Glucose-induced priming effects in soils across Europe

The objectives of this study were (i) to quantify and compare the priming effect (PE) in 126 soils from cropland and seminatural (i.e., forests and grasslands) ecosystems, as well as in cropland soils cultivated with three important crop types in Europe: cereals, industrial crops and fruit and vineyard orchards; and (ii) model the main factors controlling the PE under contrasting land uses. PEs were measured after soil 13C-glucose addition and incubation at 20 °C for 35 days. These microcosms were also used to assess basal respiration for the same period. Soil and climate data were obtained from the same LUCAS 2018 survey and online databases. Data on microbial biomass C and enzyme activities were obtained from previous published studies. Bacterial and fungal biomass was quantified through fatty acid methyl esters (FAME) analysis. Random Forest analysis and structural equation modeling (SEM) were used to explore the main drivers of the PE.