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

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 94 dry 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.