Biological nitrogen fixation (BNF) is the major natural process of nitrogen (N) input to ecosystems. To understand how plant invasion and N enrichment affect BNF, we compared soil N-fixation rates and N-fixing microbes (NFM) of an invasive Spartina alterniflora community and a native Phragmites australis community in the Yangtze River estuary, with and without N addition. Our results indicated ...

Biological di-nitrogen fixation (N(2)) is the dominant natural source of new nitrogen to land ecosystems. Phosphorus (P) is thought to limit N(2) fixation in many tropical soils, yet both molybdenum (Mo) and P are crucial for the nitrogenase reaction (which catalyzes N(2) conversion to ammonia) and cell growth. We have limited understanding of how and when fixation is constrained by these nutri...

The exploitation of the soybe an [Glycine max (L.) Merr.] -Bradyrhizobium japonicum symbiosis in varied environments requires an understanding of factors that may affect fixed and soil N assimilation. Temperature affects both soybean maturity and N requirement, and soil N availability. Five soybean varieties belonging to four maturity groups (00, IV, VI, and VIII) and their respective nonnodula...

The study examined the effect of Frankia, macronutrients, micronutrients, mycorrhizal fungi, and plant-growth-promoting fluorescent Pseudomonas sp. on total biomass, nodule weight, and nitrogen fixation of red alder (Alnus rubra) and snowbrush (Ceanothus velutinus) under greenhouse conditions. The soil samples were collected from a 10-year-old clearcut on the H.J. Andrews Experimental Forest, O...

The influence of a supplementary bradyrhizobial inoculation after an initial seed slurry inoculation with the same strain on nodulation and N(2) fixation in soybeans was examined in the greenhouse. The plants were grown in a Typic Eutrocrepts soil: sand mixture containing 25, 65, or 83 mg of N per kg (i.e., native soil N plus N-labeled ammonium sulfate). Harvests were made at early flowering an...

Grain legumes convert atmospheric N2 to reactive N through symbiosis with N2-fixing rhizobia. Biological N2 fixation associated with legumes and the subsequent decomposition of legume residues are the primary processes that replenish N removed by harvest in agroecosystems without the addition of fertilizer N (Galloway et al., 1995, Peoples et al., 1995). Therefore, legumes are often included in...