Microbial Farming Would Mobilize the ‘Intricate Ecosystems’ Beneath Our Feet
Microbial farming, which involves reseeding exhausted farmland with the diverse microbiome upon which productive soil depends, 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.
In a thimble-sized amount of healthy soil, writes Drawdown, “there can be up to 10 billion denizens, and between 50,000 and 83, 000 different species of bacteria and fungi.” The precise constituents of any two such thimbles sampled “within just a few feet” of each other will “depend on whether the soil is under sorghum, an oak tree, or a molehill.”
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While much about the intricate ecosystems alive beneath our feet remains mysterious, Drawdown explains, growing clearer is the recognition that harnessing the natural powers of the microbiome could significantly reduce agricultural greenhouse gas emissions, now estimated at 30% of annual global totals.
Exhibit A, writes Drawdown, is the ongoing quest to discover a nitrogen-fixing bacteria that will work its magic for wheat, as other strains of bacteria are well-known to do for legumes. For now, in the absence of such a discovery, 1.2% of the world’s total energy is devoted to converting nitrogen into ammonia-based fertilizers, with most of the nitrogen ultimately ending up in the atmosphere as nitrous oxide, “a greenhouse gas 298 times more powerful than carbon dioxide over the course of a century.” Alternately, “it leaches into groundwater and waterways, causing the overgrowth of algae and dead zones where marine life suffocates from lack of oxygen.”
Having been alerted to the existence of the microbiome, reports Drawdown, “every big agricultural company in the world,” is “researching, partnering with, and gobbling up start-ups in the field of soil microbe identification and testing.” But Big Ag errs, Drawdown warns, in its default assumption that microbes are to be enlisted as “weapons” against everything from worms to weeds. The approach ignores the benefits of the symbiosis that seems the rule of a soil kingdom left to its own devices.
For example, “a healthy soil biome is rich in carbon because soil microbes feed on sugar-rich exudates from the roots of plants,” while in return, “the bacteria dissolve rock and minerals and make those nutrient bioavailable to plants,” Drawdown notes. The chapter concludes that the future of agriculture lies in “doing what life does,” at least at the soil level, where co-evolution and webs of mutual support and give-and-take sustain a “virtuous cycle” of life and death—not the selective “weaponizing” of one life form in order to eradicate another.