Camelina and Moisture

In these times of severe drought in many places in our country, wouldn't it be nice if soils could retain enough rainwater for multiple crops in one growing season. Russ Gesch, a plant physiologist with the USDA Soil Conservation Research Lab in Morris, Minnesota and his colleagues measured water use of two systems of dual-cropping using camelina and soybean. They compared it with a more typical soybean field at the Swan Lake Research Farm near Morris, MN.

First, researchers planted camelina at the end of September. From there growing methods differed. In double-cropping, soybean enters the field after the camelina harvest in June or July. Relay-cropping, however, overlaps the crops' time. Soybeans grow between rows of camelina in April or May before the camelina plants mature and flower.

The benefits were numerous. Relay-cropping actually used less water than double-cropping the two plants. Camelina plants have shallow roots and a short growing season, which means they don't use much water. Conveniently, the extra water use during dual-cropping takes place in the spring when we tend to have an excess of moisture in the soil due to melting snow pack. So Gesch says growing camelina as a winter cover crop can help farmers take advantage of spring's extra moisture. Oh, one other thing. Aside from the moisture issue there is a nutritional benefit. The oil of camelina has even more vitamin E than soybeans.

Gesch points out the need for more water use does mean camelina dual-cropping may not be the best option in all areas. "As you get further west and precipitation drops off and soils get lighter with lower water-holding capacity, crop yields may start to go down," says Gesch.

Growing camelina as a winter cover crop can also have other benefits, according to Gesch. "We had greater soybean yields with the relay-cropping system than when double cropping," says Gesch, referencing a previous study. The earlier planting date during relay cropping allows for a longer growing season and contributes to the higher yield, according to Gesch.

In addition, camelina plants flower early in the spring, providing a vital food source for pollinators, like bees, when little else is available to them. As a cover crop, camelina may also help prevent erosion and build soil carbon content. Gesch and his colleagues are working to measure these ecological benefits of dual-cropping.