Yet tillage is needed as a step for controlling weeds on most organic farms because of prohibition of synthetic herbicides, which are used for “no-till” agriculture in conventional farming. The Rodale Institute’s white paper recognizes the problem of “marginal” practices of no-till or reduced-tillage on organic farms. For these reasons, the organization has been working on a
roller-crimper technique intended to squash cover crops or weeds as a method of organic “no-till” agriculture. But the fact is that the technology is unlikely to be available as a large-scale approach anytime soon.
The scientific research evaluating “reduced-tillage” organic farming hasn’t been promising either. One
study by soil scientist Jane Johnson and her colleagues from the USDA-Agriculture Research Service evaluated reduced-tillage farming in both the organic and conventional methods during a four-year rotation of corn, wheat, soybean, and alfalfa in Minnesota. The researchers used closed-vented chambers to monitor greenhouse gas emissions for three years during early spring thaws until late fall.
During those four years, they found that yields varied, but averaged much lower for organic farming. In 2007 and 2008, for example, organic and conventional yields for soybean were found to be similar, but 2006 organic soybean was 90 percent lower than conventional yields. Organic and conventional corn yields were similar for 2007, but then organic was 60 percent lower than conventional in 2006, and 40 percent lower during 2008. In 2006, organic wheat also was 50 percent lower than conventional wheat yields.
The researchers also found that while both conventional and reduced-tillage organic systems emit nitrous oxide emissions, the amount cumulatively represented 4.74 percent of nitrogen of the synthetic nitrogen added into the conventional system compared to 9.26 percent of the nitrogen from manure added to the organic system. Essentially, the organic farming system had nearly twice the nitrous oxide emissions for the same amount of nitrogen applied compared to the conventional system—for a smaller yield!
More land use means more cows and methane gas
Still the smaller yields requiring more acres of land for tillage doesn’t yet highlight what would likely be the single greatest threat on the environment were more conventional farmers to turn to organic farming—it’s the need for all the extra cattle to produce manure to fertilize those organic crops. The extra cattle would not just take up additional land; they’d lead to huge releases in greenhouse gas emissions resulting from manure production itself and from burping and farting. One
estimate is that every individual cow lets out between 30 and fifty gallons of methane per day, from both its behind and mouth.
Currently, cattle livestock is already blamed for generating
nearly 20 percentmore greenhouse gases in terms of carbon equivalency as compared to driving automobiles. The problem could grow far worse as
summarizedquite succinctly by Ramez Naam, author of
Infinite Resource: The Power of Ideas on a Finite Planet:
