Why we grow foods organically

Ice on the pond. Credit Ezra Freeman

Ice on the pond.
Credit Ezra Freeman

Hoophouse greens in November. Credit Ethan Hirsh

Hoophouse greens in November.
Credit Ethan Hirsh

Here we have a second day of cold grey drizzle. The day length is as short as it gets. I have little enthusiasm for working outdoors. But this is a good time of year to remind myself why I value growing good food in a sustainable way. I want people to live healthy happy lives, and I want us to leave a planet worth inheriting.

I’ve just been reading Can organic crops compete with industrial agriculture? by Sarah Yang from Media Relations at UC Berkeley. There is a common belief that while organic farming is better in terms of doing less damage to the environment than chemical agriculture, it cannot ever feed the world. Sarah Yang says “A systematic overview of more than 100 studies comparing organic and conventional farming finds that the crop yields of organic agriculture are higher than previously thought.” And the productivity gap could be shrunk from 19.2% to an 8-9% difference in direct yield by sustainable organic farmers adopting or improving on certain practices.

The full study, entitled Diversification practices reduce organic to conventional yield gap, by , Claire Kremen was published on 12/10/14 in the Proceedings of the Royal Society. Global food needs will likely increase enormously in the next 50 years, and even if we were prepared to accept hugely increased environmental degradation from chemical farming, the fact remains that chemical fertilizers cannot increase yields by much above current levels.

The researchers did a meta-analysis of 115 studies (three times more than any previously published study) comparing organic and currently-conventional agriculture in 38 countries and 52 crops over a period of 35 years. Yields from organic farms are on average 19.2% lower, although this may be an over-estimate. The various studies incorporated here show a very wide range. In some developing countries with few resources, adopting good sustainability practices increased yields 180% over the previous systems in place.

I doubt the recorded yields take into account the land lost by erosion, or that used for mining minerals for fertilizers or growing corn for bio-diesel for the extensive farm machinery used in currently-conventional farming.

Shifting away from environmentally damaging agriculture would be a good step. Increasing the land farmed organically from the current 0.9% and “Broad adoption of sustainable agricultural methods is unlikely, however, unless such methods are similarly productive and/or cost-effective, such that they improve livelihoods.”

How can organic farmers increase yields? The report suggests big yield improvements can come from giving more attention to crop rotations and multi-cropping (growing several crops together on the same field), two basic tenets of organic farming. (We can always aim to do these things better!) Other suggestions include increasing ecological diversity and harnessing ecological interactions by intercropping or cover-cropping with legumes to gain their nitrogen-fixing benefits.

More investment in research into organic management systems and breeding varieties (especially of cereals) suited to organic growing could (can!) reduce or in some cases eliminate the gap. Organic farming has been historically underfunded compared to agriculture which uses lots of products from Agribusiness, and crop varieties designed to work well with those synthetic inputs.

The senior author of the study, Claire Kremen, makes these important points: “It’s important to remember that our current agricultural system produces far more food than is needed to provide for everyone on the planet. Eradicating world hunger requires increasing the access to food, not simply the production. Also, increasing the proportion of agriculture that uses sustainable, organic methods of farming is not a choice, it’s a necessity. We simply can’t continue to produce food far into the future without taking care of our soils, water and biodiversity.”


Another interesting piece of recent farming news is the 12/2/14 report by Ken Olson from ACES Cover crops can sequester soil organic carbon. This 12 year study at the University of Illinois showed that cover crops do not increase crop yields, but do increase the amount of sequestered carbon in the soil. This benefit accrues in no-till, chisel-plowed and moldboard plow methods. the no-till system including cover crops, sequestered the most carbon. Ken Olson said that soil organic carbon losses caused by tillage, water erosion, soil disturbance, aeration, nitrogen injection and mineralization were less than  soil organic carbon gained from cover-crops.

The complete study Long-Term Effects of Cover Crops on Crop Yields, Soil Organic Carbon Stocks and Sequestration can be read here.

A cover crop mix of winter rye, hairy vetch and crimson clover. Credit Kathryn Simmons

A cover crop mix of winter rye, hairy vetch and crimson clover.
Credit Kathryn Simmons