Desiccation of corn allows earlier direct seeding of winter camelina in the northern Corn Belt

Authors: Gesch, Russell - Russ; WELLS, M - University Of Minnesota; HARD, ALEX - University Of Minnesota

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/24/2021
Publication Date: 4/28/2021
Citation: Gesch, R.W., Wells, M.S., Hard, A. 2021. Desiccation of corn allows earlier direct seeding of winter camelina in the northern Corn Belt. Crop Science. 61(4):2787-2797. https://doi.org/10.1002/csc2.20549.
DOI: https://doi.org/10.1002/csc2.20549

Interpretive Summary: Because corn is often harvested late in the fall in the Upper Midwest, there is typically not enough time to effectively plant cover crops before the soil freezes. Winter camelina is a winter hardy cover crop with great potential to help diversify the traditional corn-soybean rotation in the Corn Belt. However, the extent of its impact as a cover may depend on how well it can be established after corn harvest. A study was conducted to use a safe preharvest chemical desiccant (sodium chlorate) sprayed on corn to speed up its drying in the field so that it could be harvested earlier than normal. We hypothesized that doing this would allow direct no-till planting of camelina early enough to promote good fall establishment leading to better spring biomass production and seed yield. We found that applying desiccant too early to corn caused a significant decrease in grain yield of 16%. However, desiccating corn about a week earlier than black layer (i.e., physiological maturity) did not affect yield but did speed up dry-down in the field allowing corn to be harvested about one to two weeks early. This allowed enough time for camelina to be planted in the fall to achieve good stand establishment and improve its seed yield. Nevertheless, more work may be needed to improve management and the genetics of camelina for its use as a cover crop following corn. This information will benefit scientists, farmers, seed companies, educators, and ag consultants working on incorporating cover crops into corn-soybean cropping systems.

Technical Abstract: In the Upper Midwest US where growing seasons are short, establishing winter annual cover crops following corn (Zea mays L.) is challenging. Winter camelina [Camelina sativa (L.) Crantz] shows promise as a winter annual cover crop that can be dual cropped with soybean [Glycine max (L.) Merr.] to help diversify the corn-soybean rotation. This two-year field study in southern and western Minnesota evaluated desiccating corn with a pre-harvest aid to hasten its dry-down and hence harvest so that camelina could be no-till drilled in a timely manner. We hypothesized that direct-drilling camelina following corn harvest would improve establishment and yields. Sodium chlorate as a desiccant was applied to corn at early (D1) and mid-R5 (D2) and physiological maturity (D3) stages of development, including an untreated check. The D1 and D2 treatments hastened corn harvest by 1 to 3 weeks compared with the check. Corn grain yields were unaffected by the D2 and D3 treatments, but significantly declined by 16% in D1. Camelina establishment was greater in western Minnesota where seed yields were as high as 1163 kg ha-1. However, camelina seed yield did not differ among desiccation treatments and averaged 815 kg ha-1 across both locations with an average oil content of 385 g ka-1. Desiccating corn hastened its harvest allowing more time to drill seed camelina, thus improving establishment. However, more work is needed to improve management and genetics of winter camelina for use as a cover in corn systems.