Land-use change for healthy New Zealanders and a healthy environment

Journal of the Royal Society of New Zealand (2022). DOI: 10.1080/03036758.2022.2137532″ width=”800″ height=”530″/>

Schematic description of the process followed to create and test the two scenarios for achieving a healthy diet. credit: Journal of the Royal Society of New Zealand (2022). DOI: 10.1080/03036758.2022.2137532

Changing what we grow and where can provide all New Zealanders with a healthy diet with benefits for our water, climate and national economy, new research from two national science challenges finds.

The range of food we grow in Aotearoa and where we grow it is likely to change in the coming years due to the changing climate and our responsibility to restore the health of our water and atmosphere. New research from two national science challenges, published today, tested future scenarios for this land-use change to see if it’s possible to craft a win-win plan for future food production.

Can we produce the right crops, in the right places, to feed all New Zealanders a healthy diet, while reducing greenhouse gas emissions or freshwater pollution and minimizing the financial impact on families and farmers?

The short answer is yes, says Professor Richard McDowell, lead author of the report and chief scientist for the Our Land and Water National Science Challenge. “By redirecting land use in parts of Aotearoa that are unlikely to meet water quality targets without land use change, we could achieve our environmental goals,” says McDowell.

Producing a home-grown healthy diet for all New Zealanders would mean growing more grains and vegetables. The study used a range of crops such as oats, beans, peas, potatoes, onions, wheat and barley as “indicator” crops, McDowell says. “In the real world, a more diverse range of crops would need to be grown for our healthy diet, but we chose these crops to show that this wider range can be grown.”

The projected effect on farm profits varies depending on whether the future scenario is optimized for water quality improvement or greenhouse gas reduction, ranging from a net loss of $526 million nationwide for the freshwater-focused scenario to a gain of $89 million for a climate-focused scenario, bolstered by returns of up to $2.4 billion from larger arable land, horticulture and forestry sectors. The change in land use is not expected to seriously affect our export trade in red meat and dairy products.

“The maximum cost was about 1% of primary sector export earnings, with the potential for billions of dollars in savings to the health system if we all adopted the healthy diet modeled in this paper,” says McDowell.

The research is “a modeling exercise and a thought experiment”, McDowell says, and whether the scale of both land use and dietary change is feasible in practice depends on the decisions of all New Zealanders. “The key takeaway is that it is possible to strategically redesign New Zealand’s future food production in a way that has significant co-benefits for our people and our environment.”

“Land-use change in Aotearoa is inevitable as new opportunities and challenges arise in a changing climate. In watersheds where water quality expectations are driving change, land-use diversification may be more pragmatic than investing in all possible mitigation measures,” says McDowell.

“It makes sense to take a strategic, planned approach to maximizing the benefits of this land-use change. This research offers a starting point for those discussions.”

The healthy diet

A diet optimized for nutrient intake, greenhouse gas emissions and food prices for New Zealand was published in a separate paper last month.

The optimized diet meets 24 nutrient recommendations, produces greenhouse gas emissions that are below the limit set for New Zealand and costs no more than the baseline cost from the last National Nutrition Survey in 2008/09.

“This shows us that we can improve people’s health while reducing greenhouse gas emissions from food production,” said Christina Cleghorn, lead author and principal investigator of the Healthier Lives National Science Challenge.

National adoption of this diet has been modeled and has shown major health benefits, cost savings to the health system and reduced health inequalities between Māori and non-Māori. “We know that this diet differs from what people are currently eating and more research is being done to identify a more realistic healthy and sustainable diet for New Zealanders,” says Cleghorn.

In this new study, that diet was modified to include slightly more beef, lamb and dairy.

Changes in land use

To identify suitable land for producing ingredients for this diet, the research uses crop suitability maps and aims to expand current production areas by 2035.

These cards were used in two scenarios. The climate-focused scenario focuses on reducing greenhouse gas emissions by removing up to 13% of stock (as outlined by the Commission on Climate Change) and replacing dairy land with crops and sheep and beef systems with forestry. The freshwater-focused scenario allowed crops and forestry to expand in all grassland farming systems until nitrogen and phosphorus losses were low enough to reduce algal growth in rivers, lakes or estuaries.

The research targeted this expanded crop production to land areas that had been identified as likely sources of pollutants causing unacceptable levels of algal growth. This is 3.8 million ha for land with excess nitrogen losses and 2.3 million ha for phosphorus.

After accounting for crop rotations, land use change equates to an increase in arable land of 29–32% (on land suitable for growing crops or horticulture) and an increase in forestry of 82–138% (on land not is suitable for growing crops). To accommodate this expansion of arable land and forestry, sheep and beef land will decrease by 11–19%, while land used for dairy production will decrease between 7–14%.

However, the impact on export earnings was expected to be minimal if the previous increase in productivity was maintained. The open access paper includes national maps and an analysis of the regional effects of these changes, as well as a discussion of the limitations and implications of this research.

The study was published in Journal of the Royal Society of New Zealand and sustainability.

More info:
Richard W. McDowell et al, Farming for good: producing a healthy, low-GHG diet and water quality in Aotearoa, New Zealand, Journal of the Royal Society of New Zealand (2022). DOI: 10.1080/03036758.2022.2137532

Christine Cleghorn et al, Assessing the health and environmental benefits of a New Zealand diet optimized for health and climate protection, sustainability (2022). DOI: 10.3390/su142113900

Courtesy of Our Land and Water National Science Challenge.

Quote: Land use change for healthy New Zealanders and a healthy environment (2022, 25 November), retrieved on 25 November 2022 from https://phys.org/news/2022-11-land-use-healthy-zealanders- environment.html

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