Replacing soil-depleting annual food species with perennial crops is one of the 20 carbon reduction options that Drawdown lists as Coming Attractions—strategies that weren’t ready for prime time when the book was published, but looked like promising approaches through mid-century.
Whereas annuals die back completely each year, and must be replanted—typically at great cost to soil health—perennials regenerate from their roots, and are thus “the most effective way to sequester carbon in any agricultural system because they leave the soil intact,” writes Drawdown.
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The global quest to successfully breed high-yield strains of perennial food crops from wild ancestors is accelerating, with crucial advances being made at the Yunnan Academy of Agricultural Sciences in China. Researchers there are focusing on breeding perennial rice from “four wild ancestors that spread through roots or above ground stems (much like strawberries) and yield crops for several years.” Because the crafted rice, like its wild cousins, could grow on unirrigated upland fields (rather than lowland rice paddies), hopes are high that the new perennial rice will “minimize deforestation by farmers who cultivate rice only for a few years and then move on, using slash-and-burn techniques because of lack of fertility.”
Also hard at work are plant geneticists at the Land Institute in Salina, Kansas who are well into a 40-year effort to breed perennial wheat. “They may have it in a variety called Kernza,” say Drawdown authors.
Kin to a wheatgrass species native to Western Asia and Europe, Kernza is truly a breed apart from conventional wheat: “Whereas annual wheat has a spindly three-foot root, Kernza’s roots are thick and robust and go down 10 feet” where they exchange plant carbon with bacteria “that in turn acidify rocks and stones into mineral nutrients for the wheat.”
Drawdown calls that “a good deal for the plants and soil, with no tilling required.”
While Kernza is not yet in wide distribution, and other efforts to produced perennial food crops have been troubled by small kernel size and low yields, research efforts are intensifying around the globe, and show great promise.