Fig. 1: Interactions between litter quality and soil mineralogy determine the amount of carbon (C) respired from added litter and primed from pre-existing soil organic matter (SOM).

Cumulative sum of litter-C respired (a) and total SOM derived (primed) C (b) over the course of the 126-day incubation. CO₂ sampling was conducted daily from days 0-10 and then on days 13, 15, 17, 20, 24, 28, 31, 34, 38, 41, 45, 49, 56, 63, 70, 77, 84, 91, 98, 105, 112, 119 and 126. The cumulative sum of litter-C respired is presented as a percentage of the C added as litter whilst primed C represents pre-existing C respired from litter addition treatments in excess of C respired from no litter control microcosms. Cumulative litter-C respired data are presented as mean values (n = 5) ± 1 standard deviation (displayed as error bars). Boxplot centre lines represent the median, box limits indicate the first and third quartiles, whiskers extend to the minimum and maximum values within 1.5x of the interquartile range and circles represent outliers (defined as points >1.5 times the interquartile range). All statistics were derived from n = 5 independent samples. Between group differences in primed C were compared using estimated marginal means (emmeans) to determine the effect of litter quality by mineral treatment. The two-sided p-values from emmeans tests are adjusted for multiple comparisons using the Benjamini–Hochberg (BH) procedure (displayed within the plots). The sample size ‘n’ represents samples taken from independent experimental units (soil incubations). Source data are provided as a Source Data file. Exact P-values are available in the corresponding Source Data file.