Preliminary data: Energy and labor use in KSU energy farm study through July
Scientific inquiry would be pointless if it didn’t occassionally turn up unexpected results. I had certain expectations when I designed the farm scale study we are currently conducting at Kentucky State University:
- Our ‘biointensive’ plots — managed entirely with hand tools — would be labor intensive but energy efficient;
- Our ‘small farm’ plots — managed with a combination of tractors and other machinery commonly used on conventional farms in North America — would be energy intensive but labor efficient;
- Our ‘market garden’ plots — managed with a combination of hand tools and small, fuel-driven machines — would combine the best of both worlds, being more energy efficient than the ‘small farm’ system, and more labor efficient than the ‘biointensive’ system.
That’s not how things turned out this July.
Before I introduce the latest data, let me report some general observations.
The farm looks beautiful right now. I have posted field maps before, but you might get a better idea of what the site looks like from the picture above, which my research assistant, Brian Geier, took this afternoon. Look down past the grazing goats, past the aquaculture pond, and you can see almost the entire three acres dedicated to our energy farm study. Beyond it are verdant hillsides, typical of Kentucky’s Bluegrass region.
Down in the plots you get a better idea of the different farm scales. This is my undergraduate student research assistant, John Rodgers, working in one of the ‘Biointensive’ plots. A ‘Small Farm’ plot is off to the left, and a ‘Market Garden’ plot is in the distance.
Here’s a similar view from inside a ‘market garden’ plot. From left to right, the crops in both of the photos above happen to be sweet sorghum, soybean, sweet potato, and corn (this is just a coincidence; crop position was randomized). Notice how much bigger the sweet sorghum is in the ‘market garden,’ relative to the ‘biointensive’ plot. We had better establishment of crops planted with the Earthway seeder than those that were hand-seeded. That was a surprise; we thought we were babying the hand-seeded plants. Next year we might try transplanting corn and sorghum into the ‘biointensive’ plots to give them a head start.
Here is the sweet potato planting in a ‘small farm’ plot. Sweet sorghum in on the left, with corn on the right. Both the sweet sorghum and corn are much further advanced in the ‘small farm’ plots than in the other plots because they did not have to be re-seeded. The initial pass with the moldboard plow in the ‘small farm’ plots required a tremendous amount of energy, and may not have been good for the soil structure, but it did a great job of burying weed seeds that were near the soil surface. Weeds choked out the young corn and sorghum seedlings from the first planting in the ‘biointensive’ and ‘market garden’ plots, but not in the ‘small farm’ plots.
The graphs above show the most recent data on cumulative labor and energy use at each of the farm scales from May through the end of July. I have divided each bar into three segments: Black shows labor and energy invested in preparing the soil for planting, purple shows labor and energy invested in planting, and yellow shows labor and energy invested in managing the plots after planting. Only the yellow (management) segments have changed since I posted preliminary data at the end of June.
Those yellow segments surprised me. Contrary to my expectation, the ‘market garden’ plots have required almost as much management time per square meter as the ‘biointensive’ plots, and much more energy per square meter than the ‘small farm’ plots. From a post-planting management perspective, the ‘market garden’ scale looks like it combines the worst of both worlds instead of the best.
Remember that these are preliminary data, and the story may well change as we continue this study through the rest of this season and into the coming years. That’s what makes it interesting.
Michael Bomford provides research and extension services related to organic agriculture and small-scale renewable energy production through Kentucky State University’s Land Grant Program.
He thanks Tony Silvernail, Brian Geier and John Rodgers
for their help with maintaining the organic land at the KSU Research Farm. Special thanks go to Joelle Johnson, who completes her 6-week internship, much of it spent at the business end of a hoe, tomorrow. All photos in this post were taken by Brian Geier and John Rodgers today, July 31, 2008.