A recent study published in Agronomy Journal provides information important to farmers growing oilseed crops. In the study, camelina and safflower were grown in three-year rotations with winter wheat and summer fallow. The study shows that using this rotation may require that no tillage should be done to the soil during the fallow year. Oilseed crops produce relatively little residue--organic material such as roots that hold the soil together. Even light tillage can disintegrate the soil.
A cooperative study by the USDA-ARS and Washington State University researched the effects of growing oilseed crops--camelina and safflower--on blowing dust emissions. The Columbia Plateau of the Inland Pacific Northwest experiences significant windblown dust from excessively-tilled agricultural lands.
Brenton Sharratt and William Schillinger 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 oilseed crops," says Sharratt.
The Pacific Northwest is a low-precipitation region. The typical crop rotation there is winter wheat-summer fallow. Thus, one crop is usually grown every other year. The fallow period allows the soil to store moisture from rains and snows over the winter. This stored moisture is critical for seed germination and emergence of winter wheat.
The researchers measured dust particles, or wind erosion, using a portable wind tunnel. This tunnel was 24 ft long, 4 ft tall and 3 ft wide. A fan was used to generate conditions like those naturally occurring in the fields. Their findings show that adding camelina or safflower into the crop rotation increased the chances of wind erosion late in the fallow cycle. Thus, their caution to farmers is to use techniques to preserve the soil. "Even the undercutter method is too much tillage for fallow after oilseeds in the dry region," say the researchers. "No-till fallow, or planting another crop without a fallow year, is the answer for controlling blowing dust. "
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