With one of the Midwest’s longest-running studies of tillage methods and fertility coming to an end, Southern Illinois University researchers at Carbondale, Ill., can tell farmers three things for sure:

1. Yields will not, in the long run, drop if farmers plant their crops without plowing.
2. Even if farmers just spread fertilizer on top of the soil, plants will get more than enough nutrients. Farmers don’t have to mix nutrients into the soil to get the benefits.
3. The best thing that no-tillers can do to boost yields is to rotate crops.

More than 30 years in the making, the findings are a little anticlimactic, admits agronomist Edward C. Varsa who, with former weed scientist George Kapusta, oversaw most of the research. Varsa estimates that U.S. farmers no-till nearly 25 percent of their corn and over 55 percent of soybeans.

Plenty of Progress

But when these studies first began, no one knew much about this reduced-tillage practice. “No-till had just gotten out of the research stage and into the field,” Varsa recalls. “There was no information dealing with long-term effects. That’s why George’s contacts in the industry wanted him to do this study.”

Kapusta set up four groups of continuous corn plots:

• Used the moldboard plow to turn everything under.
• Used a chisel plow to rip through the soil.
• Wasn’t plowed or tilled at all.
• Tillage systems were alternated with the last group of plots, no-tilling for 2 years and then plowing for 1 year.

“Within the first 5 to 10 years…