Intercropping in maize silage verses solo-seeding for alfalfa establishment in Wisconsin and Idaho

Authors: Grabber, John; Bjorneberg, David - Dave; Rogers, Christopher

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/24/2023
Publication Date: 2/10/2024
Citation: Grabber, J.H., Bjorneberg, D.L., Rogers, C.W. 2024. Intercropping in maize silage verses solo-seeding for alfalfa establishment in Wisconsin and Idaho. Crop Science. https://doi.org/10.1002/csc2.21189.
DOI: https://doi.org/10.1002/csc2.21189

Interpretive Summary: Alfalfa intercropping with a corn silage companion crop is being developed in colder regions of the USA to improve the profitability and environmental sustainability of forage production. The purpose of this study was to compare the establishment and initial yield of alfalfa interseeded into corn to conventional methods for alfalfa establishment. The study was carried out in Wisconsin and Idaho, which are among the leading states for forage and dairy production in the USA. During the establishment year, we found that the corn silage companion crop for interseeded alfalfa produced 1.8- to 4.4-fold more forage than conventionally spring-seeded alfalfa. The following spring, the forage yield of interseeded alfalfa was comparable to conventional spring seeded alfalfa and often superior to conventional summer seeded alfalfa. Overall interseeding gave good establishment of alfalfa and yields of forage that were greater than alfalfa established by conventional methods. Our results will help to promote adoption of alfalfa-corn intercropping by dairy and forage producers in the northern USA.

Technical Abstract: Alfalfa (Medicago sativa L.) intercropping with corn (Zea mays L.) silage is being developed in colder regions of the USA to improve the profitability and environmental sustainability of forage production. This two-year study carried out under relatively dry conditions in Wisconsin and semiarid irrigated conditions in Idaho compared alfalfa establishment and initial forage yields of three solo-seeding methods for alfalfa (spring-seeded, summer-seeded after barley (Hordeum vulgare L.), or late summer/early fall-seeded after corn silage) to four alfalfa-corn intercropping methods. Alfalfa was interseeded at corn planting or at corn VE stage and grown with or without prohexadione. Interseeded and spring seeded alfalfa were treated with fungicide and insecticide in Wisconsin but not in Idaho. During the alfalfa establishment year, yields of intercropped corn silage were 1.8- to 4.4-fold greater than spring-seeded alfalfa. Compared to spring seeded alfalfa, interseeded alfalfa had similar or somewhat lower stand density but similar first cut yield the following year, provided that intercropped corn was harvested near September 1st to allow ample fall regrowth of alfalfa before winter. Shifting alfalfa interseeding from corn planting to the corn VE stage decreased early season alfalfa growth, but improved corn silage yields, with only minor effects on alfalfa fall growth, stand density, and first cut yield. Prohexadione application had little impact on interseeded alfalfa establishment or yield. While having high fall plant density, alfalfa seeded after barley or especially corn had less fall growth and relatively low first cut yield. Overall, intercropping compared favorably with solo-seeding methods for alfalfa establishment.