Fig. 2. Response of soil microbial storage to organic carbon and nutrient supply.

Storage compounds PHB A, B and TAGs C, D in soil 24 h A, C, and 96 h B, D after addition of a readily degradable, ¹³C-labelled carbon source (glucose at 0, 90 and 400 µg C g⁻¹ soil) with or without mineral nutrient supply (ntr.; N, P, K, S). The source of the stored C is shown in contrasting colours as determined by isotopic composition, with light grey error bars reflecting mean±standard deviation of the relative composition. Black error bars show mean ± standard deviation of the total storage compound pools, while colour bar heights show medians, as used in the robust analysis of medians (n = 4 independent soil microcosms, except for 1 treatment in each of TAGs and PHB where n = 3). Lowercase letters above the plots show post-hoc differences in total storage with p < 0.05 (2-sided pairwise comparison of medians with Benjamini-Hochberg adjustment for multiple comparisons).