Maturity selection but not sowing date enhances soybean productivity and land use in a winter camelina-soybean relay system

Authors: Mohammed, Yesuf; Gesch, Russell - Russ; MATTHEES, HEATHER - Winfield United; WELLS, SAMANTHA - University Of Minnesota

Submitted to: Food and Energy Security
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/3/2021
Publication Date: 2/1/2022
Citation: Mohammed, Y.A., Gesch, R.W., Matthees, H.L., Wells, S.S. 2022. Maturity selection but not sowing date enhances soybean productivity and land use in a winter camelina-soybean relay system. Food and Energy Security. 11(1). Article e346. https://doi.org/10.1002/fes3.346.
DOI: https://doi.org/10.1002/fes3.346

Interpretive Summary: In the upper Midwest USA, after harvesting spring wheat, the land is usually left fallow until the next spring exposing the soil for erosion and nutrient losses. An oilseed crop called winter camelina can be planted following spring wheat harvest thus providing live cover to the soil while at the same time allowing soybean to be grown the following spring. Winter camelina can be harvested mid to end of June above the soybean canopy. This practice of growing two or more crops at the same time on the same field is called relay cropping. Relay cropping can add more crops such as winter camelina to the cropping systems thus increasing plant diversity on the farm. Diversified cropping systems have the potential to stabilize incomes, increase soil health and provide other ecosystem services. However, previous relay systems showed soybean yield tradeoff due to the relay practice compared with monocrop soybean. To minimize this yield gap, we evaluated three soybean relative maturity groups at three different soybean seeding dates in standing winter camelina. The results showed that relaying soybean at first flowering of camelina decreased camelina seed yield compared with monocrop camelina. This was likely caused by wheel traffic damage to camelina. Soybean grain yield gap between monocrop soybean and relayed soybean was less than 10% when late maturing soybean variety was used. Soybean relayed around winter camelina bolting growth stage produced 39% greater total (camelina + soybean) oil yield than the corresponding monocrop soybean and increased land-use efficiency. Further research is warranted to optimize soybean variety choice for relaying soybean with winter camelina for different geographical regions. This information will benefit producers interested in relaying soybean in winter camelina, extension specialists and consultants in advising producers in crop diversification and intensification. The information will also benefit other scientists interested in developing improved relay cropping practices to increase winter camelina and soybean production.

Technical Abstract: Relay-cropping soybean [Glycine max (L.) Merrill] in winter camelina [Camelina sativa (L.) Crantz] can help to diversity and intensify crop production in the Upper Midwest US. However, soybean yields in relay systems tend to be lower than full-season monocrop. Improving soybean selection and seeding date for relaying into camelina could help to minimize this yield gap. The objectives of this study were to determine the effects of soybean relative maturity group (MG) and seeding dates (SD) on winter camelina and soybean seed yields and quality, and land use productivity in a winter camelina-soybean relay system. Three soybean relative MGs (MG0.2, MG1.1 and MG1.7) were relayed into winter camelina at rosette (SD1), bolting (SD2) and first flowering (SD3) growth stages of winter camelina and were compared with monocrop soybean and winter camelina. The results showed that relaying soybean at first flowering of camelina significantly decreased camelina seed yield compared with monocrop camelina. This was likely caused by wheel traffic damage to camelina. Soybean grain yield gap between monocrop and relayed systems was minimum (<10%) when late maturing soybean variety was used. Soybean MG1.7 relayed at SD2 produced 39% greater total (camelina + soybean) oil yield than the corresponding monocrop soybean. The soybean MG1.7 at SD2 showed the best combination for increased total seed and oil yields, and land use productivity. Further research is warranted to optimize soybean variety choice for relaying soybean with winter camelina for the different geographical regions.