Photo: Jim Robinson, USDA-NRCS/CC BY 2.0, Flickr

Farming Carbon into Soils and Trees: A Climate-Smart Mid-Century Strategy for Agriculture

, senior scientist | November 14, 2016, 3:16 pm EST
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In 2050, the Paris Agreement will be 34 years old,  Google will be 52,  the National Park Service will be 134, the tractor will be 158, the United States will be 274, and hopefully we’ll all be celebrating being well along the way to a cooler future. While it may seem like a lot of time, there’s a lot of work ahead of us.

That’s why leaders around the world have been working in the aftermath of the Paris Agreement to develop strategies to reduce net global warming emissions to established goals by mid-century (2050). As it turns out, an important part of this work has to do with boosting food, farms, and farmers—and that’s what I’ll talk about. However, if you’d like to learn about other solutions, check out the posts by my colleagues on biofuels, forests, and the energy sector.

First, a note about the land carbon “sink”

There is growing awareness of the value of the so-called “land carbon sink”. What is this all about?  Well, plants and soils store carbon, keeping it out of the atmosphere. The more carbon can be “sequestered” into leaves, roots, stems tree trunks, and soils each year, the bigger the carbon “sink” and the smaller the climate change problem. Currently, about 762 million Mt CO2e worth of carbon are stored in plants and soils in the US. This is significant—enough to offset 11% of emissions— but insufficient given the magnitude of the climate change problem. Not only that, but since storing more carbon in lands also means building and protecting healthier soils, an investment in soil health simply makes sense. Luckily, the USDA already has a plan to help farms and forests sequester or offset an extra 120 million Mt CO2e/y (by 2025). This plan is a step in the right direction, but we can do better.

A role for agriculture in a cooler future

Although the burden of mitigating climate change can’t be all on agriculture’s plate, the sector has a lot to contribute and a lot to gain from efforts to solve climate change. Here are some key points to consider:

  1. There is room for more carbon farming: USDA’s NRCS already supports practices that enhance soil carbon on millions of acres each year, but these programs could be improved and expanded to enable a soil sink of over 270 million Mt CO2e by 2050.
  1. On croplands, there are many ways to increase carbon: Research reveals that several agricultural practices can build soil carbon, including no-till, cover cropping, crop rotations, perennials, and residue management. There is some uncertainty regarding the potential of each practice, but growing evidence suggests a role for all.
  1. Grazing systems matter: A large proportion of agricultural lands are grazed grasslands, which can store a lot of carbon. Management of these lands affects both carbon sinks and greenhouse gas emissions, and more research is needed to learn how to maximize carbon gains while reducing grazer emissions.
  1. More trees on farms can help: Planting trees on farms, “agroforestry”, can also be good for climate (carbon is stored in soils and trees), farmers, water, wildlife, and more. There are many strategies that could help, from planting trees in borders around fields to integrating them into crop and grazing systems (“silvopasture”).
  1. Innovative solutions are on the horizon: Several other tools currently being researched could also contribute to the solution. For example, perennial grains (such as Kernza) and soil amendments (like biochar, compost).
  1. Carbon farming has co-benefits: Farming that increases soil carbon can bring additional benefits. For example, cover crops can produce nitrogen and agroforestry can prevent nitrogen loss, reducing fertilizer needs and lowering nitrous oxide emissions. A big picture perspective is needed to identify best practices.
  1. It’s time to boost soil carbon science: Soil carbon sequestration varies, is hard to measure, changes over time, and can be reversed. Obtaining a better understanding of how much carbon can realistically be sequestered in agricultural soils, and for how long, is more urgent than ever.
  1. Food security is part of the puzzle: Land use changes must be considered alongside food security needs, especially in light of existing food insecurity and projected increases in population. These issues emphasize the importance of plant breeding efforts and yield-boosting practices such as diversified farming.
  1. Supporting farmers is key: Farmers who choose to adopt new practices will need plenty of support, to ensure both long-lasting climate benefits and vibrant, productive farms.

We (only) have 2.3 billion acres

Let’s face it. There’s only so much land, so expanding any “land use” (use of land for forests, food, fuel, or houses) means that something else has to give.  With that in mind, it’s becoming ever more important to develop farms that meet multiple objectives. The possibility of multi-functional landscapes is extremely promising, but there’s a lot left to learn – just another reason why more public funding for agroecological research is so urgently needed.

What will the US look like mid-century? It’s up to all of us

The land around us needs changing and, while there is still a lot to learn, promising directions are beginning to emerge. Fortunately, these include win-win opportunities in food and agriculture. For example, by working to increase soil health and soil health science, increase agricultural resiliency, incentivize and support farms, and reduce waste, food and agriculture can be a big slice of the solution.

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