These Iowa Learning Farm side-by-side replicated demonstration strips comparing no-till planting with row cleaners to fall inline subsoil tillage on Collin Jensen’s West Union, IA, farm reveal little economic benefit to subsoiling. In 2008, for example, the Iowa Learning Farms replicated demonstration showed subsoiling reduced Jensen’s per-acre returns by $77.19/acre, or 13%, and consumed 75% more fuel (relative to the no-till planted treatments).

Jensen’s Fayette County, IA, corn-soybean rotation plots are predominantly Port Byron soils. They’d been in continuous no-till from the early 1980s until these multi-year trials began in 2006.

Northeast Iowa ISU Extension Agronomist Brian Lang says, “If he didn’t have much compaction to start with (because of long-time reduced tillage), that would explain why there was little or no yield benefit to the fall subsoiling. However, sometimes in a cold spring the fall subsoiling pass moves some residue and creates a warm-up band. And if that’s your goal, then use fall strip-till. It’s less expensive than a subsoil pass,” Lang says. “That provides a warm, open zone the next spring relative to a no-till pass with row cleaner.”

Jensen adds, “Most years the no-till and the fall subsoiled plots looked alike through the growing season. There were some differences in the final stands, but there was not enough revenue difference to justify the cost, especially when I included the risk of spring soil erosion.” (Iowa had record rainfalls during these years, concentrated into large events.) The 2008 subsoiled plots had about seven times the soil loss as the no-till ones, the data shows.