Biodrying Manure on a Dairy Farm

Dairy farms are coming under increasing pressure to control the odors and contaminants from their operations. Often nutrient management plans designed to protect water quality prescribe manure storage. Liquid storage and handling has been the method most farms have used. Studies have shown that spreading liquid manure when soils are near saturation or when they are likely to become saturated before crop uptake can occur can result in significant nutrient and bacterial discharges to the water through tile lines and runoff. Stored manure can produce significant objectionable odors both during storage and when spread. Catastrophic failure of liquid systems is a risk that many farms want to avoid.Biodrying as described in this paper is a system that has the potential to meet the environmental concerns. It can meet the need for water quality protection by increasing the likelihood of export. It can provide a stabilized solid for spreading on hay ground during the growing season. Biodrying will meet the farm's need for odor control. Smaller farms need of a solid based treatment system would be addresses as well.The design of a Biodrying process on an 85 cow dairy farm in the NYC Watershed will be described. This work has been funded by a grant from NYSERDA and is being constructed in the winter of 2000–2001. This will include designing and building a composting shed, installing and monitoring the forced air system, and establishing a procedure for processing the manure. If managed carefully, the heat generated by aerobic composting can provide the energy to reduce 12% DM manure to a 60% DM residual. The compost would be reduced one half in volume and to one fifth the weight of the original manure due to water loss and solid conversion to gasses.Preliminary analysis shows that the cost of operating the system minus the cost of additional benefits including off site sales is less than the cost of conventional liquid storage and land spreading that would meet the environmental regulations for the farm. If successful, this system would have application on many dairy farms.