Static respiration indices to investigate compost stability: Effect of sample weight and temperature and comparison with dynamic respiration indices

► We measured static respiration indices using five sample sizes at two temperatures. ► At 35°C, as sample size increased, respiration indices decreased. ► Respiration activity at 35°C was greater than that at 20°C for some sample sizes. ► Static respiratory quotients were constantly between 0.8 to 1.2 after 7days. ► Static indices were 2–2.5 lower than dynamic respiration indices at 35°C. Goal of this work was to study the effect of sample weight and temperature on the microbial respiration indices of a static microbial respiration test used to quantify compost stability. The static respiration tests (SRT) were performed at two different temperatures (20°C and 35°C) using five different sample weights (19, 38, 56, 75 and 94dry g). Results showed that at 35°C, as sample weight increased, the magnitude of the respiration indices reduced. In addition, the 35°C temperature resulted in higher static respiration activity indices compared to that at the 20°C for two sample weights. The static respiration tests led to 2–2.5 times lower oxygen-related indices compared to those calculated in dynamic respiration tests (DRT); the 7-day CO2 cumulative generations were, however, almost similar for both types of tests. Respiratory quotients (RQs) were constantly between 0.8 to 1.2 during the SRT.