Liming effects on microbial carbon use efficiency and its potential consequences for soil organic carbon stocks

Summary

This multi-site field study examined whether liming—a potential climate-smart agriculture practice—could increase soil organic carbon stocks by enhancing microbial carbon use efficiency. The researchers found a non-linear (U-shaped) relationship between soil pH and CUE, with CUE lowest at pH 6.4, and demonstrated that long-term liming effects on CUE contributed to overall changes in SOC stocks, though the relationship remained complex and difficult to predict with certainty.

UK applicability

UK agricultural soils frequently require liming to raise pH in acidic conditions; these findings suggest that the SOC impact of liming depends critically on the soil's starting pH, and that pH adjustment to around 6.4 may not optimise microbial carbon retention. UK farmers and advisers should consider site-specific pH responses when using liming as a carbon sequestration strategy.

Key measures

Soil pH (pHH2O), carbon use efficiency (CUE), microbial biomass carbon, abundance of microbial domains, soil organic carbon (SOC) stocks, organic carbon inputs

Outcomes reported

The study measured the effects of long-term liming on soil microbial carbon use efficiency (CUE), microbial biomass carbon, microbial domain abundance, soil organic carbon stocks, and organic carbon inputs across three European long-term field experiments, with laboratory assessments of immediate CUE responses to pH manipulation.

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