Livestock producers may need to adapt their feedbase to reduce methane and nitrous oxide emissions and satisfy investors. Image shows chicory and lucerne established in subclover/ryegrass pastures.
Since the Paris Agreement in 2015 to limit global warming, supply chains have responded to pressure from institutional investors with an increasing need for sustainability and climate action. Now, multinational agribusinesses are launching Carbon Neutral (CN) strategies, where outputs are produced with lower greenhouse gas emissions and remaining emissions are offset with carbon sequestration projects.
According to Professor Richard Eckard from the Primary Industries Climate Challenges Centre at the University of Melbourne, these companies are causing a cascade of change down the supply chain and making government targets for climate action in agriculture a moot point.
Professor Eckard spoke at the recent Ag Excellence Virtual Forum where he began by describing some examples of international drivers behind carbon neutrality that farmers need to know about. These include the launch of Carbon Neutral Brazilian Beef, a brand making inroads into European markets and influencing MLA’s CN30 target. Perhaps more challenging is the move of dairy processors such as Danone towards plant-based food and drinks.
There is no doubt that ruminant-based products are the most exposed agricultural industry due to the associated methane production. This has resulted in some operations announcing CN brands, although not through reducing emissions, but instead by buying carbon offsets from tree-planting projects. However, Professor Eckard believes producers can reduce their emissions without losing productivity.
Before discussing how emissions can be reduced, Professor Eckard looked at the carbon cycle in agriculture to explain its impact. He said that agriculture is in the business of carbon farming because it takes carbon dioxide (CO2) out of the atmosphere and converts it to plant carbohydrates. Most of this carbon returns to the atmosphere either directly from plants, via ruminants and humans eating plants or meat, or through the soil when crop residues break down and are mineralised (with some possibly staying in the soil).
“If that is where it stopped the system would be largely carbon neutral. However, a small amount of those emissions from the cow is in the form of methane. That small amount of methane does warm the atmosphere and we need to find ways to put it back to CO2 or stop it from being emitted.”
In addition to methane, nitrous oxide is another significant agricultural emission. Professor Eckard looked at what could be done to reduce both these gases and how any remaining emissions could be offset to achieve carbon neutrality.
Methane
Methane production, which represents 10% of Australia’s national emissions, is a function of how long the fibre stays in the rumen of an animal. So, by improving digestibility and passage rate through the animal we can reduce the amount of methane. Secondary compounds like tannins in feed can also reduce methane.
“We can feed animals on more digestible forages and introduce legumes (relatively digestible) which contain tannins to reduce methane by 10-15%. We also know that feeding supplements like grape marc, a waste product from the wine industry that contains tannins can reduce methane by about 20% (but may reduce productivity).”
“We can also improve the management efficiency with better herd health and fertility which can reduce methane by about 10%.”
Other options are quickly emerging, including asparagopsis seaweed and 3-NOP that inhibit methane production. Feeding these out will be easiest in confinement industries (e.g. feed lots) and can reduce methane by up to 80%. 3-NOP is expected to be available for commercial use by the end of 2021 (although perhaps in 3-5 years for non-confinement industries).
Other initiatives that may provide alternatives in the future include a vaccine program in New Zealand, a ZELP (zero emissions in livestock) device that hangs around the cows neck and oxidises methane as it is breathed out, and “early life programming”, where animals are weaned onto a low methane diet and appear to emit less methane as they age.
“There are solutions coming through, so I think we need to be encouraged by research that is delivering solutions that weren’t dreamed about ten years ago.”
However, more work is required to develop carbon farming methodologies or more sophisticated carbon accounting platforms that measure or model reduced emissions from most of these changes.
Nitrous oxide
Nitrous oxide (N2O) is another greenhouse gas produced in agriculture, representing 3% of national emissions. Nitrous oxide emissions increase when there is too much unutilised nitrogen in our system and can be improved with nitrogen use efficiency.
“As we increase the rate of nitrogen we apply, we get to a point where there are diminishing returns. We’re not getting more crop or pasture production. But as you exceed what the soil-plant system needs, there is an exponential increase in the amount of N2O going to the atmosphere.
“There are slow release products that can reduce un-utilised nitrogen, but I would also suggest we need to get back to legumes again. Not just for methane (as explained above) but because legumes in rotations require less fossil urea and can slow down the nitrogen cycle in our systems.”
Unfortunately, livestock are a major source of N2O as well. The urine produced by our animals is 75-95% liquid urea.
“The best tool we have there is to feed our animals on a better mix of energy to protein. Getting the energy-protein ratio right (animals require sufficient energy to process protein) is our best tool at reducing excess urinary nitrogen loss from livestock.
“In terms of soil management, avoid saturated soils, address compacted soils, and avoid soil disturbance. Minimal disturbance is a critical factor in maintaining good soil organic matter and soil carbon, but it’s also critical not to stir up the nitrogen cycle in the soil and liberate too much organic nitrogen at one time.”
Trees
“To reach absolute neutrality, we will still need offsets in soils and trees.”
Professor Eckard says that trees need to be valued for their co-benefits because the carbon benefits seldom match the productivity lost from giving up land for trees.
“If you start valuing trees for their co-benefits, shade and shelter, lamb survival, salinity reduction, animal welfare, nutrient sinks on farm. A small amount of lamb survival will pay for trees on your western boundary if you are in southern Australia.”
Professor Eckard also warns against selling carbon credits outside of Australia or outside of your farm business, suggesting that a better use is to use it to offset your own emissions and not those from potential buyers.
“The day will come when you might want that offset against your own industry or your own personal liability and from a policy view that becomes quite important.”
For more information on emissions reductions, see https://agriculture.vic.gov.au/climate-and-weather/understanding-carbon-and-emissions/livestock-methane-and-nitrogen-emissions
To view the presentation, follow this link and watch the Plenary: Opening Keynotes recording from 1 Hour and 12 minutes. Note that soil carbon was discussed in a separate presentation by Dr Mark Farrell, which can be found as a separate recording on the same webpage.
Also read “A climate of opportunity in ag” based of presentations from Fiona Simson (National Farmers Federation) and Mark Howden (Australian National University) from the same Plenary session.
