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Decomposition of soil organic matter as affected by clay types, pedogenic oxides and plant residue addition rates

Research output: Contribution to journalJournal article

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  • Mandeep Singh
  • Binoy Sarkar
  • Nanthi S. Bolan
  • Yong Sik Ok
  • Gordon Jock Churchman
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<mark>Journal publication date</mark>15/07/2019
<mark>Journal</mark>Journal of Hazardous Materials
Volume374
Number of pages9
Pages (from-to)11-19
Publication StatusPublished
<mark>Original language</mark>English

Abstract

The interactive effects of the types and contents of soil clay fractions (SCFs) and plant-residue addition rates on soil organic carbon (SOC) stabilisation are largely unknown. We conducted incubation experiments by amending a sandy soil sample with kaolinitic-illitic, smectitic and allophanic SCFs and adding wheat residues to the mineral mixtures to compare their C stabilisation capacity. The rate of carbon (C) decomposition was higher in the kaolinitic-illitic SCF followed by smectitic and allophanic clay minerals. The supply of easily degradable C substrate from decomposing residues markedly influenced the SCFs’ abilities to stabilise SOC. The removal of sesquioxides from the SCFs significantly decreased their C stabilisation capacity, which coincided with a decrease in the dehydrogenase activity of the mineral-residue mixture. The allophanic SCF showed the least microbial activity and the greatest C stabilisation due to having a higher proportion of micropores (75%). The high C stabilisation capacity of allophanic SCF could also be explained by its high specific surface area (119 m2 g−1). The results of this study are helpful to understand the role of various SCFs in stabilising added C originating from external wheat residue addition but warrant further validation under field conditions.