Water use in camelina-soybean dual cropping systems

Authors: Gesch, Russell - Russ; Johnson, Jane

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/2015
Publication Date: 5/5/2015
Publication URL: http://handle.nal.usda.gov/10113/60946
Citation: Gesch, R.W., Johnson, J.M. 2015. Water use in camelina-soybean dual cropping systems. Agronomy Journal. 107(3):1098-1104.

Interpretive Summary: Double-cropping is the practice of planting a second crop after harvesting the first crop, which in most cases is a winter annual crop. Relay-cropping is the practice of seeding a second crop into the first crop (a winter annual crop) before it has matured, so that their lifecycles overlap. These farming practices are used often in the southern U.S. to produce winter wheat and soybean in the same season. However, this is not practiced in the upper Midwest because the growing season is too short. ARS researchers in Morris, Minnesota, are the first to show that soybean, as a food crop, can be double- and relay-cropped with winter camelina, as a biofuel crop, as far north as western Minnesota to successfully produce both a food and fuel crop in a single season on the same parcel of land. The primary reason for this is that camelina has a very short lifecycle and can survive Minnesota winters. However, one of the most limiting factors to double- and relay-cropping is having enough water during the growing season to successfully produce both crops. We devised a field experiment to measure the seasonal water use of winter camelina and soybean used in both double and relay crop systems and compared this to a full-season soybean crop that would typically be grown in Minnesota. We discovered that in most years, there is enough water stored in the soil and replenished by rain throughout the summer in western Minnesota to successfully grow both winter camelina and soybean in same season on the same piece of land. This "new" cropping system will allow farmers to sustainably fit a bioenergy crop into their crop rotations to produce a biofuel crop (i.e., camelina) along with a food crop such as soybean in a single season. Besides adding diversity to agricultural landscapes, the importance of this is that it allows a biofuel crop to be grown on highly productive lands without sacrificing food security. Obviously, this research has the potential to directly benefit farmers, but will also benefit the biofuel industry. The results will also help extension personal and crop consultants determine the best areas to implement camelina-soybean dual cropping based on its water use requirements.

Technical Abstract: Dual cropping systems can be potentially used as a sustainably intensified approach to integrating the production of food, feed, fiber, and fuel (i.e., bioenergy) on agriculturally productive landscapes. Recently, we reported that winter camelina (Camelina sativa) can be feasibly double- and relay-cropped with soybean [Glycine max (L.) Merr.] in the northern Corn Belt region. However, water availability can be a limiting factor for dual crop systems. In the present study, we determined seasonal water use in various winter camelina-soybean dual crop systems that included two sequential double-crop and two relay-crop treatments compared to a full-season monocropped soybean. The rooting characteristics of camelina were also evaluated. The study was conducted on a Barnes loam soil in west central Minnesota over two growing seasons in 2010 and 2011. Camelina was found to have a meager root system with 82% of its root density found in the top 0.3 m of soil. Although both double- and relay-crop treatments used more seasonal water than a sole soybean crop, on average it was only 26 and 50 mm greater in 2010 and 2011, respectively. Camelina is a low water user compared to soybean. Total cropping system water use efficiency for relay-cropping was comparable to the sole soybean crop, but for the double-crop treatments it was less. Not only is this cropping strategy a way to integrate food and fuel production on productive lands, but additionally, our results indicate that it may be amenable to most dryland-farming areas in the upper Midwest where soybean is grown.