Professor and Chair in Lake and Freshwater Sciences, University of Waikato
Climate Explained is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change.
If you have a question you’d like an expert to answer, please send it to firstname.lastname@example.org
I would like to know to what extent regenerative agriculture practices could play a role in reducing carbon emissions and producing food, including meat, in the future. From what I have read it seems to offer much, but I am curious about how much difference it would make if all our farmers moved to this kind of land management practice. Or even most of them. – a question from Virginia
To identify and quantify the potential of regenerative agriculture to reduce greenhouse gas emissions, we first must define what it means.
If regenerative practices maintain or improve production, and reduce wasteful losses on the farm, then the answer tends to be yes. But to what degree is it better, and can we verify this yet?
Let’s first define how regenerative farming differs from other ways of farming. For example, North Americans listening to environmentally conscious media would be likely to define most of New Zealand pastoral agriculture systems as regenerative, when compared to the tilled fields of crops they see across most of their continent.
If milk and meat-producing animals are not farmed on pasture, farmers must grow grains to feed them and transport the fodder to the animals, often over long distances.
It’s hard to miss that the transport is inefficient, but easier to miss that nutrients excreted by the animals as manure or urine can’t go back to the land that fed them.
Returning nutrients to the land really matters because these build up soil and grow more plants. We can’t sequester carbon in soil without returning nutrients to the soil.
New Zealand’s style of pastoral agricultural does this well, and we’re still improving as we focus on reducing nutrient losses to water.
First, the animals that efficiently digest tough plants – including cows, sheep, and goats – all belch the greenhouse gas methane. This is a direct result of their special stomachs and chewing their cud.
Therefore, farms will continue to have high greenhouse gas emissions per unit of meat and milk they produce. The recent Intergovernmental Panel on Climate Change (IPCC) report emphasised this, noting that changing diets can reduce emissions.
The second problem is worst in dairying. When a cow lifts its tail to urinate, litres of urine saturate a small area. The nitrogen content in this patch exceeds what plants and soil can retain, and the excess is lost to water as nitrate and to the air, partly as the powerful, long-lived greenhouse gas nitrous oxide.
Regenerative agriculture lacks a clear definition, but there is an opportunity for innovation around its core concept, which is a more circular economy. This means taking steps to reduce or recover losses, including those of nutrients and greenhouse gases.
Organic agriculture, which prohibits the use of antibiotics and synthetic pesticides and fertilisers, could potentially include regenerative agriculture. Organics once had the same innovative status, but now has a clear business model and supply chain linked to a price premium achieved through certification.
The price premium and regulation linked to certification can limit the redesign of the organic agricultural systems to incremental improvements, limiting the inclusion of regenerative concepts. It also means that emission studies of organic agriculture may not reveal the potential benefits of regenerative agriculture.
Instead, the potential for a redesign of New Zealand’s style of pastoral dairy farming around regenerative principles provides a useful example of how progress might work. Pastures could shift from ryegrass and clover to a more diverse, more deeply rooted mix of alternate species such as chicory, plantains, lupins and other grasses. This system change would have three main benefits.
The first big win in farming is always enhanced production, and this is possible by better matching the ideal diet for cows. High performance ryegrass-clover pastures contain too little energy and too much protein. Diverse pastures fix this, allowing potential increases in production.
A second benefit will result when protein content of pasture doesn’t exceed what cows need to produce milk, reducing or diluting the nitrogen concentrated in the urine patches that are a main source of nitrous oxide emissions and impacts on water.
A third set of gains can result if the new, more diverse pastures are better at capturing and storing nutrients in soil, usually through deeper and more vigorous root growth. These three gains interrelate and create options for redesign of the farm system. This is best done by farmers, although models may help put the three pieces together into a win-win-win.
Whether you’re interested in local beef in Virginia, or the future of New Zealand’s dairy industry, the principles that define regenerative agriculture look promising for redesigning farming to reduce emissions. They may prove simpler than agriculture’s wider search for new ways of reducing greenhouse gas emissions, including genetically engineering ryegrass.