Finding ways to effectively use the manure on dairy farms is a problem for farmers. And to stay competitive, dairies are now raising more cattle on less land. It's becoming critical to find ways to handle all that waste.
Larry Newton, an animal and dairy scientist with the UGA College of Agricultural and Environmental Sciences, says the manure doesn't have to be a problem anymore. In fact, it can be a valuable resource.
Newton and a team of UGA engineers, scientists and economists have created a manure management system that can take recycling to the limit. It can clean up the environment, maintain a healthy water supply and even help cows give more and better milk.
Working out a system
Newton's system combines parts of other systems, such as
fermentation and hydroponics, that effectively dispose of human
and some industrial wastes in cities.
"We just have to find the right management that works for cattle
and then work out the economics to see if it's worth the producer
using the system," Newton said.
The process
To start the process, the manure is flushed from the dairy barns
where cows are kept and milked. It's then placed in a settling
basin. The solid waste settles to the bottom. The liquid waste is
then siphoned from the top and sent to a machine called an
anaerobic digester.
The remaining solid waste in the basin can be composted or
treated to produce a product more easily transported away from
the dairy and applied as fertilizer.
The digester uses a fermentation process without oxygen to
produce methane gas, which reduces the odor.
"The main purpose of the digester is to convert the plant
nutrients in the liquid waste into more digestible forms for
plant roots to absorb," Newton said.
The nutrient-rich wastewater is then sent through greenhouses,
where forage plants are grown in trays using the wastewater
without soil. This is called hydroponic production.
Self-sustaining
The methane gas from the digester can power water heaters or heat
the greenhouses where the digester liquid is used to
hydroponically grow the forage plants cattle can feed on.
After the plants filter and absorb the nutrients from the
digester liquid, it could potentially be used for the cattle's
drinking water. This would reduce the use of water pumped from
the groundwater supply.
Newton is confident the system will work. But it may not be for
everybody.
"It will be there as an option for some producers, especially
those with a limited land base for dairy," he said.
Newton will test his system at the Coastal Plains Experiment
Station dairy facility in Tifton, Ga.
"That's what we (farm scientists) are here for," he said. "We can
test to see if things like this work and where they might fit
into a farmer's operation."
Extra benefits
Because of the change in seasons and feeding practices on most
dairies, fresh forage is not always available to cattle. But
cattle that feed on fresh forage could produce more milk, Newton
said. This could help farmers and shoppers. Newton's system could
provide year-round forage.
A bonus is that conjugated linoleic acid is found in highest
concentrations in the meat and milk of animals that eat fresh
forage. Conjugated linoleic acid has been found to reduce bad
cholesterol and the growth of certain cancers, Newton said.
