Tillage Trials

Summer 2018

By Ben Hoffman

Minimal tillage is essential for healthy, productive soils. In a seven-year study at the University of Western Australia, total organic carbon in the top 4 inches of soil increased by 1.7 tons/acre with no-till and 1 ton under conservation tillage but decreased by 0.2 tons under rotary tillage. (“Tillage, microbial biomass and soil biological fertility,” by Margaret Roper et al., University of Western Australia.)

Based on that and other diatribes on rotary tillage, I contemplated selling my rototiller. After flail mowing yellow clover and Warthog wheat and watching the surface litter decompose in the sun, I set the tiller for medium depth and tried to incorporate the plant material into the soil. Then, after reading “Advancing Biological Farming” by Gary Zimmer and Leilani Zimmer-Durand, I reset the tiller for deeper tillage; you can’t incorporate green manure without tillage, and the green manure should be green. Try to minimize soil disturbance in the rooting zone, leaving as much of the previous crop roots intact, for microorganism chow, and you’ll help the health of your soil.

I modified a 12-row, three-point hitch grain drill to sow nine rows at 8-inch spacing, using S-tines and sweeps ahead of each coulter/seed drop to cut vegetation in the grain row below the root collar to kill it. This works in Dutch white clover (DWC), but with surface trash the sweeps simply collect, drag and clog with trash. Practicing no-till when surface trash is present requires cutting through the trash with discs. Replacing four of the nine sweeps with discs helped, but incorporating surface litter with rotary tillage before drilling solves the problem. If you must use no-till and if you are a business member of the Maine Grain Alliance, you can borrow its nice Kasco drill, which can be used as a no-till drill, by contacting [email protected].
When sowing Banatka wheat or Eco barley at 8- by 8-inch spacing, how do you deal with weeds? I broadcast DWC after seeding and it formed a 3- to 5-inch-tall understory that occupied the entire area, and few weeds grew. Dutch white clover, a tenacious, low-growing species, fills the space between plants. It is not the most productive clover for biomass or nitrogen production, but it does a great job of controlling weeds and is not tall enough to get into my mini-combine. Plus, after harvesting grain, the cover crop is in place.

Eero Ruuttila, research station manager for Johnny’s Selected Seeds, uses medium red clover for weed control, but I have not tried it. In Banatka wheat, which reaches 5 feet in height, I tried red clover, but it grew to 4 feet, clung to the wheat tillers and pulled them down, and combining was impossible. My neighbor tried taller white clover varieties and found that they grew taller but not dense enough to shade weeds. Yellow sweet clover, which I planted to break up a plow pan and then did not kill successfully, grew as tall as the wheat and made combining impossible.

To minimize tillage, I have used white clover as a living mulch with wheat, barley and oats, followed by dry beans and potatoes. See my article “The Farmall Cub” in the winter 2017-2018 issue of The Maine Organic Farmer & Gardener.

Another option for strip tilling is to remove some tines from a tractor tiller and till two rows at a time. On small plots, doing one strip at a time with half of the tines removed from a walk-behind rototiller might work.

I hope you can benefit from my learning the hard way.

About the author: Ben Hoffman is a retired forester and who cultivates a few acres in Bradford, Maine.

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