Winter wheat is the main crop in the Pacific Northwest and growers normally seed around 2.2 million acres every fall. Yet year after year, an average of anywhere from 1.3 to 22.3 tons of silt loam soil erodes from every acre that is in wheat production.
“Sometimes the roads around our lab are covered with eroded soils that are a foot deep,” says Dan Long. The research leader at the Columbia Plateau Conservation Research Center in Pendleton, Ore., says most area growers still rely mainly on conventional tillage for growing wheat despite the terrible soil losses.
Until Agricultural Research Service hydrologist John Williams initiated a watershed-scale study on tillage practices, there was no real data available on how different tillage practices could reduce area soil erosion. Plus, the researchers wanted to determine if no-till might help reduce soil losses.
“No-till production for wheat has been studied in the Midwest and the Southeast, but we have different issues in the Pacific Northwest,” Williams says. “We have multiple freeze-thaw events every year and our farmers are growing wheat on 20- to 45-degree slopes.”
The scientists evaluated water runoff, soil erosion and wheat yields in an intensively tilled wheat-and-fallow system with a 4-year no-till program. Plots were seeded in two neighboring drainage areas within the Wildhorse Creek Watershed in northeast Oregon.
The scientists discovered there was 70% more runoff and 52 times more eroded material that escaped from the conventionally tilled fields than with no-tilled wheat.
“In this case study, there were no significant difference in yields between the two systems,” Long adds. “From a cost-benefit perspective, direct-seeding minimizes the trips across a field that a farmer needs to make, which saves fuel and time in the long run.”
The researchers also learned that the no-till soils that had eroded down the steep slopes moved much more slowly over time than those in conventional fields. This was in contrast to more sudden and severe erosion typical with heavy rainfall storms in the area.
No-till also improved the levels of soil organic carbon, which increased soil aggregation and led to increased soil stability.
“I expected to see big differences in erosion rates between no-till and conventional till, but the magnitude surprised me,” says ARS soil scientist Hero Gollany. “But I didn’t realize how much soil was going down the hills from conventionally tilled fields.”
The researchers believe this data will go a long way in helping eastern Oregon wheat growers balance their immediate economic returns with the need for sustainable crop management. For the first time, area growers can actually see the significant environmental differences between no-till and conventional tillage — and it’s an excellent story to share.