Submitted to: Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 18, 2002
Publication Date: July 25, 2002
Interpretive Summary: Extensive areas of saline deposits are rendering agricultural soils in the western United States unsuitable for cropping. Identifying salt-tolerant plant species to grow in salt-affected soils or to be irrigated with saline water may increase crop productivity for owners of salt-affected lands. Narrow-and broadleaf birdsfoot trefoil and tall fescue, all potential forage species, were grown in a greenhouse under saline soil conditions that simulated those found in southeast Colorado. Saline conditions did not significantly reduce DM yields for any of the forage species. Overall, tall fescue produced almost twice as much DM yield as both narrow-and broadleaf birdsfoot trefoil. The salt ions sodium (Na) and chloride (Cl) were highest in both birdsfoot trefoil species grown under saline conditions, whereas calcium (Ca) concentrations were highest in tall fescue. Soil salinity increased after 319 days of irrigation with saline water. High saline soils may require salt management practices, e.g., leaching, applying gypsum, for long-term use of poor quality water under field conditions.
Technical Abstract: Potential forage crops were evaluated under simulated saline conditions found in southeast Colorado. Due to elevated salinity levels in both the soils and in the irrigation waters of this region identifying salt tolerant crops for sustained productivity is important. The objective of the greenhouse study was to evaluate the salt tolerance of tall fescue and broad-and narrowleaf birdsfoot trefoil irrigated with saline water (up to 6 dS/m) and grown in either a non-saline (electrical conductivity (Ec) of < 1.8 dS/m) or in a saline soil (EC of 7 dS/m) typical of this region. After 319 days, tall fescue produced almost twice as much dry matter (DM) as either species of birdsfoot trefoil. Dry matter yields were not significantly reduced by saline water for any of the tested plant species. Herbage Ca concentrations were as high as 2% in both species of broadleaf trefoil and were as low as 0.2% in tall fescue. In contrast, Cl concentrations were as high as 2.8% in tall fescue and as low as 0.5% in either broad- or narrow leaf birdsfoot trefoil. Irrigation with saline water increased the soil EC to as high as 15 dS/m. These high soil salinity levels infer that salt management practices, e.g., leaching, applying gypsum, will be essential for growing forage crops with saline water on saline soils in the southeast region of Colorado.