Nitrogen adsorption study of the surface properties of the secondary transformed peat-moorsh soils
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Instytut Agrofizyki im. Bohdana Dobrzańskiego, Polska Akademia Nauk, ul. Doświadczalna 4, 20-290 Lublin 27, Poland
Publication date: 2020-05-16
Acta Agroph. 2000, (26), 65–73
The influence of moorshing processes of peat soils on nitrogen adsorption and on specific surface area was investigated. Soil samples for study were taken from differently moorshified peat-moorsh soils, characterizing by W1 index ranged from 0.44 to 0.82. The samples represented two kinds of moorsh fonnations, i.e., peaty moorsh (Z1) and propert moorsh (Z3). Nitrogen adsorption measurements at 77 K were used for determining the surface area and pore volume. The Brunauer-Emmett-Teller (BET) method was used as the standard procedure for determination of the surface area. The adsorption and desorption isotherms of N2 on peat-muck soils at 77 K exhibited similar shape and all belonged to the type II, according to BET classification. The adsorption increased in the series of the soil samples Nos 11<1<13<12 and 10<5<6<8 for the peaty moorsh (Z1) and for the proper moorsh (Z3), respectively. The above series agreed with the changes of the index of the secondary transformation, W1, except for the samples Nos 12 and 5. The nitrogen-BET specific surface area of soil samples ranged from 2.45 to 4.90 m2 g–1, and no direct relation between the surface area and the index of the secondary transformation, W1, was found. When soil samples are first grouped into the classes Z1 and Z3, and then, for each group, arranged according to the value of the index W1, the relationship between W1 and the specific surface area became more visible. Generally, for the proper moorsh (Z3), an increase of the nitrogen-BET surface area and a decrease of the pore volume were correlated with the increase of the W1 index (except for the samples Nos 8 and 5). In the case of the peaty moorsh (Z1) a decrease of the nitrogen-BET surface area and an increase of the pore volume were connected with the increase of the W1 index, (except for the samples Nos 12 and 13).