Meta Study of Organic Farms

The LA times reports on a study in Nature which looked at studies of organic agriculture, finding an average 20 percent difference in productivity.  The impact varies by crop, with annuals more affected than perennials and fruits.  

One commenter spins:

In fact, in cases in which growers used techniques that are considered to be the best practices for organic farming, the gap between organic and conventional yields narrowed to 13%.
"If you do things as well as you can, then the yield difference is very small," Cavigelli said.

There's no indication of whether the non-organic farms were using their "best practices", but my cynical self suspects they weren't.  There's also no indication of whether the comparison was crop to crop, or acre to acre (the latter meaning the total productivity of an acre over several years).