“Dairy farms do have some impact on climate change. Dairy farms do emit greenhouse gases (GHG). And, of course, the changing climate impacts dairy farms,” Al Rotz, USDA-ARS, said.
Carbon dioxide is the “major driver” of climate change, with methane also a concern. But most methane emissions come from the natural gas industry, not agriculture, he said. Of those methane emissions coming from agriculture, enteric rumination is the primary source.
Nitrous oxide is another emission of concern coming from dairy farms, primarily from feed crop production via use of fertilizers and manures.
No matter the origin of GHG, the impact of climate change will be felt by dairy farmers on many levels.
By 2100, the climate in New York state will resemble that associated with Georgia in 1960, according to models released by the Union of Concerned Scientists, if emissions do not decrease, Rotz said. Variable weather patterns, generally warmer temperatures and overall changes in precipitation are anticipated.
Increased levels of CO2 will impact forage growth. Changes in planting and harvest dates of all crops will occur. Quality and quantity of feed will be affected. Types of feed crops planted will change. Animals will need to cope with added heat stress, and their nutrient requirements will change, too.
Adaptations on the farm level will be crucial to mitigate the impacts of this drastic change in weather patterns. Maintaining dairy farm productivity and profitability will require changes in management.
While climate change will cause changes in management, these changes in farm management practices also impact the climate. Attempting to quantify the results of any given change implemented – whether caused by climate changes or put into place to mitigate GHG emissions – is complicated.
“There are many interactions occurring throughout the farm. There is a ripple effect. Whether we are looking at mitigation or adaptation to climate change, we need to take this grand whole-farm perspective,” Rotz said. “We really need to take a more holistic or whole-farm approach to really look at and evaluate mitigation strategies.”
The Integrated Farm Systems Model (www.ars.usda.gov/main/docs.htm?docid=8519) is a tool to do just that. This model provides an overall look at the life cycle impact of all farm inputs as well as direct GHG emissions from the farm. It offers an integrated model to examine the farm’s overall carbon footprint, suggests where changes can be made and demonstrates how those changes resonate through the farm system.
Things like the carbon footprint of feed or fertilizer used on the farm, and fuel use and emissions from tractors and machinery, are included in this complex view. A long-term, 25-year view is typically completed, Rotz said.
Changes in manure management can make a big impact on GHG emissions. Using actual data from a New York dairy farm and simulating a change in its manure management practices has led to a comparison of four climate change mitigation techniques.
The four manure management strategies studied were: slurry storage with surface manure application, solid-liquid separation with the reclaiming of solids for bedding combined with open liquid storage with surface application and rapid incorporation, same solid-liquid system but with enclosed manure storage where the biogas is flared and the same solid-liquid separation system but with the addition of an anaerobic digester, used prior to separation and storage.
There was not a lot of variation in profitability over 25 years of simulated data. Enclosed storage was the most expensive when measured on an annual-cost-per-cow basis. Anaerobic digestion returned some money to the farm via energy savings, keeping it in line with open storage solid-liquid systems.
Covering manure storage, however, almost eliminated GHG emissions from manure. Anaerobic digestion and covered storage both demonstrated 20 percent reduction in CO2 emissions on a per-pound-of-milk basis, with the digester also decreasing the farm’s energy footprint per pound of milk produced.
Real farm experiences
New York farmer Skip Hardie of Walnut Ridge Dairy – a 2,000-acre, 1,400-cow operation – recently opted not to install an anaerobic digester on his dairy, taking another route to improve manure management and farm sustainability.
“We didn’t build a digester, and I thought we were going to,” Hardie said. “A digester would have diverted a scarce commodity on our farm, which is management. There was this (other) emerging technology that would solve our odor issue.”
Odor was a major issue on the farm. They were hauling liquid manure and not incorporating it. But although they had the capital to install an anaerobic digester, they opted instead to utilize a draghose and pump manure into the ground. Hardie’s advice to the dairy industry is to “stop being reactive and start being proactive.”
John Fiscalini of Fiscalini Farms in Modesto, California, did install an anaerobic digester on his dairy farm in 2007. Hot water from the digester is used to pre-heat water for the boiler, to heat the digester’s tank and is used as dairy washwater.
Fiscalini Farms was the first dairy to put in a digester following changes in California law, after the regional air quality and water commission boards were put in charge of dairy digester regulations. They encountered many impracticalities and hurdles.
“Digesters do one thing very well. They reduce the amount of waste coming out of a dairy farm,” but are difficult to manage, Fiscalini said. “Digesters are expensive to build. The consumer is going to have to be the one who is going to pay for this.”
Fiscalini triple-crops 460 out of the farm’s 530 acres. The farm has installed all LED lighting, put acrylic coating on the roofs and variable-drive motors on equipment.
“The farm has to be at the center of the research and development,” for climate change solutions, New York dairy farmer Doug Young said.
Young advocates for Farm Smart (farmsmart.usdairy.com/about), which is an Innovation Center for U.S. Dairy program and “is like a nutrient program for the whole farm. It allows a farmer to look at the whole resource system,” he said.
Young installed an anaerobic digester last year, after 20 years of research and at a cost of $1.8 million. He has found it to be very efficient, and it was 40 percent less expensive than any of his other alternatives. His farm is also improving nutrient management, experimenting with nutrient boom designs.
“They’ve got to solve the problem, and they’ve got to be profitable,” Young said of options for improving environmental concerns. “Moving from a concept to a practical operating system” is challenging.
Moving ahead, dairy farmers are urged to proactively take measures on the farm to reduce their contributions to climate change and to adapt to the challenges brought about by climate change in ways that work for their farm system.
“We can adapt pretty easily and maybe even improve our systems, improve profitability, as we move toward this climate change,” Rotz said. PD
Al Rotz’s presentation, along with the farmer panel presentations, were presented at the Dairy Environmental System and Climate Adaptation Conference in July 2015, at Cornell University.
Tamara Scully, a freelance writer based in northwestern New Jersey, specializes in agricultural and food system topics.
ILLUSTRATION: By Kristen Phillips.