Guest Research Review: How does organic mitigate climate change?

by Kristen Howe, MES

Organic production does mitigate climate change. The question is not if, but how.

The Washington-based Organic Centre is one of the authors of a ground-breaking study that builds our understanding of just how this occurs. Working with hundreds of soil samples from organic and conventional farmers, the researchers found that on average organic soils are sequestering more carbon in a stable form that can be stored long-term. The key is humic substances in organic soils.

Researchers at Northwestern University in Illinois developed a new process to measure humic acids, making this research possible. Over a nine-year period, the scientists analysed 659 organic soil samples and 728 conventional soil samples across from over 1,000 farmers in almost every U.S. state. They found that the organic soils held substantially higher levels of humic acids than conventional samples.

Dr. Tracy Misiewicz, co-author and Associate Director of Science Programs for The Organic Center, is presenting information related to this discovery in a series of free webinars. In the first one, she set the context for the recent research by highlighting that food system emissions are responsible for up to one third of greenhouse gas emissions, and that agricultural production produces 80-86% of these emissions. Next, she pointed to research showing the advanced ability of organic management to reduce these numbers.

Organic crop production for corn, soy, and wheat would consume 60% less energy on average (including 25% fewer global warming emissions) than conventional production according to a 2008 study by Pelletier et al. Organic systems also hold more total soil organic carbon on average than conventional systems, even compared to low- and no-till conventional practices, when measured to a depth of 1m from the surface (Cavigelli et al, 2013).

The key to the value of the recent study is that not all carbon held in the soil is equal. The two main pools of carbon in the soil are either labile, which has a high turnover, or a stable pool – also known as humic substances – which have a low turnover. Humic substances include humic and fluvic acids, and are linked with higher soil fertility and beneficial soil structure. Most studies focus on total soil carbon, which is a less reliable number over time. The results showed that, on average, organic soil samples held 13% higher organic matter, 44% more humic acid, and 1.5 times more fulvic acid.

This study confirms that although organic agriculture is not carbon-neutral, it can lead the way in reducing emissions and storing stable forms of carbon from the atmosphere. This is timely information, published just one month before OMAFRA’s recent Draft Soil Health and Conservation Strategy, motivated by province’s Climate Change Action Plan.

Dr. Misiewicz is already curious about next steps for research based on the findings: which practices are most effective at building stable pools of carbon? How can the increases in carbon sequestration be translated into emissions offsets? How can organic systems further reduce greenhouse gas emissions such as methane and nitrous oxide? And how can this research be translated into tools for farmers and the industry?

The three remaining free webinars will take place at the following times: Wednesday November 29^th 1-2pm, Tuesday December 5^th 12-1pm, and Monday December 11^th, 1-2pm (all Eastern Standard Time).

Register by clicking here, or visiting: https://register.gotowebinar.com/rt/9120286610771117059

Sources:

Cavigelli, M.A., S.B. Mirsky, J.R. Teasdale, J.T. Spargo, and J. Doran. (2013). Organic grain cropping systems to enhance ecosystem services. Renewable agriculture and food systems, 28, 145-159.

Ghabbour, E.A., Davies, G., Misiewicz, T., Alami, R.A., Askounis, E.M., Cuozzo, N.P., Filice, A.J., Haskell, J.M., Moy, A.K., Roach, A.C., Shade, J. (2017). Chapter One – National Comparison of the Total and Sequestered Organic Matter Contents of Conventional and Organic Farm Soils, Editor(s): Donald L. Sparks, In Advances in Agronomy. Academic Press, 146, 1-35. Accessed from: https://doi.org/10.1016/bs.agron.2017.07.003

Misiewicz, Tracy. (2017). How does organic mitigate climate change? [power point]. The Organic Centre.

Nicodemo, Allie. (Oct 4, 2017). Study Finds Organic Soil Captures, Holds More Carbon. The Organic Centre. Accessed from: https://www.organic-center.org/study-finds-organic-soil-captures-holds-more-carbon/

Pelletier, N., Arsenault, N. & Tyedmers, P. (2008). Scenario modeling potential eco-efficiency gains from a transition to organic agriculture: life cycle perspectives on Canadian canola, corn, soy, and wheat production. Environmental Management, 42, 989.