Humus accumulation, humification, and humic acid composition in soils of two post-mining chronosequences after coal mining

Abstract

Purpose To assess how the rates of humus formation and humification are affected by land use and age of ecosystems, this study investigated soil development in two post-mining chronosequences (spoil heaps formed from open-cast coal mining near Sokolov, Czech Republic). The following characteristics were measured: content, composition, and properties of humic acids; organic carbon (C) and total nitrogen (N) contents; pH; and amorphous iron content. Materials and methods Two chronosequences were studied. One consisted of unreclaimed spontaneously revegetated spoils (3, 12, 20, and 40 years old). The other consisted of heaps that were reclaimed by planting alder in graded heaps (7, 15, 20, 30, and 40 years old). Humus and iron contents as well as pH were determined, and humic acids were extracted for detailed chemical analyses (C, H, N, 13 C-NMR, and pyrolysis mass-spectrometry).Results and discussion C and N accumulated faster in the reclaimed sites than in the unreclaimed sites; organic matter accumulation results in the decrease of pH in all soils and in spontaneous sites also increase of amorphous iron content. Humic acids (HA) and fulvic acids (FA) increased with the site age in both chronosequences. The CHA/CFA was higher in the reclaimed soils than in the unreclaimed soils, and the CHA/CFA ratio increased with age in the unreclaimed soils.Humic acid aromaticity was higher in the reclaimed site than in the unreclaimed sites but increased with the age of unreclaimed sites. H and O content decreased with age of reclaimed soils. Humification led to an increase in HA caloricity in the reclaimed sites but not in unreclaimed sites because of the influence of residual wax-type substances in the unreclaimed sites. Degree of HA oxidation (ω) for the reclaimed plots was similar to that in typical zonal soils but was highly variable in unreclaimed soils. Conclusions Relative to spontaneous revegetation in the unreclaimed sites, reclamation increased the rates of humus accumulation, humification, and humus acid transformations. The differences between reclaimed and unreclaimed sites, however, decreased with site age and were very small in 40-year-old sites. These differences correspond to the rapid colonization of the reclaimed sites and the slow colonization of the unreclaimed sites by soil biota.

Mobilization of cadmium from festuca ovina roots and its distribution between operational fractions in soil

“…There is a high probability that the Cd accumulated in roots (in the hydroponic cultivation stage) could have accelerated the aging and dying of the root material. Root exudates and dead roots are known to be good sources of carbon and energy for soil microorganisms, and, together with microbial metabolites, are substrates for humification, raising the amounts of soil organic carbon (Abakumov et al 2013). In such cases, during humus accumulation, metal-organic complexes can also be incorporated into soil organic matter (Renella et al 2004, Semenov et al 2013.…”

“…They increase the resistance of the upper soil layer to water and wind erosions (Ernst 2005, Beats et al 2006, and together with rhizospheric microorganisms, act as factors in accelerating the rates of plant residue degradation and in encouraging humus accumulation (Abakumov et al 2013). The water-soluble root exudates and mucilage of fully functional roots, the sloughing of root cells, as well as the accumulation of dead roots are sources of organic carbon and energy for rhizospheric microorganisms (Hütsch et al 2002).…”

“…The water-soluble root exudates and mucilage of fully functional roots, the sloughing of root cells, as well as the accumulation of dead roots are sources of organic carbon and energy for rhizospheric microorganisms (Hütsch et al 2002). Furthermore, the aforementioned act as substrates for humification (Abakumov et al 2013). Humic substances, in addition to the stable products of humification such as humus acids (fulvic and humic acids) and humin, also contain easy degradable proteins, polysaccharides, fatty acids, alcohols, esters and others substances originating from microorganism and plant metabolism (Semenov et al 2013).…”

Relationship between soil humus dissimilation, soil biological and chemical properties, and leaf litter characteristics in pure forests

“…The existing studies have demonstrated that the humus content and componential properties exhibited considerable specificity in different forests (Dong et al, 2015;Li et al, 1992). In addition, the humus properties were also significantly changed during the process of forest development and aging or when the dominant species in forests were changed (Abakumov et al, 2013;Cerli et al, 2008;Descheemaeker et al, 2009;Labaz et al, 2014;Trap et al, 2013). Noticeably, the longterm growth of pure forests sometimes will cause the losses of humus components and alterations of humus structure properties in soil (Liu et al, 2009).…”

IUSS SUITMA 6 International Symposium 2011

“…Eleven peer-reviewed papers are being published in this special issue of the Journal of Soils and Sediments, which focus on the properties, processes, evolution, and management of soils in urban and human-altered environments. Targets of study include soils with technic materials (Abakumov et al 2013;El Khalil et al 2013;Houben et al 2013;Huot et al 2013;Nehls et al 2013;Schonsky et al 2013), those with elevated metal contents (Aboudrar et al 2013;Jean-Soro et al 2013), soils in storm water infiltration basins (Coulon et al 2013;El-Mufleh et al 2013), and soils with landmines (Preetz et al 2013).…”