Belowground Nitrogen Transfer from Forage Legumes to Neighboring Grass in Grass-Legume Binary Mixtures
Date
2021-03-16
Authors
Thai, Tram
Issah, Gazali
Arcand, Melissa
Helgason, Bobbi
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Conference Presentation
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Abstract
Legume forages such as cicer milkvetch (Astragalus cicer) and sainfoin (Onobrychis viciifolia) can be an alternative for alfalfa (Medicago sativa) in pasture system because they are non-bloat species. However, there is no information on the N transfer between these legumes to a companion grass. A 15N labeling greenhouse experiment was set up, including 3 binary mixtures [alfalfa, cicer milkvetch or sainfoin with bromegrass (Bromus madritensis)]. Legumes or grass was separately cross-labeled with 98 atom % 15N urea solution (0.2% v/v) by the cotton-wick method, resulting in 6 labeling treatments. Our results confirmed a bi-directional N transfer between legumes and grass species; the flow of N from forage legumes to bromegrass was 4-11 times higher than from the opposite direction. Quantities of legume-N transferred ranged from 0.67 - 5.91% of the aboveground N in companion grass and differed among forage legumes (alfalfa > sainfoin > cicer milkvetch). Alfalfa was 2-4 times more competitive than cicer milkvetch and sainfoin in scavenging inorganic N from bromegrass (1.50 vs. 0.37 and 0.72 mg N, respectively). Our study highlights the contribution of interspecific N transfer to the N economy in legume-based pasture systems and that the contributions vary with legume species. Link to Video Presentation: https://youtu.be/DmXEazYZAoI
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Legume Forages, Nitrogen, Pasture System
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Soils and Crops Workshop