Soil organic carbon contributes to alkalinity priming induced by added organic substrates
journal contributionposted on 06.01.2021, 00:53 authored by F Rukshana, CR Butterly, JM Xu, JA Baldock, Caixian TangCaixian Tang
Organic substrate input stimulates mineralisation of native soil organic matter, resulting in CO2 priming. Our previous studies showed that such CO2 priming enhanced alkalinity release but the mechanisms behind this are unknown. This study used 14C-labelled compounds to investigate the effect of added organic compounds on decomposition of soil organic matter and how this related to the enhanced release of alkalinity. 14C-labelled glucose and malic acid were added at a rate of 1mg Cg-1 to topsoil and subsoil of the Kandosol (pH 5.4-5.8, C 8.9-12.4mgg-1), the Podosol (pH 4.4-4.5, C 1.5-2.9mgg-1) and the Tenosol (pH 4.7-6.1, C 1.9-10.9mgg-1), and incubated for 15d. 21-27% of the added C was mineralised to CO2 in the Podosol while 56-74% was mineralised in other two soils with malic acid being mineralised more than glucose. The CO2 priming, as a result of added C, was substantial, and ranged 110-325μgg-1 for Podosol and 766-1178μgg-1 for the other two soils with the priming being greater in topsoil than subsoil. The addition of both organic compounds resulted in alkalinity priming in the Kandosol and the Tenosol but not in the Podosol; the alkalinity was greater with malic acid than glucose and greater in topsoil than subsoil. The effect of glucose on alkalinity release occurred mainly via NO3 immobilization while the effect of malic acid via ammonification, NO3 immobilization and decarboxylation/decomposition of native soil organic matter. This study confirmed that alkalinity priming occurred with concurrent CO2 priming as a result of Ccompound addition. This alkalinity priming depended on added C source, initial soil pH and soil organic matter content. © 2013 Elsevier Ltd.
This research was supported under Australian Research Council's Discovery Projects funding scheme (DP0877882 and DP120104100). JMX was also supported by the National Basic Research Program of China (2011CB100502).
JournalSoil Biology and Biochemistry
PublisherPERGAMON-ELSEVIER SCIENCE LTD
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Science & TechnologyLife Sciences & BiomedicineSoil ScienceAgricultureAlkalinity primingCarbon cycleCO2 primingDecompositionIndigenous soil organic matterInitial soil pHNitrogen cycleC-14-glucoseC-14-malic acidMICROBIAL BIOMASS-CEXTRACTION METHODCOMPOUNDS DIFFERINITIAL PHMATTERRESIDUESNITRATEMECHANISMSPLANTACIDAgronomy & Agriculture