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 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 N budgets and community composition within the sagebrush steppe.
Keywords
rhizodeposition,
symbiotic nitrogen fixation,
silver lupine,
sagebrush steppe
Citation
Goergen, Erin; Chambers, Jeanne C.; Blank, Robert. 2009. Effects of water and nitrogen availability on nitrogen contribution by the legume, Lupinus argenteus Pursh. Applied Soil Ecology. 42(3): 200-208.