|Blank, Robert - Bob|
Submitted to: Applied Soil Ecology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/1/2009
Publication Date: 6/15/2009
Citation: Goergen, E., Chambers, J., Blank, R.R. 2009. Effects of Water and Nitrogen Availability on Nitrogen Contribution by the Legume, Lupinus argenteus Pursh. Applied Soil Ecology. 42:200-208. Interpretive Summary: Nitrogen fixing plant species are important components in the nitrogen budgets of Great Basin soils. In a greenhouse study, we examined the interacting affects of water and nitrogen availability on the growth and tissue N concentration of silver lupine (Lupinus argenteus) and native legume. Data indicate that silver lupine had the potential to significantly increase soil nitrogen availability.
Technical Abstract: Nitrogen-fixing species contribute to ecosystem nitrogen budgets, but background resource levels influence nodulation, fixation, and plant growth. We conducted a greenhouse experiment to examine the separate and interacting effects of water and N availability on biomass production, tissue N concentration, nodulation, nodule activity, and rhizodeposition of Lupinus argenteus (Pursh), a legume native to sagebrush steppe. Plants were grown in a replicated, randomized block design with three levels of water and four levels of N. Additional water and N increased biomass except at the highest N level. All plants formed nodules regardless of treatment, but plants grown without N had the largest, most active nodules. Organic N was deposited into the rhizosphere of all plants, regardless of treatment, indicating that Lupinus can influence N availability while actively growing, even under water stress. High tissue N concentrations and low C:N ratios indicate that Lupinus also can provide substantial amounts of N through litter decomposition. The ability of Lupinus to affect N availability and cycling indicates that it has the potential to significantly influence community composition within the sagebrush steppe.