1. What is peat?
Peat is an organic fossil formed as a result of the death and incomplete decay of marsh plants under conditions of increased moisture and lack of oxygen, representing the first stage of the transformation of plant material along the path of its formation into coal.
2. The botanical composition of peatis the amount of remains of peat-forming plants that make up the plant fiber of peat, denoted by the letter R and expressed in %. Each type of peat is characterized by a certain type of vegetation. Using a microscope, all plant residues that form a particular peat are determined. Then the name is given, for example, sedge lowland, sedge-sphagnum, high sphagnum, etc.
3. Humidityis the amount of water expressed as a percentage of the total mass. It is denoted by W and expressed in %. In natural occurrence, humidity can reach up to 95%. With various methods of peat harvesting (mechanical or vacuum cleaning), peat moisture content ranges from 45 to 65%.
The most acceptable humidity for preparing substrates is 50…60%. Such peat will absorb water well and will retain it for a certain time. If the humidity is below 45%, then it takes a certain time for the peat to soak.
4. Acidityis the ability of peat to exhibit the properties of acids and alkalis when interacting with water or salt solutions. Determined by the degree of concentration of hydrogen ions (pH units).
Depending on the state in which H+-ions are in peat, active and exchangeable acidity are distinguished.
Active acidity is associated with the presence of hydrogen ions in the soil solution. It is due to the presence in it mainly of carbon dioxide, acidic and salts, as well as organic acids formed during the decomposition of organic matter. Active is determined by the pH value in the aqueous extract.
Exchangeable acidity is determined by the presence of exchangeable hydrogen and aluminum ions in the absorbing complex. Exchangeable acidity is the more mobile part of hydrogen ions, which can be transferred into solution when peat is treated with a solution of neutral potassium chloride salt.
Acidity is:
When pH = 5.5…6.5 is written, it means that exchangeable acidity (pHKCl) should not be lower than 5.5 pH units, and active acidity (pH2O) should not be more than 6.5 pH units.
To bring acidity to the required values, lime materials are used – slaked limestone (dolomite) flour, chalk.
The neutralization period occurs in the first minutes of mixing and over time, depending on the temperature, can last 5-10 days.
5. Electrical conductivity (EC)is the ability of a material to pass electric current through itself. Conductivity is the reciprocal of resistance. Expressed in mS/cm. Based on the electrical conductivity of the extract, one can judge the concentration of dissolved salts in the solution. Moreover, all salts in the solution are measured, and not just fertilizer salts.
For each plant there is an optimal electrical conductivity value. The optimal electrical conductivity of the substrate ranges from 0.8…1.5 mS/cm.
The electrical conductivity of the substrate affects the ability of nutrients to be absorbed by plants. High EC levels are associated with poor shoot and root growth and the occurrence of root rot. Low EC levels cause plant growth to slow down and leaves begin to turn yellow.
6. Bulk densityis the ratio of the mass of a substance to the occupied volume, denoted by ρ, kg/m3. The bulk density can be at actual moisture content or at conditional moisture content. The conditional humidity is considered to be 40%.
The bulk density of transitional peat is small, 150-200 kg/m3. This feature of peat makes it easier to work with in greenhouses.
7. Ash contentis the ratio of the mass of the mineral part of peat remaining after calcination to the mass of dry peat. It is usually expressed as a percentage of the mass of the analyzed sample and is designated by the letter A.
The ash content depends on the botanical composition. Low-ash sphagnum mosses (high peat) have an ash content of 2.0…4.0%, and wood residues and sedge (transitional, lowland peat) – from 4.5 to 20%. Ash content increases with increasing degree of decomposition.
To produce TPS, peat with an ash content of no more than 15% is used.
8. Fractional compositionis the quantitative distribution of particles in a sample depending on their size, expressed as a percentage by weight of the product that passed through a sieve (set of sieves) or remained on each sieve (set of sieves).
9. Peat contaminationis the mass fraction of foreign impurities in peat. Foreign impurities include: wood chips, pieces of rhizomes, pieces of peat with a low degree of decomposition, peat moss, etc.
