A recent "Agronomy Journal" article reports on a study that has important information for Pacific Northwest growers of oilseed crops. In the study, camelina and safflower produced in three-rotations with winter wheat and summer fallow call for special tasks.
Using this rotation may require that no tillage should be done to the soil during the fallow year, says the USDA-Agricultural Research Service/Washington State University research reported in the journal. The probe focused on blowing dust emissions from oilseed fields. The Columbia Plateau experiences significant windblown dust form excessively-tilled ag lands.
Oilseed crops produce relatively little residue such as roots that hold the soil together, and even light tillage can disintegrate the soil, report researchers William Schillinger of WSU and Brenton Sharratt with the ARS.
They found that adding camelina or safflower crops into a rotation with winter wheat and summer fallow increased the amount of dust at the end of tillage-based fallow or when wheat is planted.
"Farmers will need to protect the soil from wind erosion during the fallow phase after harvest of the oilseed crops," says Sharratt.
Parts of the Pacific Northwest are low precipitation regions, and the typical crop rotation is a winter wheat-summer fallow process, with one crop grown every second year. The fallow period allows the soil to store winter moisture from rain and snow, which is stored into the soil for the critical seed germination process after planting occurs, and to provide emerging wheat water.
The researchers measured dust particles, or wind erosion, using a portable wind tunnel 24 feet long with a fan used to generate conditions like those occurring naturally in the fields.
The scientists found that adding camelina or safflower into the crop rotation increased the chances of wind erosion late in the fallow cycle.
Their advice to farmers is to use techniques to preserve the soil. Even the Undercutter experimented with by Schillinger at the WSU Dryland Research Station near Ritzville, of which he is superintendent, "is too much tillage for fallow after oilseeds in the dry region," he says.
"No-till fallow, or planting another crop without a fallow year, is the answer for controlling blowing dust."