Effects of Turning Frequency and Pile Size on the Composting of Dairy Manure

Two variables that directly affect on-farm composting costs are windrow size and windrow turning frequency. However the size of a windrow is limited by the depth of penetration of oxygen and high temperatures and occasional turning is necessary to mix the compost to assure even decomposition and pathogen destruction. In this study, one set of windrows (A) were turned using a self-propelled and tractor drawn windrow turner every three days for a total of 30 turns during 16 weeks. A second set (B) were turned once every 10 days. A third set (C) consisted of much larger piles turned every 10 days. Windrows were divided into three replicates with an approximate dimension of 25ft length, 3-4ft height and 10ft width, and an estimated surface area of 23ft2 . Oxygen and temperature profiles were measured before turning at three depths as well as every 30 minutes thereafter to determine the duration of the effect of turning and to estimate oxygen demand as a function of compost age. Results will be useful in establishing more guidelines for efficient dairy manure compost production.