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Feed production methods to reduce emissions, sequester carbon

Progressive Dairy Editor Karen Lee Published on 07 October 2021
Reduced tillage

Feed production amounts to roughly a quarter of dairy’s overall greenhouse gas footprint.

“Much of that is related to nitrous oxide emissions from the field after manure or nitrogen fertilizer is land-applied,” explains Karl Czymmek, vice president, agronomy and field sciences at Dairy Management Inc. (DMI).

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Field practices to reduce greenhouse gas (GHG) emissions is part of the equation for this aspect of the Net Zero Initiative, while the other focus is on carbon sequestration and improving soil health.

Certain practices can be utilized now, while others need more research and development. In addition, market opportunities are emerging to monetize these efforts.

As nitrogen from livestock manure or commercial fertilizer is converted to plant available nitrate, nitrous oxide may be formed. Once nitrate is formed, it can be converted to nitrous oxide at any time, depending on conditions. This means any extra nitrogen not needed to support crop production can add to nitrous oxide losses.

“A little bit of nitrous oxide lost on a lot of acres starts to add up because it is a potent greenhouse gas,” Czymmek adds.

According to the EPA, nitrous oxide has a global warming potential almost 300 times that of carbon dioxide.

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Applying nitrogen in the most effective way possible using the 4Rs of nutrient stewardship (right source, right rate, right time and right place) is an important practice toward reducing nitrous oxide emissions from the field, and it can be implemented on farms now.

When it comes to sequestering carbon, reducing tillage is an important practice; however, Czymmek says there are legitimate reasons why some dairy producers are hesitant to adopt no-till practices.

“Strip till is a nice intermediate way,” he says. “You can get a lot of the benefits of reduced soil loss and retention of carbon with a strip till system.”

In addition, he likes to tell producers they don’t need to make major cropping system changes on 100% of the farm in a single year.

“Experiment a little bit with some reduced tillage, and talk to somebody that may be doing it,” Czymmek recommends. “Start looking for some of these practices that aerate the soil less and find other ways to leave more residue in the ground or on it.”

“One of the most exciting things about the field aspect of things is the opportunity not only to reduce our greenhouse gas emissions – particularly nitrous oxide – but it’s also to sequester carbon,” Czymmek says. “So, really pull carbon out of the air and keep it in the soil.”

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Cover crops, even if harvested in the spring, provide living roots through the winter that add carbon to the soil along with other benefits. Perennial cover and crop rotation practices for dairy forage crops can also sequester carbon.

In addition, these regenerative agriculture principles lead to long-term soil health and increased organic matter.

“Organic matter can hold close to its own weight in water. If you have more tons of organic matter across an acre, it will hold more water,” Czymmek says.

More water retention reduces soil erosion, flood risks, crop stress and irrigation need.

“Those are really basic things for improving soil health,” he says. “Even on dairy farms where you’ve had manure and we’ve had really good crop rotations, there’s more we can do to build on what we’ve done over the last decades.”

Research underway

There remain some unknowns on the measured impact of these strategies toward reducing GHG emissions, sequestering carbon and improving soil health. High variability has been reported based on location, soil type and many other factors.

In June, the Foundation for Food & Agriculture Research (FFAR) awarded a $10 million grant to the Dairy Research Institute (DRI). Funding and in-kind support from Net Zero Initiative partners brought the total value of the Dairy Soil Water Regeneration project to $23.2 million.

The research for this project will be executed across four dairy regions responsible for about 80% of U.S. milk production. Eight regional farms, including five operating dairies, two university research dairies and one USDA-ARS research farm, are participating in the project.

“We’re working very closely with farmers, research partners and the Soil Health Institute in a five-year project, where we are implementing a range of soil health management practices,” Czymmek explains.

The objective is to monitor changes in greenhouse gas emissions, soil carbon storage, soil health and water quality to identify differences regionally and from treatment to treatment.

Some of the research within the project includes measuring and monitoring both tile drainage and surface runoff for water quality issues, water use with reduced tillage and other soil health practices, comparing full-width tillage practices to conventional liquid dairy manure applied in a strip till or no-till scenario, using new solids-based manure products surface-applied and in strip till situations, and nitrogen rate studies with the new manure products.

“This will give us really important information that we’ll share with farmers as the information unfolds about the different types of conservation practices, cover crops, new manure types of products and their impacts on greenhouse gas emissions and also this carbon sequestration concept as well,” Czymmek says.

Market opportunities

There is a lot of discussion taking place in how to monetize some of these practices in the areas of carbon sequestration, carbon trading and carbon credits.

“We think there’s real opportunities on ag land, both on dairy farms and land that is used to grow crops that are purchased by dairies, to sequester carbon and contribute to the overall effort for dairy to be an environmental solution,” he says.

Newtrient, a business collective of the national checkoff (DMI), the dairy farmer policy organization (NMPF) and leading U.S. dairy cooperatives, is working closely with Ecosystem Services Market Consortium (ESMC), a nonprofit group set up to explore the carbon market and monetization fees.

Future practices

Additional solutions to reduce emissions and improve carbon sequestration have been identified but are not yet ready for industry adoption.

“Some of the longer-term thinking is going to be on the crop side, ways to increase the amount of carbon that our plants are putting in the soil, adding to the root system and then finding ways to protect that root system and keep it in the soil longer,” Czymmek says.

The Salk Institute is researching gene-edited seeds for cover crops with roots that are more resistant to breaking down. Long-lasting roots will keep more carbon in the ground for greater carbon sequestration.

Hydroponic fodder production systems are showing potential for feed production with a minimal environmental footprint. Fresh livestock feed is grown in a controlled environment using 92% less water, less land, less energy and less labor when compared to traditional growing methods.

A case study published in Canada estimated hydroponically grown sprouted barley produced 7.4% fewer GHG emissions (per nutrient mass) than were found with conventional barley grain fodder farming.

Biochar is an option for long-term carbon storage. It is created through the pyrolysis of plant residues or dairy manure fiber. Carbon contained in the biomass is permanently bound though pyrolysis. Issues related to the equipment and scaling for larger processing need to be overcome before this can be implemented on a large scale, Czymmek says.

Manure-based fertilizer products could allow for more precise application of nutrients with minimal soil disturbance while improving soil health. The production of these products requires advanced manure treatment and technologies.

With the potential to reduce nitrous oxide emissions and sequester carbon, implementing these practices now and in the future will enable dairy farms to be more efficient in feed production and improve soil health.  end mark

ILLUSTRATION: Illustration by Kristen Phillips.

Karen Lee
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