July 6, 2005
Settling Dust Around Feed Yards a Matter of Management
AMARILLO "“ Cattle move, dirt stirs, dust rises "“ it's an inevitable part of the livestock industry.
But it's something feedlot management and researchers are working to minimize and control.
"We believe in our industry and want to be more progressive, to be better stewards," said Kevin Bunch at the Bar G Feedyard near Hereford during a recent tour by the Agricultural Air Quality Task Force.
"We have procedures and policies in place that are doable and we want to present these things to the legislature, so they see we are doing the things that should be done," Bunch said.
At Bar G, he said, dust is managed through frequent manure removal, as well as a sprinkler system.
Greg Sokora, a conservation service civil engineer from Lubbock, said the sprinkler system is designed to put out one-eighth inch of water per day across the yard. The system takes 2.5 hours to make a complete cycle through the yard, spending six minutes per pen. It rotates across the yard throughout the day, except for a short period in the afternoon, he said.
Computer controlled and based on golf course irrigation, the solid-set sprinkler system pumps 2,100 gallons per minute with 80-90 pounds per square inch of pressure at the nozzles, Sokora said.
Four such systems were installed in feed yards last year. This year is the first for monitoring and logging how much water is needed to keep the manure packed and somewhere between 20 and 30 percent moisture, he said.
Meteorological conditions "“ wind speed, temperature and moisture "“ are figured into the system, Sokora said, because "our water is very precious. As a general rule, we're going to stay as close to the dry side as we can."
The system should help keep odors down and can be used to help control flies by putting insecticides in with the water, he said.
Dr. Brent Auvermann, Texas Agricultural Experiment Station associate professor of agricultural engineering in Amarillo, said corn at its peak water usage takes more than one-half inch of water per day.
Comparatively, cool season data this year shows the sprinkler systems require less than one-quarter inch per day to replace evaporation from the feedlot surface, he said.
The solid-set sprinkler systems are one method of dust control; however, feed yard operators have found no one solution is right for every location.
Older yards that sprawl along the topography of the land are difficult to retrofit with solid-set sprinkler systems, Auvermann said.
A water curtain is an option for these yards where dust control may be critical, he said. A pilot-scale water curtain designed for a Hereford-area feed yard uses about the same amount of water, or less, as a sprinkler system to suppress dust at the corral boundary.
Spraying about 1-2 gallons per minute per foot, the 270-foot long, 43-foot high booms put out 300-320 gallons per minute of water each evening. That's when dust concentrations are highest and atmospheric conditions are stable, he said.
The prototype's effectiveness is being tested using monitors and samplers downwind, with initial results showing about a 40 percent reduction in dust concentrations, Auvermann said.
It is not advantageous to operate the water curtain in the afternoon when there is too much turbulence in the air or after midnight when the cattle activity drops off, Auvermann said.
In feed yards where the water is not available or sprinkler systems have not been installed, frequent manure harvesting is the key to dust control, he said.
For years, university agricultural engineers in Texas have advocated "harvesting manure" as a measure of dust control. Harvesting manure means scraping the pens in a way that will yield better quality manure, reduce mud, dust and odor, and improve pen drainage.
Manure harvesting scrapes the loose mixture of manure and dirt on top, but does not disturb the compacted layer underneath, Auvermann said. The goal is to leave a hard, smooth uniform and well-drained pen, he said.
Most beef feedlots conduct at least one annual pen cleaning, but the environmental incentive plan requires yards to make three manure harvests per year in order to qualify for cost-share payments, Sokora said.
Ben Weinheimer, Texas Cattle Feeders Association regulation manager in Amarillo, said for 20 years the industry has been sponsoring research to get to this point and is now working to build these programs.
"We're making big progress as far as dust control," Weinheimer said.
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