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"Michigan State University-led research has found a big difference in the yields produced by alternative agricultural practices in commercial fields compared with the same practices in the small experimental plots ordinarily used to test them. These differences have important implications for closing the global yield gap between research plots and farmer fields, especially for low-input practices adopted by organic farmers in the United States and by resource-strapped farmers in less developed regions. The study, published in the latest issue of PNAS, compared the yields of a crop rotation of wheat, corn and soybeans under three different management practices: conventional, low-input and organic. The tests were conducted at small experimental plots and the much larger commercial field level. Though researchers found no appreciable difference in the yields produced at either level for conventional crop management, they noted a significant yield gap for both low-input and organic management. According to Sasha Kravchenko, lead author and MSU plant biologist, this difference can be attributed to the additional challenges that large-scale production presents to both low-input and organic practices. Conventional management relies on the uniform application of chemical inputs such as fertilizer and pesticides, practices that can easily be scaled up to larger fields. In contrast, low-input and organic management require much more labor-intensive work, as well as the cultivation of cover crops, which is more difficult to perform consistently on large tracts of land. Because of the difficulty of scaling up low-input and organic practices to commercial fields, those farmers may see as much as a 30 percent lower yield than research suggests. “The big conclusion is that, when you have management practices that require a lot of time and effort, and when the success of the practice requires more work than a farmer could reasonably do in an entire farm, then we as scientists need to adjust our recommendations,” said Kravchenko, who’s also an MSU AgBioResearch scientist. “Our study shows that if you don’t invest in field-scale studies, you run the risk of recommending impractical methods that won’t produce the promised level of return.”"

Posted January 18th, 2017