ENVIRONMENTAL SUSTAINABILITY OF DOUBLE AND RELAY CROPPING OF FOOD, FEED, AND FUEL CROPS IN THE NORTHERN GREAT PLAINS, USA

摘要

Recent findings indicate that that double- or relay-cropping of winter camelina (Camelina sativa L. Crantz.)rnwith biomass or food crops is an alternative to increase yield per area while providing several ecosystem services. Thernobjective was to determine the environmental impact of double and relay-cropping systems in comparison with the mostrncommon crop monocultures in the Midwest, maize (Zea mays L.) and soybean (Glycine max (L.) Merr.). Ten crop sequencesrncomposed of double- and relay-cropping of biomass sorghum [Sorghum bicolor (L.) Moench.], soybean, and maize,rnfollowing winter camelina were evaluated and compared with monocultures of same crops. The life cycle analysis (LCA) wasrnconducted from ‘cradle-to-gate’, including only the agricultural phase. Global warming potential (GWP), estimated by threerndifferent methods, indicated that winter camelina had a GWP of 579 to 922 kg CO_(2e) ha~(-1). Adding a second crop after winterrncamelina, in relay or double cropping, increased GWP on 235 to 540 kg CO_(2e) ha~(-1). Maize in monoculture had higher GWPrnthan all other cropping systems studied. Camelina had the lowest values in all environmental impact categories, indicatingrncamelina agricultural production phase has low impact in the environment. Double- and relay- cropping systems increasedrnbiodiversity and decreased soil erosion potential. More research indicating the benefits of double and relay systems to thernenvironment are needed to get more farmers to adopt sustainable agricultural practices.