To recap P. 1, building healthy soil in the garden means taking care of the billions of living organisms underfoot. It’s not as big of a job as it sounds. In our small community garden plots, we can adjust our practices easily and work less by retiring old methods like double-digging and other strenuous soil churning. Easing up on soil disruption protects its complex ecosystem and makes for happier plants.
Soil for the Planet
If that’s not enough to convince you to put down the shovel, consider the climate. One of the key drivers of climate change is the burning of fossil fuels, but did you know that some modern agricultural practices–including tilling–also have released significant amounts of carbon into the atmosphere?
Where is that carbon coming from? It’s right there in the soil, everywhere. It’s in the roots of plants, in decaying leaf mulch, in earthworms, in sugars released by plants, and in long threads of fungal networks. Around 50% to 58% of the organic matter in soil is carbon.
Unfortunately, our cultivated land has lost around half of its organic matter, from 5% levels of soil organic matter down to less than 3%. We want that carbon back! Soil life is built from carbon and depends on it to survive, which makes soil a great reservoir for carbon. In the soil it can do good things for us, whereas too much of it in the atmosphere contributes to climate change.
Regenerative agriculture or carbon farming aims to do just that–to put carbon back into the soil using a variety of practices, including no-till farming. It’s not a straightforward process. Some of the systems at work in the garden naturally put carbon back into the atmosphere no matter how carefully we tend our soil. For example, all of those wonderful soil microbes expire carbon dioxide when they break down organic material. Microbes in an acre of corn can expire as much carbon dioxide as twenty five active men.
In very rough terms, it’s a two-step-forward/one-step-back kind of a process, which means that the goal of carbon farming is to put more carbon into the soil than is released. Here’s where things get a little tricky and controversial, figuring out the best agricultural practices to sink the most carbon and keep it in the soil. Soil scientists have paid attention to a substance called glomalin, produced by fungi, which acts like a glue holding soil particles together in aggregates. (Remember, that cottage-cheesy, pebbled texture?) Some scientists think glomalin may tie up 27% of soil carbon for as long as 40 years.
Soil scientists have also paid attention to humus, the carbon-rich, coffee-colored, fertile part of soil. It’s hard to define humus exactly because it’s not clear how humus is formed; some think it’s a product of decomposition of organic matter, while others think that it’s a built-up product of soil organisms utilizing the sugars exuded by plants. In any case, the important quality of humus is that like glomalin, it’s considered by many to be recalcitrant, meaning that it’s likely to stay in the soil for a long time. These are the kinds of long-term storage we need to draw down the imbalance of carbon in the atmosphere.
Farmers worldwide are already using regenerative agricultural practices, in no small part because they improve productivity and in the long-run, make economical sense. Green America is cheering on home gardeners to do the same. Their idea is this: our individual plots may be small, but collectively, we might be able to make a difference, similar to the way victory gardeners of WWI and WWII grew up to 40% of the fresh produce consumed in the U.S..
The posters above were published by the U.S. Food Administration, created by Woodrow Wilson by executive order in 1917. Leading the newly-formed administration, Herbert Hoover had the power to act as “food dictator,” but strove to design “an effort that would appeal to the American sense of volunteerism and avoid coercion.” (I know I’m getting a little off track here, but I think this is interesting stuff and definitely relevant to the question of how to get large groups of people to act quickly in helpful ways for a common cause–like climate change.)
Ditching some of our old gardening methods may not only build the soil for our plants, but also may make a positive impact on the planet. I’m convinced at the very least that strategies that support soil life yield more productive, sustainable, and healthier gardens. As we’ve said before at PPCG, our only organic gardening rule that we enforce is “no synthetic agricultural chemicals.” But I hope you’ll consider making some changes in how you tend your plot, if for no other reason than you’ll get better results. For more info, take a look at the links below.
Up next, since I know we’re all itching to get in the garden: regenerative techniques we can use in our own gardens.
For More Info…
Another accessible piece–on fungi and their role in the carbon cycle–from NPR.
From Northeast Farming Association (NOFA), really helpful white paper on soil carbon restoration. Read this if you want to go into more depth on this topic. It’s written for the general public and covers a lot of ground. NOFAMass has become my favorite go-to source on soil-building.
From the New York Times Magazine, an article on changing agricultural practices to draw down carbon from the atmosphere. (Local readers: if you don’t have a NYT subscription and have used up your free monthly articles, our local library offers free three-day passes. Here’s a link to digital media.)
The Soil Will Save Us by Kristin Ohlson (2014). I haven’t been able to get a copy of this book yet, but it looks like it’s available through Boston Public Library.
From nature.com, a relatively short, but more technical presentation of soil carbon sequestration. This was the first piece I read that helped me understand the balance of carbon inputs and outputs. Also covers some aspects of carbon sequestration such as soil mineralogy and land topography.
SOS: Save Our Soils. Very interesting 2015 interview with Dr. Christine Jones, soil ecologist. Some of this material was not fully explained for the general reader, but it covers a broad range of topics.
Want more posters? (I love this stuff!) Google ‘victory garden posters’ and ‘women’s land army.’