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ARS Home » Midwest Area » Columbus, Ohio » Soil Drainage Research » Research » Publications at this Location » Publication #385879

Research Project: Agricultural Water Management in Poorly Drained Midwestern Agroecosystems

Location: Soil Drainage Research

Title: Benefits of alfalfa interseeding include reduced residual soil nitrate following corn production

item Osterholz, William - Will
item RUARK, MATT - University Of Wisconsin
item RENZ, MARK - University Of Wisconsin
item Grabber, John

Submitted to: Agricultural and Environmental Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/13/2021
Publication Date: 9/8/2021
Citation: Osterholz, W.R., Ruark, M.D., Renz, M.J., Grabber, J.H. 2021. Benefits of alfalfa interseeding include reduced residual soil nitrate following corn production. Agricultural and Environmental Letters. 6(3). Article e20053.

Interpretive Summary: Nitrate leaching from croplands, including those producing dairy forage, is a major issue of concern for water quality and human health. Corn silage production can result in significant nitrate leaching, but a novel cropping system in which alfalfa is interseeded with corn could help address nitrate losses. This study examined nitrate leaching risk in the interseeded corn/alfalfa system compared to a typical corn-alfalfa rotation. Across several nitrogen fertilizer application rates and times of application it was shown that the interseeded system can significantly reduce residual soil nitrate after corn silage is harvested. The interseeded alfalfa takes up soil nitrate and prevents it from being lost from the field, thus improving environmental outcomes of dairy forage production.

Technical Abstract: Interseeding alfalfa into corn silage can increase forage production but effects on soil nitrate pools remain unknown. We compared soil nitrate pools during and after interseeded alfalfa establishment in corn with pools during production of solo-seeded corn followed by spring seeded alfalfa. Nitrogen fertilizer was applied at three rates as a preplant broadcast or a 50:50 split between preplant broadcast and banded sidedress applications. During corn growth soil nitrate levels from 0-30 cm were increased by higher N rates but were usually similar for both production systems. However, growth of interseeded alfalfa after corn harvest resulted in substantially lower residual fall and spring soil nitrate levels to a 90 cm depth, particularly under the highest N rate. Additionally, interseeded alfalfa influenced spring nitrate stratification by reducing nitrate in deeper horizons and increasing nitrate in the surface horizon. Interseeded alfalfa can thereby reduce thereby reducing the risk of N leaching.