Location: Soil Management Research
Title: Dual cropping winter camelina with soybean in the northern Corn Belt Authors
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 12, 2014
Publication Date: N/A
Interpretive Summary: Because of the federal government’s push to increase the amount of renewable energy produced in the U.S., farmers are under even more and more pressure these days to produce biofuel crops in addition to food and fiber crops. This gives farmers new economic opportunities, which is good, but it also increases pressure on agricultural lands to produce additional crop biomass for biofuel production. This in-turn jeopardizes the long-term sustainability of our farmlands and the environment in general. Because of this, new cropping systems are needed that can produce both food and fuel economically while being good stewards of the land. One way to perhaps do this is through producing two crops, one a biofuel crop and the other a food crop all in the same growing season, which is referred to as “double-cropping.” In the upper Midwest, this means using a winter cover crop (as the first crop), which farmers and scientists already know is a good idea, followed by a short-season summer crop like soybean. Our previous research has shown that this is possible using winter camelina as a cover crop (for biofuel) and then following it with a short maturity group soybean as the summer crop (food crop). However, much more work is needed to refine this cropping system and determine its economic value. Therefore, a multi-year field study was conducted in west central Minnesota to test different methods of double-cropping, also referred to as dual cropping, and determine economic returns and energy outputs of different dual cropping methods to produce winter camelina and soybean in the same growing season on the same piece of land. Our results showed that camelina yields were consistent across years regardless of the dual cropping method used producing about 1200 lbs/acre of seed, whose oil can be used for making biofuel. Of the dual cropping methods tested, relay-cropping, which is inter-seeding soybean between rows of camelina early in the spring, worked the best for producing the highest soybean yields (40 bushels/acre) as compared to a conventional (i.e., single season crop) soybean crop. Relay-cropping also gave the highest economic returns and energy outputs for the dual cropping methods tested. It was also found to be economically competitive with producing a conventional single-season soybean crop. This research will likely benefit the biofuel and specialty seed industries, and provide useful information to extension personal, farmers and crop consultants seeking to grow a “cash” cover crop and establish a dual crop system that produces a biofuel and food crop in a single season.
Technical Abstract: Sustainably balancing biofuel crop production with food, feed, and fiber on agricultural lands will require developing new cropping strategies. Double- and/or relay-cropping winter camelina (Camelina sativa L.) with soybean [Glycine max (L.) Merr.] may be a means to produce an energy and food crop on the same land in a single year. A study was conducted between 2009 and 2011 in west central Minnesota to evaluate yields, seed quality, economics, and within field energy balance of winter camelina-soybean double- and relay-cropping systems compared to a conventional mono-cropped full-season soybean. Systems included methods to hasten camelina harvest (e.g., swathing and desiccating) to promote early soybean growth. Camelina seed yields were unaffected by cropping system and ranged from 1.1 to 1.3 Mg ha-1. Relay-cropped soybean yields were greater than double-cropped soybean and were 58 to 83% of that for the mono-cropped control. Seed oil and protein content of double- and relay-cropped soybean were comparable to, and combined seed oil yield for the dual crop systems was as much as 50% greater than, the mono-cropped soybean. Net economic returns for the relay-crop system were competitive with that of the full-season soybean. Moreover, energy outputs of the relay-crop system were as high as or higher than a sole soybean crop, but energy efficiency was less for the dual cropping systems due to greater inputs. Results indicate that dual cropping of winter camelina with soybean is agronomically viable for the upper Midwest and might be an attractive system to growers seeking a “cash” cover crop.