Environmental trade-offs of relay-cropping winter cover crops with soybean in a maize-soybean cropping system

Winter camelina [ Camelina sativa (L.) Crantz] and field pennycress Thlaspi arvense L.] are oilseed feedstocks that can be employed as winter-hardy cover crops in the current cropping systems U.S. upper Midwest. In addition to provide multiple ecosystem services, they a further source of income for farmer. However, using these is new agricultural practice has only been studied recently. The objective this study was assess compare environmental performance maize Zea mays L.]-soybean Glycine max Merr.] system with different winter - camelina, pennycress, rye ( Secale cereale L.) Field experiments were carried out from 2016 2017 (2-year maize-soybean sequence) at three locations: Morris (Minnesota), Ames (Iowa), Prosper (North Dakota). impact assessment “cradle-to-gate” life cycle methodology. Four categories assessed: global warming potential (GWP), eutrophication, soil erosion, organic carbon (SOC) variation. Two functional units (FU) selected: (1) 1 ha year ?1 , (2) $1 net margin. When expressed FU yr across locations had (a) lower eutrophication water (b) GWP if crop not fertilized nitrogen. more effective than reducing losses, while provided similar results potential. SOC variation mixed, but sequence best all locations. $ margin, sequences including overall worst mitigating greenhouse gas emissions nutrient losses. This negative mainly due seed yield reduction second both main cash (soybean) relayed-cover compared conventional maize-soybean. Such result led margin per hectare when control. suggest introduction strong impacts rotation. management optimization relay-cropping needed make them sustainable practice. • rotation without assessed. Three annual interseeded into standing autumn followed by soybean following spring. reduced emissions, erosion hectare. Economic sustainability challenge crops.