Changes in Soil Humin Macromolecular Structure Resulting from Long-Term Catch Cropping
Jerzy Weber,
Elżbieta Jamroz,
Lilla Mielnik,
Riccardo Spaccini,
Andrzej Kocowicz,
Irmina Ćwieląg-Piasecka,
Maria Jerzykiewicz,
Danuta Parylak,
Magdalena Dębicka
Affiliations
Jerzy Weber
Institute of Soil Science, Plant Nutrition and Environmental Protection, Wroclaw University of Environmental and Life Sciences, Grunwaldzka 53, 50-375 Wrocław, Poland
Elżbieta Jamroz
Institute of Soil Science, Plant Nutrition and Environmental Protection, Wroclaw University of Environmental and Life Sciences, Grunwaldzka 53, 50-375 Wrocław, Poland
Lilla Mielnik
Department of Bioengineering, West Pomeranian University of Technology in Szczecin, Papieża Pawła VI 3, 71-459 Szczecin, Poland
Riccardo Spaccini
Research Center CERMANU, University of Naples, Piazza Carlo di Borbone, 80055 Portici, Italy
Andrzej Kocowicz
Institute of Soil Science, Plant Nutrition and Environmental Protection, Wroclaw University of Environmental and Life Sciences, Grunwaldzka 53, 50-375 Wrocław, Poland
Irmina Ćwieląg-Piasecka
Institute of Soil Science, Plant Nutrition and Environmental Protection, Wroclaw University of Environmental and Life Sciences, Grunwaldzka 53, 50-375 Wrocław, Poland
Maria Jerzykiewicz
Faculty of Chemistry, University of Wroclaw, 50-137 Wrocław, Poland
Danuta Parylak
Institute of Agroecology and Plant Production, Wroclaw University of Environmental and Life Sciences, Grunwaldzki Sq. 24A, 50-363 Wrocław, Poland
Magdalena Dębicka
Institute of Soil Science, Plant Nutrition and Environmental Protection, Wroclaw University of Environmental and Life Sciences, Grunwaldzka 53, 50-375 Wrocław, Poland
The aim of this study was to assess the effect of long-term catch crop application on the structural properties of humin, which is considered the most recalcitrant fraction of soil organic matter. Soil samples from a 30-year field experiment on triticale cultivated with and without catch crops were analysed to determine the total organic carbon content and fractional composition of humic substances. Meanwhile, humin isolated from bulk soil was analysed to determine its elemental composition and spectroscopic properties measured with UV-Vis, fluorescence, and 13C-CPMAS-NMR. It was found that catch crop farming enhanced the formation of highly reactive humus substances, like low-molecular-weight fractions and humic acids, while decreasing the humin fraction. The higher H/C and O/C atomic ratios of humin and the UV-Vis, fluorescence, and 13C-CPMAS-NMR results confirmed a higher share of oxygen-containing functional groups in humin isolated from the soil with catch crop rotation, also corroborating its greater aliphatic nature. Under the conditions of our field experiment, the results indicated that organic residues from catch crops quickly undergo the decay process and are transformed mainly into highly reactive humus substances, which can potentially improve soil health, while mineral fertilisation alone without catch crops favours the stabilisation and sequestration of carbon.
