Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: June 25, 1995
Publication Date: N/A
Technical Abstract: Deeply rooted legumes, like alfalfa (Medicago sativa L.), provide the opportunity to remediate contaminated sites by removing leached nitrate from the subsoil. The objectives of this study were to evaluate the ability of different alfalfa germplasms to remove nitrate from subsoil and to assess the use of bromide as an indicator for nitrate absorption in alfalfa. Under controlled environment conditions, the uptake and within-plant distribution of assimilated nitrate and bromide were strongly correlated. In the field, a subsoil irrigation system was installed at the 50-cm depth on a sandy, mixed Udorothentic Haploboroll at Becker, MN. We characterized the ability of eight alfalfa germplasms differing in their symbiotic efficiency, root system architecture, and dormancy to take up subsoil nitrate. Plants were exposed to 20 mM nitrate in the subsoil irrigation water enriched with 3 mg/L bromide during the first regrowth and dwith 15N during the second regrowth of the first production year. Results confirm differences in efficiency of nitrate removal. The relationship of bromide and nitrate uptake under field conditions will be discussed.