Tuesday, March 16, 2010

No-Till vs. Organic Soil Management

I just came across a cool USDA study on the impacts of various minimum tillage cultivation schemes on grain yields in the Mid-Atlantic. They compared a range of minimal-till farming systems from conventional to organic with different combinations of cover crops, living mulches and different levels of herbicide and nitrogen input.
"After nine years, corn yields were similar in the standard no-tillage and cover crop systems but were 12% lower in the crownvetch system and 28% lower in the organic farming system than in the standard no-tillage system."
The shockingly poor yield of organic grain here was due to a massive proliferation of weeds - which are extremely difficult to control without herbicide.
They also measured yield of corn that was grown conventionally on fields that had been in either conventional or organic production for the previous 9 years. Conventionally-grown corn yields were 18% higher when grown on fields that were historically managed organically.
Organic management (in this system) really improved the soil - mostly through increased nitrogen levels, probably. The catch though is that the organic fields were overwhelmed with weeds!

Sounds like a good opportunity to combine the best of both approaches.

2 comments:

  1. "Sounds like a good opportunity to combine the best of both approaches. "

    I like the way you think. Too many people think it's got to be one way or the other.

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  2. I think people get sucked into those kinds of dualisms because they're really confident about some subset of their knowledge or values, and when they see the "opposite" group lining up their own views, they naturally assume they're against everything the other group is for. Political parties is a really obvious example.

    I find it easier to be open minded by constantly reminding myself how little I really know. Good scientists really nurture this perspective. I once heard an anecdote about a professor who was a world expert in some group of beetles. A lay person asked his lab to identify one they found. His grad students went through all their knowledge and notes and confidently pronounced the identification, but when the professor himself was asked, he said there were far too many species (many unknown) and they were too similar to identify the bug in question. The professor knew enough to know what he didn't know.

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