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

Lime or dolomite is commonly implemented to ameliorate soil acidity. However, the impact of dolomite on CO emissions from acidic soils is largely unknown. A 53-day laboratory study was carried out to investigate CO 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 soil, herein referred to as CK, L, and H, respectively. The soil pH 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 CO emissions in both RR and RF soils, with higher emissions in H as compared to L dose of dolomite. The cumulative CO 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 in the RR soil and 244 and 481 mg kg in the RF soil by H treatments. The NH-N and NO-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 CO release in dolomite-treated soils was due to the priming of soil C content rather than chemical reactions.