Fig. 1. Time-series of the CO₂ efflux from soil microcosms.

A Total CO₂ efflux following 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 (N, P, K, S). Each point reflects the average rate of CO₂ efflux at the mid-point of the sampling interval. B Percent of total CO₂ derived from the added glucose. Error bars show standard deviation (n = 4 independent soil microcosms).