Reduction of moss peat acidity
The amount of liming material required depends on the pH of the peat, the degree of decomposition, the particle size of the liming material, its chemical and physical properties. However, liming material and peat volume in kg / m3 have the greatest impact. Bulk volume of low-density peat is 150–200 kg /m3, but high-volume peat – 300–400 kg/m3. The moisture of the peat when surface milling is also important. The hotter the weather and the drier the peat, the more it is dusted. Therefore, more liming material is needed for peat extracted from deeper bog layers during dry and hot weather and separated through a fine sieve. Such peat will have the bigger volume weight.
The water solubility of limestone has a very important influence on the consumption of liming material to neutralize the acidity of peat. The solubility of liming material, in turn, depends on the fineness of grinding and its chemical properties. Limestone flour with a particle size of less than 0.1 mm, when mixed with peat, significantly raises its pH within the first two days even with peat moisture of only 45%. By increasing the moisture content of peat from 45% to 75%, the effect of liming material increases very rapidly. For faster and more complete neutralization, drier peat must be well wetted immediately after liming. To neutralize its acidity, peat with a relative humidity of 60% at + 18C needs at least 24 hours. However, within a week of descaling, the pH increases by about another 0.5-0.6 units, in some cases up to 1.0 unit. The even mixing of peat with liming material is very important, because calcium carbonate, due to its low solubility, remains sedentary in both vertical and horizontal directions.
Peat acidity should be reduced by simultaneous use of two liming materials: limestone flour and dolomite flour. Dolomite flour should not only be used to provide plants with magnesium. They also have another important role to play. Magnesium carbonate is more soluble and faster in water than calcium carbonate. Therefore, the acidity of peat is first reduced by the magnesium carbonate contained in dolomite flour. It has a solubility of more than 100 times the initial dissolution of calcium carbonate in water at 1.52 and 0.014 g / l, respectively, at a temperature of + 20 ° C. Calcium carbonate dissolves slowly and gradually and only after some time begins to significantly reduce the acidity of the peat. This occurs after dissolution of carbon dioxide in water and formation of bicarbonate ions (HCO3-). Calcium bicarbonate Ca (HCO3) 2 is 11,000 times more water soluble than CaCO3.
Decreased peat acidity should be based on an optimum calcium: magnesium ratio of Ca: Mg = 6.5: 1.0 or, more generally, 5-8: 1. This can be achieved by using a combination of limestone and dolomite flour in an average weight ratio of 2: 1.
Dolomite flour contains 28% (27-29%) CaO or 20% Ca and 19% (18-20%) MgO or 11.4% Mg. The average basicity is 97%. Mostly it has fine fractions. The average particle content below 0.25 mm is 87.4%, while coarse particles above 0.5 mm only 2.2%. In addition, 10.4% of the particles in the batch were 0.25 to 0.50 mm. So, after the degree of grinding, dolomite flour is suitable for neutralizing peat acidity.
Also limestone flour we found mostly small particles. In the batch analyzed, the fine particle content (<0.25 mm) was 90.7% on average, incl. the smallest particles (<0.1 mm) were 72.3%. After the degree of crushing, the limestone flour also meets the all requirements. It has an average calcium (Ca) content of 34.5% and magnesium (Mg) content of only 1.1%.
Attention should also be paid to the content of trace elements in liming materials. For example, dolomite flour contains on average: Fe – 0.3%; Mn 0.027%; Zn – 0.0011% and Cu – 0.0005%, but limestone flour respectively: Fe – 0.4%; Mn 0.016%; Zn 0.006% and Cu 0.001%. Both liming materials are virtually free of boron and molybdenum. In trace materials these trace elements are less soluble and can be used more slowly in carbonate compounds.
Liming peat can also be carried out on the farm, but without proper equipment it is difficult to do it qualitatively. In a simple way, peat can be evenly dispersed in the field, then mixed with the required amount of liming material and incorporated into the soil by cultivation.
P.S. Original dolomite flour and limestone flour from Latvian manufacturers were used in the research. These manufacturers supply raw materials to Areapeat propagation , potting and tree nursery peat substrates.
Reduction of moss peat acidity
The amount of liming material required depends on the pH of the peat, the degree of decomposition, the particle size of the liming material, its chemical and physical properties. However, liming material and peat volume in kg / m3 have the greatest impact. Bulk volume of low-density peat is 150–200 kg /m3, but high-volume peat – 300–400 kg/m3. The moisture of the peat when surface milling is also important. The hotter the weather and the drier the peat, the more it is dusted. Therefore, more liming material is needed for peat extracted from deeper bog layers during dry and hot weather and separated through a fine sieve. Such peat will have the bigger volume weight.
The water solubility of limestone has a very important influence on the consumption of liming material to neutralize the acidity of peat. The solubility of liming material, in turn, depends on the fineness of grinding and its chemical properties. Limestone flour with a particle size of less than 0.1 mm, when mixed with peat, significantly raises its pH within the first two days even with peat moisture of only 45%. By increasing the moisture content of peat from 45% to 75%, the effect of liming material increases very rapidly. For faster and more complete neutralization, drier peat must be well wetted immediately after liming. To neutralize its acidity, peat with a relative humidity of 60% at + 18C needs at least 24 hours. However, within a week of descaling, the pH increases by about another 0.5-0.6 units, in some cases up to 1.0 unit. The even mixing of peat with liming material is very important, because calcium carbonate, due to its low solubility, remains sedentary in both vertical and horizontal directions.
Peat acidity should be reduced by simultaneous use of two liming materials: limestone flour and dolomite flour. Dolomite flour should not only be used to provide plants with magnesium. They also have another important role to play. Magnesium carbonate is more soluble and faster in water than calcium carbonate. Therefore, the acidity of peat is first reduced by the magnesium carbonate contained in dolomite flour. It has a solubility of more than 100 times the initial dissolution of calcium carbonate in water at 1.52 and 0.014 g / l, respectively, at a temperature of + 20 ° C. Calcium carbonate dissolves slowly and gradually and only after some time begins to significantly reduce the acidity of the peat. This occurs after dissolution of carbon dioxide in water and formation of bicarbonate ions (HCO3-). Calcium bicarbonate Ca (HCO3) 2 is 11,000 times more water soluble than CaCO3.
Decreased peat acidity should be based on an optimum calcium: magnesium ratio of Ca: Mg = 6.5: 1.0 or, more generally, 5-8: 1. This can be achieved by using a combination of limestone and dolomite flour in an average weight ratio of 2: 1.
Dolomite flour contains 28% (27-29%) CaO or 20% Ca and 19% (18-20%) MgO or 11.4% Mg. The average basicity is 97%. Mostly it has fine fractions. The average particle content below 0.25 mm is 87.4%, while coarse particles above 0.5 mm only 2.2%. In addition, 10.4% of the particles in the batch were 0.25 to 0.50 mm. So, after the degree of grinding, dolomite flour is suitable for neutralizing peat acidity.
Also limestone flour we found mostly small particles. In the batch analyzed, the fine particle content (<0.25 mm) was 90.7% on average, incl. the smallest particles (<0.1 mm) were 72.3%. After the degree of crushing, the limestone flour also meets the all requirements. It has an average calcium (Ca) content of 34.5% and magnesium (Mg) content of only 1.1%.
Attention should also be paid to the content of trace elements in liming materials. For example, dolomite flour contains on average: Fe – 0.3%; Mn 0.027%; Zn – 0.0011% and Cu – 0.0005%, but limestone flour respectively: Fe – 0.4%; Mn 0.016%; Zn 0.006% and Cu 0.001%. Both liming materials are virtually free of boron and molybdenum. In trace materials these trace elements are less soluble and can be used more slowly in carbonate compounds.
Liming peat can also be carried out on the farm, but without proper equipment it is difficult to do it qualitatively. In a simple way, peat can be evenly dispersed in the field, then mixed with the required amount of liming material and incorporated into the soil by cultivation.
P.S. Original dolomite flour and limestone flour from Latvian manufacturers were used in the research. These manufacturers supply raw materials to Areapeat propagation , potting and tree nursery peat substrates.