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New reports outline science gaps for ‘regen ag’, soil health and climate change
People are increasingly aware of the current food system’s role in the planet’s climate change crisis. Regenerative agriculture has been proposed as an opportunity to slow and adapt to climate change.
Four reports, released today, outline possible approaches to test whether regenerative agriculture can indeed offer ‘nature-based’ solutions for climate change in New Zealand.
Nature-based solutions to climate change include increasing soil carbon stocks, increasing the resilience of farmland to flood and drought conditions, and reducing greenhouse gas emissions from agriculture. All these possible environmental benefits ultimately come from nurturing healthy soils.
The four reports include an overview of the main facts about agricultural greenhouse gas emissions and soil carbon storage, the different claims for how regenerative agriculture could mitigate greenhouse gas emissions, and the knowledge on which each claim is based. Each report outlines the science gaps still to be closed.
Soil health and greenhouse gas reduction potential
New Zealand’s greenhouse gas emissions are heavily influenced by agricultural activities, which account for 48% of total emissions. Most of these emissions come from methane from animals, followed by nitrous oxide emissions from soils (mostly associated with urine deposited by animals and fertilisers).
Soil and plants (particularly trees) also influence net greenhouse gas emissions through carbon capture and release. Increasing soil carbon stocks has been proposed as one way to reduce atmospheric carbon dioxide concentrations.
“New Zealand soils have high soil carbon compared to many other countries, but from a greenhouse gas perspective it is change in soil carbon stocks that is important,” says Dr Paul Mudge, portfolio leader for climate change adaptation and mitigation at Manaaki Whenua – Landcare Research, and a key contributor to the report Determining the greenhouse gas reduction potential of regenerative agricultural practices.
“There is good evidence that changes in land use in New Zealand can increase or decrease soil carbon stocks, and research is now looking at whether specific management practices have a big impact on soil carbon stocks.”
The report examines the four main claims made about how regenerative agriculture could reduce net GHG emissions:
- Regenerative agriculture soils are a greater sink for carbon than other agricultural soils
- Increased plant diversity with better nutritional quality leads to a reduction of methane emissions from animals
- Regen soils have high methanotrophic capability (methane-consuming microbes)
- Regen soils produce less nitrous oxide
Assessing whether regenerative agriculture creates healthier soils that could provide such benefits is difficult and several knowledge gaps remain, says Dr Nicole Schon of AgResearch, lead author of the Soil health research in the context of regenerative agriculture report.
“Soils are living systems and are inherently complex. This, combined with the diversity of soils and the complexity of farm systems, does not make addressing these knowledge gaps easy,” says Dr Schon.
Soil is increasingly considered a ‘common good’, like water and air. In Aotearoa New Zealand, we also need to consider principles integral to understanding soil health from a Māori perspective, considering that Māori have had a long connection to and understanding of soil. These include: mauri, mana, mahinga kai and māra kai, and oranga ora.
The soil health report proposes a core list of soil health indicators applicable to New Zealand soils, including measures suitable for on-farm monitoring, as well as for research purposes, and includes indicators commonly used by regenerative agriculture practitioners. The indicators listed go beyond standard soil fertility tests commonly used on-farm, and include organic matter properties, soil physical condition, and biological properties.
Adaptation to climate change
Soil has physical properties that affect its ability to retain water in periods of drought, and drain water in times of extreme or prolonged rainfall. Regenerative agriculture practices have been suggested to manage soil to increase resilience to flood and drought conditions, which are expected to increase in frequency and intensity over the coming decades.
The report Quantifying resilience to drought and flooding in agricultural systems proposes a series of soil health measurements to understand the impact of regenerative management practices on resilience (including soil macroporosity, infiltration rates, aggregate stability, soil carbon, plant cover, nutrient availability, and food webs). Using remote-sensing measurements from satellite is also proposed.
The fourth report, Ecosystem-based solutions for climate change adaptation in rural landscapes of New Zealand, describes additional ways that nature can support farm systems to adapt to a future under climate change. Pastures that are more diverse, for example, or farming systems that include trees and shrubs, would promote plant communities that are more stable and resilient to climate extremes.
This report outlines opportunities that might arise from adopting regenerative agriculture. Could ‘regenerative’ farming systems be more likely to evolve new ways to adapt to increasing pressure from climate change, or better nurture New Zealand’s unique flora and fauna in a future climate?
Expert Reaction
These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.
Professor Louis Schipper, University of Waikato
The report "Determining the greenhouse gas reduction potential of Regenerative Agricultural practices" provides a comprehensive examination of what is known and unknown about possible changes in soil carbon due to changes in land management.
The authors clearly demonstrate the gaps in our current knowledge and propose some useful experimental approaches for making advances.
A major challenge for research is that regenerative agricultural embrace a combination of different practices and determining which of these practices either together or individually are best for the soil and farming is challenging. As the authors recommend likely the best way forward is careful co-development of research plans between farmers and scientists.
Professor Amanda Black is Co-Director Bioprotection Aotearoa, Centre of Research Excellence.
"The concept of regenerative agriculture as it is used in this repurposed Aotearoa context still remains vague in its definition and potential use and even less clear how it would translate into practice for farmers to produce the benefits that these reports claim can occur.
There seems to be much re-packaging of existing concepts and definitions. As a scientist and one that works with Māori communities, these groups are already working towards increasing the health of the whenua, through kaitiakitanga, by working within the limits of the land especially soil. I would have liked to see actual examples of peer reviewed research on regenerative agriculture in practice that can clearly articulate the mechanisms which are enhanced by this practice, that produce the benefits that are claimed. A lack of definition coupled with a lack of peer reviewed research make it difficult to determine what can actually be realised from adopting this concept.
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