title: Measurement of symbiotic nitrogen-fixation in leguminous host-plants grown in heavy metal-contaminated soils amended with sewage sludge.
abstract: Rates of nitrogen fixation by Rhizobium in symbiosis with leguminous host-plants including white clover, broad bean and peas have been established in soils that have been amended experimentally with heavy metal-contaminated sewage sludges. Results from 15N-dilution experiments for the measurement of N2 fixation have shown that adverse heavy metal effects are apparent on symbiotic N2 fixation rates for white clover grown in inter-specific competition with ryegrass under mixed sward conditions, compared to white clover grown in pure sward. Further experiments on broad bean and pea indicated a significant, but minor-inhibitory metal-related effect on the rate of N2 fixation compared to untreated soils and soils amended with a relatively uncontaminated sludge. The implications of the results with respect to sludge utilisation in agriculture are discussed.
authors.affiliation: Environmental Science Division, Institute of Environmental and Biological Sciences, Lancaster University, Lancaster LA1 4YQ, UK. chejpo@nus.edu.sg
authors.forename: J P
authors.initials: JP
authors.lastname: Obbard
authors.forename: K C
authors.initials: KC
authors.lastname: Jones
mesh_terms: D000383:Agriculture; D007887:Fabaceae / Q000502:physiology*; D019216:Metals, Heavy / Q000009:adverse effects*; D009586:Nitrogen Fixation / Q000187:drug effects*; D010946:Plants, Medicinal; D012231:Rhizobium / Q000502:physiology*; D012722:Sewage; D012989:Soil Pollutants / Q000009:adverse effects*; D013559:Symbiosis
chemical_list: D019216:Metals, Heavy; D012722:Sewage; D012989:Soil Pollutants