Adapted from Dan Bensonhoff’s article in the NOFA July 2016 Newsletter
Doing less damage is no longer good enough when it comes to addressing cascading challenges like climate change, habitat loss and soil loss. To address these issues, many ecological farming practitioners have been touting the idea of “regenerative agriculture.” But what does it really mean? It stands in clear juxtaposition to the more widely used term, sustainable agriculture. There’s no question that the land and water we are now working with has been massively degraded through decades of unscrupulous industrial practices, ignorance of basic ecological principles, and human folly.
Specifically, in New England, we have inherited numerous overgrazed pastures, polluted rivers, and de-mineralized hay fields. So, as North Dakota farmer Gabe Brown asks: “Why would we want to sustain a degraded land and soil?” and the answer is, we don’t. We want to restore it. But how?
Roughly 6,000 years ago the indigenous peoples of the Amazon basin developed a technique that allowed them to sustain intensive agriculture on soils generally considered to be extremely nutrient-poor. By applying biochar made from excess vegetation in an oxygen-less burn, they were able to continuously plant crops on the same land year after year, whereas those that weren’t using biochar generally had to allow land to lie fallow for a decade or more before it was considered ready for agriculture again.
Since the discovery of this Amazonian “Terra Prata” (literally, “dark earth”), research on biochar has found that when biochar is carefully made and integrated into farm systems, the resulting farm system can actually be carbon-positive, meaning that the system captures more carbon that it emits (on a farm, carbon is emitted through tillage, motorized equipment, plastics, etc.). Biochar is reported to have a half-life ranging from decades to millennia, depending on the feedstock used to make it, meaning that once it’s in your soil it will stay in a stable form much longer than other plant material.
Even more impressive, biochar can be made using cheap agricultural or forestry by-products. These materials, which include wood chips, nut shells, manure, bones, and much more, would otherwise be burned or left to oxidize, thus adding carbon to the atmosphere. Through pyrolysis (oxygen-less burning), those by-products become much harder for soil microorganisms to break down, hence why they have a longer half-life.
The pyrolysis process also imbues a spongy, porous structure to the biochar. Those pores then become ideal habitat for bacteria, fungi, and nematodes, which in turn mineralize (make available) the nutrients that crops feed on. Other major advantages that biochar offers farmers and gardeners include…
enhanced water retention
moderation of soil acidity
increased cation exchange capacity
less leaching of nitrogen and other water-soluble nutrients
Biochar is not the only way we can restore soils, we can also restore soil by planting cover crops, or, where you have ground cover, increasing the diversity of grasses you plant. By seeding diversified stands of cover crops or ground cover, your soil will reap benefits that a monoculture stands of rye, fescue, or oats cannot achieve. This technique, often known as cocktail cover cropping, combines the services of a number of different types of cover crops simultaneously. By mixing together grasses, legumes, and other broadleaf plants, the cover crop will produce more overall biomass and nitrogen, tolerate adverse conditions, increase winter survival, provide ground cover, improve weed control, attract a wider range of beneficial insects and pollinators, and provide more options for use as forage. Essentially, this technique mimics natural grasslands, which are never composed of one plant family, much less one or two species.