Influence of ameliorating soil acidity with dolomite on the priming of soil C content and CO 2 emission

Abstract

Lime or dolomite is commonly implemented to ameliorate soil acidity. However, the impact of dolomite on CO₂ emissions from acidic soils is largely unknown. A 53-day laboratory study was carried out to investigate CO₂ emissions by applying dolomite to an acidic Acrisol (rice-rapeseed rotation [RR soil]) and a Ferralsol (rice-fallow/flooded rotation [RF soil]). Dolomite was dosed at 0, 0.5, and 1.5 g 100 g⁻¹ soil, herein referred to as CK, L, and H, respectively. The soil pH_(H2O) increased from 5.25 to 7.03 and 7.62 in L and H treatments of the RR soil and from 5.52 to 7.27 and 7.77 in L and H treatments of the RF soil, respectively. Dolomite application significantly (p ≤ 0.001) increased CO₂ emissions in both RR and RF soils, with higher emissions in H as compared to L dose of dolomite. The cumulative CO₂ emissions with H dose of dolomite were greater 136% in the RR soil and 149% in the RF soil as compared to CK, respectively. Dissolved organic carbon (DOC) and microbial biomass carbon (MBC) increased and reached at 193 and 431 mg kg⁻¹ in the RR soil and 244 and 481 mg kg⁻¹ in the RF soil by H treatments. The NH₄⁻-N and NO₃⁻-N were also increased by dolomite application. The increase in C and N contents stimulated microbial activities and therefore higher respiration in dolomite-treated soil as compared to untreated. The results suggest that CO₂ release in dolomite-treated soils was due to the priming of soil C content rather than chemical reactions.

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