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

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2021-01-01
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Cecchin, Andrea
Pourhashem, Ghasideh
Gesch, Russ
Mohammed, Yesuf
Patel, Swetabh
Berti, Marisol
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Lenssen, Andrew
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Agronomy

The Department of Agronomy seeks to teach the study of the farm-field, its crops, and its science and management. It originally consisted of three sub-departments to do this: Soils, Farm-Crops, and Agricultural Engineering (which became its own department in 1907). Today, the department teaches crop sciences and breeding, soil sciences, meteorology, agroecology, and biotechnology.

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The Department of Agronomy was formed in 1902. From 1917 to 1935 it was known as the Department of Farm Crops and Soils.

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1902–present

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  • Department of Farm Crops and Soils (1917–1935)

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Abstract

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 in the U.S. upper Midwest. In addition to provide multiple ecosystem services, they can be a further source of income for the farmer. However, using these cover crops is a new agricultural practice that has only been studied recently. The objective of this study was to assess and compare the environmental performance of a maize [Zea mays L.]-soybean [Glycine max (L.) Merr.] cropping system with different winter cover crops - camelina, pennycress, and rye (Secale cereale L.) - in the U.S. upper Midwest. Field experiments were carried out from 2016 to 2017 (2-year maize-soybean sequence) at three locations: Morris (Minnesota), Ames (Iowa), and Prosper (North Dakota). The environmental impact assessment was carried out using a “cradle-to-gate” life cycle assessment methodology. Four impact categories were assessed: global warming potential (GWP), eutrophication, soil erosion, and soil organic carbon (SOC) variation. Two functional units (FU) were selected: (1) 1 ha year−1, and (2) $1 net margin. When expressed with the FU ha yr−1, across the three locations cover crops had (a) lower eutrophication potential and water soil erosion, and (b) lower GWP if the cover crop was not fertilized with nitrogen. Camelina and pennycress were more effective than rye in reducing soil losses, while the three cover crops provided similar results for eutrophication potential. The results for the SOC variation were mixed, but the sequence with rye had the best performance at all locations. When expressed with the FU $ net margin, sequences including camelina and pennycress were overall the worst sequences in mitigating greenhouse gas emissions and nutrient and soil losses. This negative performance was mainly due to the seed yield reduction in the second year of the sequence for both the main cash crop (soybean) and the relayed-cover crop compared with the conventional sequence maize-soybean. Such result led to a lower net margin per hectare in the sequences including camelina and pennycress when compared with the control. The results of this study suggest that the introduction of camelina and pennycress as winter-hardy cover crops has a strong potential for reducing the environmental impacts of the maize-soybean rotation. However, a field management optimization of these cover crops in a relay-cropping system is needed to make them a sustainable agricultural practice.

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This article is published as Cecchin, Andrea, Ghasideh Pourhashem, Russ W. Gesch, Andrew W. Lenssen, Yesuf A. Mohammed, Swetabh Patel, and Marisol T. Berti. "Environmental trade-offs of relay-cropping winter cover crops with soybean in a maize-soybean cropping system." Agricultural Systems 189 (2021): 103062. doi: 10.1016/j.agsy.2021.103062.

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