Liming is a common agricultural practice for improving acidic soils, but the addition of liming materials may also promote soil carbon dioxide (CO2) emissions, with adverse effects for climate regulation. In grasslands, current understanding of liming impacts on greenhouse gas emissions is limited by a lack of field data on liming and soil respiration. Here we used a two-year field trial and in situ chamber measurements to evaluate the effects of repeated, low-level liming on soil CO2 emissions from an acidic managed grassland with high soil organic matter content. Soil pH, temperature and moisture were measured during the experiment, as well as microbial and plant biomass, in order to assess possible liming-induced changes to drivers of grassland carbon cycling. Soil CO2 emissions showed significant variation during the two-year study, driven primarily by fluctuations in soil temperature. Soil respiration rates were unaffected by liming treatment, despite significant lime-induced increases in soil pH. Liming was associated with a decrease in biomass produced per gram nitrogen, as well as a decrease in forage C:N in the second year and transient decreases in microbial C:N, but neither plant nor microbial biomass showed significant responses to liming addition. Collectively, our results suggest that positive effects of low-level liming on plants and soil are not offset by increases in soil CO2 emissions in situ, highlighting the potential for sustainable liming practices in fertilized grasslands.
Keywords: Acid soils; CO(2) emissions; Ca-amendment; Plant biomass; Soil microbial biomass; Soil pH.
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