The seasonal effects of manure management and feeding strategies on hydrogen sulphide emissions from stored dairy manure

The influence of temperature and storage time on hydrogen sulphide (H₂S) emissions from two different dairy manures was investigated over four seasons in 2012. Two separate experiments were conducted using dairy manure; (1) water baths at 0, 5, 10, 15, 20, 25 and 30 °C that were incubated for 15 h, and (2) 28-day batch experiment under room temperature. The headspace H₂S concentration increased exponentially after 15 °C and reached a maximum of 3.1 mg/L at 30 °C. After the 4th day of storage, dairy manure emitted an average of 3.6 mg/L of H₂S. However, a small decrease was observed on the 28th day, with a concentration of 2.8 mg/L. Under natural conditions, dairy manure emitted significantly lower H₂S values during winter than during spring, summer and autumn when manure is widely used as fertiliser. Furthermore, regardless of the incubation temperature and storage time, manure from cows fed with concentrate-based feed emitted much higher H₂S (6.5 times) than from cows fed with forage-based feed. These results indicated that the emissions of H₂S from dairy manure could be managed by feeding cows minimal concentrate feed and by handling manure at cooler temperatures or lengthening the retention time.