Monday, May 12, 2008

No-Till Farming?

John McCain gave a big speech on global warming and energy policy today. Here's an AP article if you missed it:

Joseph Romm, one of the climate/energy policy bloggers I read on the subject, had this critique:

"McCain’s cost-containment strategy for his climate policy is a fraud. It substitutes a huge amount of low cost, phony emissions reductions both here and abroad — called offsets — for actual domestic emissions reductions."

One of the offsets that McCain touts is something called "no-till farming." I have to admit, I don't know a lot about no-till farming, yet, but rest assured the subject will be at the top of the agenda during coffee break tomorrow morning.

In the interim, I consulted my trusted advisor, Wikipedia. She tells me right away that no-till farming was once called "chemical farming," which doesn't sound especially wholesome:

"Some farmers [use] a 'burn-down' herbicide such as Glyphosate in lieu of tillage for seedbed preparation, and because of this, no-till is often associated with increased chemical use in comparison to traditional tillage based methods of crop production."

Glyphosate, if you're not familiar with it, is the generic name for Roundup, manufactured by argibusiness giant Monsanto. Roundup has come up in conversation on the farm at least a few times. Farmer Jeremy used to work at a job in which he had to spray the stuff. He says that when it first came out, everyone told him it was safe and non-toxic, no worries. But a few years later, that changed – a few studies found that apparently it's not-so non-toxic. (A quick Googling reveals that the safety of Roundup is still very much up for debate.)

Anyhow, I also have no idea whether no-till farming reduces carbon emmisions. But here is the abstract of an article in Agriculture, Ecosystems and Environment, which Romm cites in his post:

It is widely believed that soil disturbance by tillage was a primary cause of the historical loss of soil organic carbon (SOC) in North America, and that substantial SOC sequestration can be accomplished by changing from conventional plowing to less intensive methods known as conservation tillage. This is based on experiments where changes in carbon storage have been estimated through soil sampling of tillage trials. However, sampling protocol may have biased the results. In essentially all cases where conservation tillage was found to sequester C, soils were only sampled to a depth of 30 cm or less, even though crop roots often extend much deeper. In the few studies where sampling extended deeper than 30 cm, conservation tillage has shown no consistent accrual of SOC, instead showing a difference in the distribution of SOC, with higher concentrations near the surface in conservation tillage and higher concentrations in deeper layers under conventional tillage. These contrasting results may be due to tillage-induced differences in thermal and physical conditions that affect root growth and distribution. Long-term, continuous gas exchange measurements have also been unable to detect C gain due to reduced tillage. Though there are other good reasons to use conservation tillage, evidence that it promotes C sequestration is not compelling.