Alfalfa establishment by interseeding with silage corn projected to increase profitability of corn silage-alfalfa rotations

Authors: Osterholz, William - Will; RENZ, MARK - University Of Wisconsin; Grabber, John

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/20/2020
Publication Date: 5/27/2020
Citation: Osterholz, W.R., Renz, M.J., Grabber, J.H. 2020. Alfalfa establishment by interseeding with silage corn projected to increase profitability of corn silage-alfalfa rotations. Agronomy Journal. 112(5):4120-4132. https://doi.org/10.1002/agj2.20312.
DOI: https://doi.org/10.1002/agj2.20312

Interpretive Summary: In temperate regions like the Midwest US, rotations between alfalfa and corn harvested for silage are the primary source of forage for dairy production. While the rotations have important animal health, productivity, and environmental benefits, a weakness is the low productivity of alfalfa in the year it is first seeded, or the establishment year. Planting alfalfa in the same field and at the same time as a corn silage crop, a practice know as interseeding, allows farmers to harvest corn silage while alfalfa is establishing and thus can enhance overall forage productivity. However, interseeding also incurs additional costs, as corn yield can be adversely affected and alfalfa establishment by this method occasionally fails due to competition from the corn crop. Therefore the overall economic effect of the practice remains uncertain, so in this study we conducted an economic analysis of the interseeding system. We simulated the economics of corn silage-alfalfa rotations of various lengths used detailed estimates of production costs and revenue from the 2012-2017 period. Results show that rotations utilizing interseeding increased profits by $7-36 per acre (7-36%) compared to the conventional rotations. Gains in profitability were ensured when alfalfa establishment was successful more than half of the time, or when the corn yield loss due to interseeding was less than 20%. Additional analyses showed that an application of plant protective chemicals to interseeded alfalfa would enhance profitability if it generated a greater than 16% increase in alfalfa establishment success. Interseeding alfalfa into corn silage is an economically beneficial practice that could enhance profitability of corn silage-alfalfa based cropping systems in temperate regions under recent economic conditions.

Technical Abstract: Corn (Zea mays L.) silage and alfalfa (Medicago sativa L.) rotations dominate dairy forage production in temperate regions, but low forage production during conventional establishment of spring seeded alfalfa limits overall system productivity and profitability. Interseeding alfalfa into corn silage is a novel establishment method that could enhance alfalfa forage production and farm income, but it also incurs additional costs. In this study, crop production budgets were developed to compare corn silage-alfalfa (CS-A) rotation sequences utilizing conventional spring seeding or interseeding for alfalfa establishment. Our analyses employed average prices from 2012-2017 and recommended management practices from the upper Midwestern, USA such as a cereal rye (Secale cereale L.) cover crop. Interseeded rotations yielded an annual net return (total revenues minus total costs) of $303 to $367 ha-1, with a 6 yr rotation sequence (CS1-CS2-CS3/A1-A2-A3-A4) identified as the most profitable. Conventional rotations provided lower annual net returns of $260 to $320 ha-1 and the most profitable was an 8 yr rotation sequence (CS1-CS2-CS3-CS4-A1-A2-A3-A4). Sensitivity analyses demonstrated that interseeded alfalfa had a robust economic benefit, with increased net returns obtained when the corn yield penalty was limited to less than 20% or the success rate of alfalfa establishment exceeded 49% of attempts for the most profitable interseeded rotation sequence. Additionally, application of a plant growth retardant plus fungicide to interseeded alfalfa in the most profitable rotation sequence provided a net economic benefit if it increased the success rate of alfalfa establishment by >16%. Interseeding alfalfa into corn silage is an economically beneficial practice that could enhance profitability of corn silage-alfalfa based cropping systems in temperate regions under recent economic conditions.