California dairyman Andy Rollin reduces air emissions and improves dry matter recovery by covering silage with an oxygen barrier film and plastic.
California dairies must cut silage emissions
Andy Rollin’s farm is one of 900 California dairies that must pay extra attention to silage management as a result of newly expanded air-quality laws.
Rule 4570 requires San Joaquin Valley dairies and other confined animal facilities (CAFs) to adopt additional management practices to reduce air emissions, not just from manure handling and storage but also from silage.
Officials with the San Joaquin Valley Air Pollution Control District revised the air-quality rule last October. The vast valley has some of the nation’s worst air quality.
The rule was amended after research conducted on California farms the past four years revealed that feed fermentation contributes more to smog-forming emissions than manure or cows.
Industry sources say it’s difficult to calculate the amended rule’s compliance costs since no two dairies operate the same and many already practice silage emission mitigation measures.
Rollin’s dairy is a good example. "We’ve already put a lot of the pieces together," says Rollin, who milks 2,000 cows with his father and brother near Riverdale, Calif. "Our management over the past four years has improved our silage quality and should help us comply with the amended rule."
Among its emission-cutting efforts, the Rollin dairy limits silage loss and shrinkage by compacting alfalfa, wheat and corn in high-density "rollover piles." The Rollins also harvest their feed at 64% to 66% moisture, giving them a 34% to 36% dry-matter level. "Higher than 70% results in poor fermentation and higher emissions," Rollin says.
In addition, the dairy uses an oxygen barrier film and plastic covering on silage to reduce spoilage. It also uses a quality inoculant that maximizes fermentation efficiency and improves the shelf life of open-face silage.
"We keep our silage pile as intact as possible," Rollin says. "The feeder shaves off only what we’re going to feed that day. In the end, the combination of all we’re doing will help us comply with the rule."
Rule 4570 offers a menu-driven system that allows producers to comply with both mandated and optional measures to cut down on emissions.
"The menu options are key because every dairy is set up differently," says Justin Gioletti, who milks 2,000 cows near Turlock, Calif. "Those choices have got to be there."
One option calls for dairies to bag their silage to curb emissions. "We’ve had 100% bagging for 10 years already," Gioletti says. "We have no silage piles at all. Last year, we started monitoring the packing density in our bags. We’ve made significant improvement in our feed quality."
Joey Airoso, who milks 2,500 cows near Pixley, Calif., says most dairy producers "don’t mind doing things that help the environment." He believes the revised rule balances environmental benefits along with improved feed operations.
"A lot of dairies are already doing the things required by 4570," Airoso says. "Twenty years ago, nobody covered their silage piles. Now, everybody’s starting to do it. There’s a cost, but also benefits: reducing shrink and keeping gases from being released."
Under Rule 4570, covering silage piles is mandatory. Dairies must increase silage bulk density and maintain an even silage face when removing silage from a pile or bunker. Many dairies already perform other requirements, such as pushing feed within 3' of a feed-lane fence and storing grain in a weather- proof storage structure or covering. Valley freestall dairies already pave their feed lanes at least 8' along corral sides.
"Producers are willing to do their part," says Paul Martin, environmental director of Western United Dairymen. "But they also see the need for sound science to back up the measures."
Of the valley’s 1,331 dairies, 900—those milking 500 or more cows—are subject to Rule 4570, says Sheraz Gill, supervising air quality engineer with the valley’s air district. Dairies represent about 70% of the valley’s CAFs.
The air district’s target is to reduce volatile organic compound emissions by 31.62 tons per day by 2023. "That will result in substantially cleaner air and help the valley come into attainment for ozone," Gill says.
California’s regulation-weary producers accept the new rule in part because it is based on management practices developed with input from dairy organizations, University of California scientists and other stakeholders.
"The science is getting better, with less focus on cows and more on silage," Gioletti says. "We hope for opportunities to make people aware of how to better pack their silage. The regulations aren’t going away. The way I look at it is: How can I get something positive out of this?"
A CLOSER LOOK AT RULE 4570
First adopted in 2006, Rule 4570 was designed to limit emissions of volatile organic compounds (VOCs) from confined animal facilities. VOCs are a precursor to regional ozone formation.
The revised rule requires SJV dairies to submit plans for emission mitigation measures by April 21, 2011. The San Joaquin Valley Air Pollution Control District has six months to approve or reject a dairy’s mitigation plan. If a dairy’s plan is approved, the air district will grant a “Permit-to-Operate.” Dairies have a year to implement their emission mitigation measures. The air district will review each plan every three years.
The SJV air district’s compliance department will enforce the rule. Producers must document their efforts, and air district employees will verify those measures with periodic visits to dairies.
“That’s no change to our previous practices,” the air district’s Sheraz Gill says.
Last October’s amendments also changed the size of dairies subject to Rule 4570 from 1,000 to 500 milking cows.
Dairies that don’t carry out the mitigation measures could receive a violation notice and be subject to a range of financial or operational penalties.
“The air district will work with dairies to get them into compliance as soon as possible,” says Gill.
- February 2011