As increased levels of dissolved phosphorus are identified as a major concern dealing with the increased algal blooms found in Lake Erie, some folks have been pointing a finger at no-till as the cause. Yet the facts regarding phosphorus runoff in the Western Lake Erie Basin watershed near Toledo, Ohio, don’t back up that argument.
“Sure, there is a lot of no-till planting in the watershed,” says Steve Davis, the National Resources Conservation Service (NRSC) watershed specialist at Lima, Ohio. “But the percentage of long-term continuous no-till is still small in this area.”
This watershed includes 4.9 million acres in northwest Ohio, northeast Indiana and southeast Michigan. In any given year, about 40% of the watershed has no form of conservation tillage or protective residue cover on the soil surface at planting time.
Davis cites data from a recently completed 5-year study of the watershed to refute the claims against no-till.
While phosphorus can run off no-till fields, especially if it rains right after application, Davis says the same is true when phosphorus is applied to conventional- and minimum-tilled fields. He maintains several factors working together are more likely to explain the increase in levels of dissolved phosphorus runoff in Lake Erie:
- Changes in the methods and timing of fertilizer applications.
- Use of broadcast surface application vs. row-applied fertilizer.
- Applying fertilizer during the winter on frozen ground.
- Increased soil compaction concerns due to larger equipment.
- A growing trend toward applying 2 years worth of fertilizer at one time on a single corn crop.
The water-monitoring data indicates the level of dissolved phosphorus has increased in runoff. Yet, particulate phosphorus and sediment in the runoff has definitely declined due to increased use of no-till. “We certainly need to drastically reduce dissolved phosphorus runoff,” he says. “But no-till is an important tool in a farmer’s conservation toolbox.
“I don’t see farmers going back to the days of fencerow-to-fencerow moldboard plowing and all its problems. Fuel prices won’t allow that, the costs of cleaning drainage ditches and dredging harbors won’t allow that, nor will a public that values clean water.”
During the 5-year period (2006 to 2010), only 6.9% of the corn was no-tilled, 32.1% of the soybeans were no-tilled and 9.9% of the wheat was no-tilled. Nearly 70% of the corn acres are still grown without any form of conservation tillage.
If tillage was distributed uniformly throughout the watershed over a 10-year period, each field would be no-tilled every other year, conventionally tilled in 4 of the years and mulch-tilled once.
So there’s still plenty of opportunity for growers to expand their no-till acres in an effort to better control phosphorus levels in Lake Erie. When this happens, everyone wins.