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Farm Scale Study: Summary of 2010 Results

July 19, 2011

Last year was a bad year for our Energy Farm yields. The summer began with flooding and ended with drought.

Rainfall recorded at the experiment site between May and November, 2010, relative to long term average rainfall for the county.

Our yields — at all farm scales — were the lowest yet.

Mean yield of food and energy crops grown at three farming scales between 2008 and 2010. Biointensive plots are managed with hand tools only. Market garden plots are managed using walk-behind tractors and smaller tools. Small farm plots are managed using all available equipment, including conventional four-wheeled tractors. Organic practices are used at all scales.

Although planting was delayed by flooding, the plots looked pretty good by mid July.

High school intern Lisa Liu surveys a market garden scale plot on July 13, 2010.

By October, when Google’s satellites snapped an overhead view of the farm, everything was brown and crispy. The sweet sorghum stood out as the only green in the plots. The combination of drought and hungry deer hit the soybeans hard, and devastated the sweet potato.

Energy farms study (inset) on the Kentucky State University Research and Demonstration Farm (shaded green). Google image, October 2010.

As in previous years, we invested far more time in the Biointensive plots, which are managed entirely with hand tools, than in equivalent areas of plots managed with some machinery. Biointensive plot preparation took longer in 2008 than in subsequent years because “double digging” was conducted in the first year only. In 2009 and 2010 we loosened the double dug beds with a U-bar.

Labor used for preparation, planting, maintenance, and harvest at three small farm production scales between 2008 and 2010.

All of the energy invested in the Biointensive plots was metabolic energy, but most of the energy invested at the other farm scales came from fossil fuels, in the form of gasoline and diesel. The energy investment did not differ dramatically between farming scales or years.

Metabolic and fossil energy invested in farming at three scales between 2008 and 2010.

Energy efficiency was about the same at all scales in 2010. Over the three years of the study so far, only 2009 has demonstrated any energy advantage to human-powered farming. This has surprised me.

Energy efficiency at three farming scales between 2008 and 2010.

It comes as no surprise that the smallest-scale systems have offered a lower return to human labor than those that use more machinery.

Labor efficiency at three farming scales between 2008 and 2010.

We’re now well into our fourth year of the study. So far, the weather has been more cooperative than in 2010 and the soybeans and sweet potatoes are doing much better. For some reason, our corn and sweet sorghum germination has been poor, though. This year our Biointensive plots, where everything was transplanted, look much better than our Small Farm and Market Garden plots, where all but the sweet potatoes were direct seeded.

Direct seeding Market Garden and Small Farm plots, June 2011 (video, top). Biointensive (lower left) and Small Farm plots (lower right), July 14, 2011.

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