than 65% |
| Ash content | no more than 30% |
| Acidity of salt suspension (pH) | at least 5 |
| Phosphorus content | 0.6% |
| Potassium content | 0.6% |
| Contamination with foreign impurities | no more than 10% |
Peat-mineral-ammonia fertilizers (PMAF) are complex growth stimulants. The ammonia included in their composition converts part of the peat's organic matter into a water-soluble form, while phosphorus and potassium additives provide plants with balanced nutrition. Peat of any type is suitable for the production of PMAF.
Use of peat for the production of PMAF fertilizers
Peat-mineral-ammonia fertilizers (PMAF) are well-suited for gardening and growing vegetable crops. Depending on the volume of added mineral additives, they are divided into four grades: PMAF-1 (low concentration), PMAF-2 (medium), PMAF-4K and PMAF-6K (high). The production of these fertilizers is organized according to two main technological schemes.
The first scheme involves adding all mineral components to the piles of milled peat immediately before stacking. According to the second scheme, fertilizers are prepared using dosing-mixing stations from peat that has already been gathered into stacks. The choice of technology depends on the technical equipment of the farm and the planned volumes of harvesting.
| Quality indicator of peat | Standard for PMAF |
|---|---|
| Ash content | no more than 25% |
| Degree of decomposition | at least 15% |
| Humidity | 50–60% |
| Iron oxide | no more than 5% |
| Calcium oxide | no more than 5% |
| pH | 2.5–6.0 |
Technology for preparing peat composts
Composting is a biothermal process in which organic matter is mineralized and turned into humus under aerobic conditions. During the maturation process, the mixture heats up to 60 °C under the influence of thermophilic microorganisms. Such heating destroys helminth eggs, fly larvae and pupae, weed seeds, as well as pathogenic non-spore-forming microorganisms.
To create an effective compost, two types of components with different resistance to decomposition are combined. The first group consists of manure, slurry, poultry manure, or feces, which are rich in nitrogen and active microflora. The second group includes peat, straw, sawdust, bark, or lignin — water-absorbing materials that decompose poorly without composting. When mixed, the peat retains the released ammonia and liquid, and its own nitrogen converts more quickly into a form available to plants.
Peat is rich in nitrogen, but it exists in an unavailable organic form. Composting with manure solves this problem by converting nitrogen into an assimilable form while simultaneously enriching the mixture with phosphorus and potassium.
Preparing peat for composting requires a complex of land reclamation and field operations. The quality of the raw material directly affects the intensity of microbiological processes in the heaps. Before being added to the compost, finished peat must be checked for compliance with technological standards.
- Draining the peat bog, clearing shrubs and hummocks, and removing the top layer (surface vegetation).
- Ploughing and loosening in several passes with disc and spike harrows.
- Raking the dried peat into windrows 1.5–2 m high.
- Drying the peat in windrows until the humidity is less than 60 %.
| Physicochemical indicator | Requirement for peat used for composting |
|---|---|
| Ash content | no more than 25 % |
| Degree of decomposition | at least 20 % |
| Humidity | no more than 60 % |
| Wood particle content | no more than 10 % |
| Size of peat particles and wood residues | no more than 60 mm |
Finished mixtures are classified by their composition into peat-manure, peat-slurry, peat-poultry manure, and peat-fecal composts. Peat-manure composts remain the most common and effective fertilizer on farms. When preparing them, layer-by-layer, focus, pad, or trench methods are used. Mixing peat with manure helps reduce the acidity of the mixture, activate microflora, and minimize nitrogen losses.
- Optimal ratio of manure to peat — 1:1 or 1:2
- Maximum peat humidity — no more than 60 %
- Height of the finished pile — 2 m
- Width of the finished pile — 3–4 m
The layer-by-layer method of laying compost can be applied at any time of the year, directly in the field or near farms. First, a 50 cm thick layer of peat is laid and leveled with a bulldozer, after which manure is spread over it. The layers are alternated until the required height of the pile is reached, and the heap must be finished with a protective layer of peat.
In winter, the heap must be laid in one or two days; otherwise, the manure will freeze and the process of biothermal decomposition will stop.
Compost laying technologies: focus, pad, and trench methods
The choice of technology for preparing peat composts depends on the season of work, the volumes of preparation, and the equipment available on the farm. Proper laying of heaps and compliance with the temperature regime determine the speed of fertilizer maturation and the preservation of nutrients within it. This allows for obtaining high-quality organic fertilizer with minimal labor costs.
The focus method is optimal for winter preparation at air temperatures down to -20 °C. Peat acts as a thermal insulator, preventing the manure from freezing and stopping fermentation processes. The heap is formed in a specific sequence that ensures uniform maturation of the mass:
- A base layer of peat 30–50 cm thick is laid on the site.
- On top of it, 200–300 kg heaps of manure are distributed every 1–1.5 m.
- The heaps are covered with a second layer of peat 50 cm thick, forming a heap 4–6 m wide at the base and up to 3 m high.
- When a thaw or stable positive temperatures arrive, the mixture is stirred with a bulldozer and laid into piles again to mature for 3–4 months.
The pad method is used during the spring-summer and winter periods. A peat bed 25–30 cm thick is formed on the site, manure is unloaded, and the components are mixed with a heavy disc harrow in 2–3 passes. Then, the mixture is raked into piles 4–6 m wide and 3–4 m high with a bulldozer without compaction. If peat and manure are delivered by organic fertilizer spreaders, leveling with a bulldozer is not required. The maturation time for such composts is from 4 to 6 months, depending on the degree of peat decomposition.
The size of the site for composting using the pad method is calculated by the formula:
Sn = Qt / (h × γ)
where Sn — area of the site (m²), Qt — mass of peat in the compost (t), h — height of the peat layer on the site (m), γ — density of peat (t/m³).
The trench method is suitable for year-round preparation of large volumes of fertilizer. The technology requires a concrete trench and storage areas for raw materials. Manure or poultry manure is unloaded from one side of the trench, and peat is supplied by a bulldozer from the opposite side. Simultaneously, mineral additives are introduced, all components are mixed with a PFP-1.2 mixer or a bulldozer, after which the mixture is laid in piles and covered on top with a layer of peat 0.2–0.3 m thick.
| Composting method | Additive used | Dosage per 1 ton of raw peat | Effect of the additive |
|---|---|---|---|
| Alkaline | Lime | 30–50 kg | Neutralizes the excess acidity of the peat |
| Wood ash (or peat ash) | 50–75 kg (2–2.5 times more for peat ash) | ||
| Acidic | Phosphate rock | 10–20 kg | Peat acids dissolve the powder, converting phosphorus into a form easily assimilated by plants |
Specifics of preparing peat-slurry and peat-fecal mixtures
Composting peat with liquid organic waste (manure slurry and feces) allows for binding nitrogen, preventing its volatilization, and accelerating the decomposition of peat matter. The resulting fertilizers are highly effective and suitable for any crop. To preserve nutrients, it is important to strictly observe the stacking technology and application rate of additives.
All types of peat, except for calcareous ones, are suitable for composting with manure slurry.
Peat-slurry composts are prepared in manure pits (in winter) or in field windrows and on drained peatlands (in summer). With the first method, a windrow is formed 3–4 m wide and 1.5–2 m high, a channel 50–80 cm deep is made on top, and the slurry is poured into it. In the layer-by-layer method, peat is laid in layers of 30–50 cm up to a total windrow height of 1.5–2 m, soaking each layer except the top one. A new layer is added only after the previous one has heated up, which usually happens after 4–5 days.
During prolonged storage of the peat-slurry mixture, nitrification and denitrification processes occur, leading to nitrogen loss. To conserve nitrogen, potassium chloride is added to the mixture, which inhibits the activity of nitrifying bacteria. The finished compost can be applied 1–1.5 months after stacking. If the fertilizer is planned to be used earlier than this, compacting the pile during formation is not required.
- Consumption of manure slurry — 0.5–1 t per 1 t of peat
- Potassium chloride additive — 0.5–1% by weight of the compost
- Phosphate rock additive — 20–30 kg per 1 t of compost
- Application rate before ploughing or cultivation — 15–25 t/ha
- Application rate for top dressing — 5–10 t/ha
Peat-fecal composts are prepared in spring and summer directly in the fields or on drained peatlands in a ratio of feces to peat of 1:1 or 1:2. The peat is laid in two parallel windrows with a depression in the middle, and the thickness of the peat layer at the junction of the windrows should be 40–50 cm. The end walls are formed with a bulldozer, after which feces are poured into the depression. When the peat has completely absorbed the liquid, the entire mass is raked into windrows with a bulldozer without compaction.
Fresh, non-composted mixtures of peat and feces work in the fields as effectively as matured fertilizers. However, using them immediately is dangerous: raw feces carry pathogenic bacteria and helminth eggs. For safe use, the mixture must undergo self-sterilization in loosely laid piles for 1–1.5 months.
Each ton of peat-fecal compost at a peat-to-feces ratio of 2:1 replaces about 1.5 tons of manure in its fertilizing value, exceeding it in its effect on yield.
During the composting process, the temperature inside the pile must rise to 56–60 °C — only under this condition do dangerous disease pathogens die. Due to the risk of infections and infestations, it is strictly not recommended to use such composts for vegetable crops.
If the temperature in the windrow during the holding period is below the required 56–60 °C, using such fertilizer in the fields is permitted only in the second year after stacking. One should not delay the maturation periods too long, as the mixture quickly loses nutrients during prolonged storage. If prolonged storage of feces is inevitable, compost them with a higher proportion of peat (a wider component ratio).
| Crop | Application rate of peat-fecal compost as a primary fertilizer, t/ha |
|---|---|
| Grain crops | 15–20 |
| Potato, silage, and forage crops | 20–25 |
Preparation of peat-plant and peat-manure composts
Peat-plant composts are prepared directly on peatlands by ploughing in legumes grown on them. In terms of efficiency, they are not inferior to semi-rotted manure. Depending on the technology, either the entire green mass is ploughed in (for example, alkaloid lupine to obtain peat-green manure compost) or only the root and stubble residues.
The technology for preparing peat-green manure compost consists of the following stages:
- Rolling the plant mass in the flowering phase.
- Grinding green manure crops and ploughing them into a depth of 12–14 cm.
- Discing the surface of the peatland 15–20 days after ploughing.
- Raking the peat-plant mixture into windrows 1.5–2 m high, followed by holding for 1–2 months.
Peat-manure (poultry) composts are prepared at special sites near poultry farms or directly on farms. The mixture heats up quickly and matures in 1–2 months during the warm season.
The technological process for establishing peat-manure compost consists of the following steps:
- Forming a base layer of peat 20–25 cm thick, onto which 10–20 cm of poultry manure is spread.
- Mixing the layers using heavy disc implements.
- Forming a windrow with a bulldozer (width — at least 3 m, height — 2–2.5 m, length — arbitrary).
The nutritional value of peat-manure compost depends on the humidity of the initial components. Fertilizer prepared from two parts of standard peat and one part of manure with 90% humidity, at a final humidity of 70%, contains essential nutrients in the following concentrations:
- Total nitrogen — at least 0.7%
- Manure nitrogen — 0.2%
- Phosphorus — 0.15%
- Potassium — 0.08%
If standard peat and manure with 80% humidity are used in equal proportions (1:1) for preparation, then at the same final humidity, the concentration of nutrients in the finished fertilizer will increase by 1.5 times.
| Crop group | Application rate of peat-manure compost, t/ha |
|---|---|
| Grain crops | 10–15 |
| Row crops | 20–25 |
| Vegetable crops | 30–40 |
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