Long-term liming mitigates the positive responses of soil carbon mineralization to warming and labile carbon input

Abstract

Liming, as a common amelioration practice worldwide, has the potential to alleviate soil acidification and ensure crop production. However, the impacts of long-term liming on the temperature sensitivity (Q₁₀) of soil organic carbon (SOC) mineralization and its response to labile C input remain unclear. To fill the knowledge gap, soil samples were collected from a long-term (∼10 years) field trial with unlimed and limed (CaO) plots. These soil samples were incubated at 15 °C and 25 °C for 42 days, amended without and with ¹³C-labeled glucose. Results showed that compared to the unlimed soil (3.6-8.6 mg C g^-1 SOC), liming increased SOC mineralization (6.1-11.2 mg C g^-1 SOC). However, liming significantly mitigated the positive response of SOC mineralization to warming, resulting in a lower Q₁₀. Long-term liming increased bacterial richness and Shannon diversity as well as their response to warming which were associated with the decreased Q₁₀. Furthermore, the decreased Q₁₀ due to liming was attributed to the decreased response of bacterial oligotrophs/copiotrophs ratio, β-glucosidase and xylosidase activities to warming. Labile C addition had a strong impact on Q₁₀ in the unlimed soil, but only a marginal influence in the limed soil. Overall, our research highlights that acidification amelioration by long-term liming has the potential to alleviate the positive response of SOC mineralization to warming and labile C input, thereby facilitating SOC stability in agroecosystems, especially for acidic soils in subtropical regions.

Keywords: Acidification amelioration; Enzyme activity; Microbial diversity; Oligotrophs/copiotrophs; Temperature sensitivity.