When you have pasture-based systems and organic crop production, you have a smaller carbon footprint.
That’s how Nicole Rakobitsch puts it. Rakobitsch is director of sustainability at Organic Valley, the largest organic dairy cooperative in the United States, and also part of a University of Wisconsin-Madison research team behind a first-of-its-kind study.
The peer-reviewed research uses a “breakthrough methodology” that includes accounting for the carbon sequestration benefit of grazed pastures.
The work was published in the Journal of Cleaner Production and included a dairy lifecycle assessment conducted on Organic Valley farms. The reported findings: Small organic farms, which focus on grazing and organic production techniques, are “low greenhouse gas champions,” Organic Valley says.
Which may be udderly fascinating, but not super surprising.
The pasture benefit on GHG (greenhouse gas) emissions is explained by two factors, says lead researcher Horacio Aguirre-Villegas, Scientist III at the University of Wisconsin-Madison.
First, pasture systems have a more developed root system than other crops fed to cows.
“So, with pasture, you are leaving the majority of the biomass (and thus carbon) on the soil, versus corn, where you are taking most of the biomass out of the farm,” Aguirre-Villegas says.
Part of this biomass in the roots is carbon, and part of this carbon will be stored in the long term (more than 100 years), based on different factors.
“We captured this benefit by incorporating carbon sequestration in our analysis. The extend of the carbon sequestration benefit depends on different factors, such as how much carbon stays on the soil above, below ground and from manure, and the region,” he says.
The second benefit from pasture systems is that the feed is produced where cows eat, Aguirre-Villegas says. “So, there is no need for transportation, storage, harvesting, etc., meaning less use of inputs and thus, related GHG emissions.”
Beyond being the biggest cooperative of its kind in the U.S., Organic Valley is also one of the world’s largest organic consumer brands, representing nearly 1,800 farmers in 34 U.S. states along with Canada, Australia and the United Kingdom.
How does organic farming contribute to carbon sequestration?
The organic farms modeled in the study all receive at least 50% of their diet requirement with pasture or grass forages, Aguirre-Villegas explains.
Organic dairy farming in general requires less use of resources such as synthetic fertilizers and feed supplements. These resources don’t need to be manufactured, which equals less GHG emissions.
How low is low when it comes to reduced greenhouse gas emissions from organic farms?
The study says carbon sequestration benefits range from 7 to 20%.
“This really depends on the farm system,” he says.
Conventional farms could adopt very efficient and sustainable management practices, such as anaerobic digestion from manure, injection of nitrogen fertilizers, cover crops, follow nutrient management plans to avoid nitrogen losses and have reduced GHG emissions.
“The range can be wide.”
As for the milk produced by the cows, a 2013 national study of conventional dairy farms found more milk produced on average than the University of Wisconsin-Madison study of organic farms (termed as fat and protein corrected milk). However, neither study included carbon sequestration in their analysis, Aguirre-Villegas says.
“Carbon sequestration is a complex mechanism that depends on many variables, and perhaps one of the reasons why carbon sequestration is usually absent from life cycle assessment studies evaluating GHG emissions and other environmental impacts of agricultural systems,” he says.
“Our study proposes a method to include carbon sequestration in the analysis and we hope that other researchers use the method and if possible, improve it, so that this environmental service of farms that rely on grazing, is captured.”
And it’s not just organic farms that can benefit.
“All farms producing grass and other crops can adopt (the study’s proposed method),” Aguirre-Villegas adds.
“As a second part of our study, we also want to include additional environmental services that organic farms provide that might not be realized in these types of studies. For example, some farms have preserved forest land or wetlands in their farm, contributing not only to further sequestration or carbon but to air and water quality.”