Greening the Dairy Industry

From methane reduction to water efficiency, David Pearce and Peter de Jong look at how dairy farmers and engineers are paving the way for a greener future

IMAGINE you are a dairy farmer. It is 6:45 on a cool, spring morning. You have just moved the cows out of the milking shed and you are looking forward to that next warm drink. As you gaze out over the verdant pastures, you notice a light going on in your house and wonder if your children will be drawn to farming the same way that you are. Early starts, long days, the pleasure of knowing that your milk provides essential nutrition to people all over the globe. They have seen the news items and social media posts and are already asking those awkward questions that children love to ask: “So Mum, what are YOU doing to save the planet?”

Multiple concerns

It is not just the next generation that is putting the squeeze on. Public pressure and an increased awareness of “greenwashing” is encouraging farmers and dairy companies to focus their spending on projects that will make a significant difference to the environment. However, dairy farmers view sustainability through multiple lenses:

• How can I improve the performance of the farm with fewer inputs (lower water and energy use, less fertiliser)?
• How can I lower waste from the cows?
• How can I leave the environment in a better state than I found it?
• Will I survive the current (or next) financial crisis?
• Will there still be a farm to pass on to the next generation and will the industry survive?

On-farm advances

On-farm emissions accounted for more than 80% of the greenhouse gas (GHG) emissions reported by Fonterra and Arla Foods in 2023.^1,2

Cows generate methane from the presence of methanogens in their digestive systems. Methane is a key greenhouse gas and efforts are underway to either reduce the emissions at source (through feed supplements) or capture the methane for processing when the cows are indoors. It has been estimated that every hour, a cow produces, on average, enough methane to fill a child’s party balloon. This concentration in fresh air is too dilute to make in-pasture methane collection practical. Collection of methane in buildings (barns and milking sheds) is more practical and is part of a Dutch Ministry of Agriculture, Fisheries, Food Security and Nature roadmap targeting a 50% reduction of GHG of milk.³

Methane reduction is only practical when the cows remain healthy and productive. Any methane reduction feed additive needs to pass a set of criteria before it can be considered.

It must be scalable and good for the:

• cow
• milk/food (no residues)
• farmer (economical and must fit in the system)
• planet (not wasteful to make)

New Zealand has formed the public-private partnership AgriZeroNZ which is investing in a number of promising methane reduction technologies including seaweed extracts as feed supplements. Trials conducted at CERZOO, the dairy farm of Università Cattolica in Italy, demonstrated that feed supplements decrease a cow’s methane emission by 20–30% and higher. The presence of any fat-soluble active ingredient needs to be carefully traced through the cow so it doesn’t end up in the milk.

Dutch company DSM has developed a feed supplement (3-NOP) that helps reduce bovine methane emissions. However, here New Zealand/European farm practice differences become clear. Supplement feeding in NZ’s pasture system is more difficult to control – the cows wander across paddocks and graze where they will. If a supplement’s effective half-life is less than the milking frequency, then it adds significant expense to farmers’ costs and is less likely to be considered. European farmers have the advantage of controlling feed intake during the winter months, making this sort of supplement more practical. New research has indicated that it is also possible to reduce emissions by using herb-rich grasslands.⁴

Cow manure can be fermented to (ironically) make methane as a fuel source. Again, this is more suited to high concentrations of cows in barn-raised systems or, in a pasture system where several farms pool their manure. There are pitfalls if adequate precautions are not taken, as seen in April 2023 when around 18,000 cows were killed in a gas explosion at a Texas dairy farm caused by an engine fire.

Another notable initiative is the investigation of climate-neutral agrifood systems in the province of Groningen, the Netherlands, which began in 2021. This ongoing research programme, called Fascinating, is exploring sustainable agricultural practices, and is seen as a model for the rest of Europe. The farm of the future, they say, revolves around four key strategies: healthy soil, high-quality nutritious crops, a sustainable and circular agricultural system, and a good earning model for farmers.

Targeted use of fertilisers is attracting attention too. Farmers are assessing new technology options to optimise use and to minimise any run-off and leaching to the ground water. In New Zealand there are two initiatives that are worth mentioning. FPA NZ has developed an improved distribution system for solid fertiliser – Fine Particle Application – which improves fertiliser efficiency and performance through greater surface coverage of fertiliser on the ground. Their fertiliser delivery system avoids isolated build-ups of granules which can lead to fertiliser burn caused by high nutrient concentrations.

Meanwhile, Pastoral Robotics has developed a system for detecting cow urine patches in the pasture. This makes tailoring fertiliser addition to avoid these patches, or targeted application of nitrification inhibitors possible.

These and other on-farm efforts are assisted by customer pressure on food producers. In New Zealand, milk supplier Synlait Milk and dairy cooperative Fonterra have entered into agreements with Nestlé and Mars to reduce on-farm emissions. In the Netherlands, supermarkets are pressuring private dairy producers and cooperatives to incorporate more plant-based ingredients into their products. This trend is driven by the slower-than-expected growth of the milk alternatives market, which has been hampered by disappointing taste and health benefits. Consequently, retailers are urging producers to diversify their offerings to better meet changing consumer preferences.

Chemical engineers can make big impacts in other areas of on-farm operation including water recovery and reuse and effluent processing. Of particular interest is where process intensification and unit operation scaledown principles can be applied. For example, cost effective small-scale membranes for water recovery and reuse and innovative effluent processing. Farmers can only bear a limited capital investment so clever solutions in this area will be very beneficial. Electricity use can be reduced by using smart energy meters (energy use monitoring), heat pumps, solar energy integration and energy storage using hot water or batteries. There is also a place for using better sensor technology to minimise water use and accidental discharges.