Itzigsohn, R., Dept. Plant Pathol. and Microbiol., Otto Warburg Ctr. Agric. Biotech., Hebrew University of Jerusalem, Rehovot, Israel
Burdman, S., Dept. Plant Pathol. and Microbiol., Otto Warburg Ctr. Agric. Biotech., Hebrew University of Jerusalem, Rehovot, Israel
Okon, Y., Dept. Plant Pathol. and Microbiol., Otto Warburg Ctr. Agric. Biotech., Hebrew University of Jerusalem, Rehovot, Israel, Dept. Plant Pathol. and Microbiol., Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel
Zaady, E., Desertification Restoration Ecol. R., Jacob Blaustein Inst. Desert Res., Ben-Gurion University of the Negev, Sede Boker, Israel
Yonatan, R., Department of Natural Resources, Agricultural Research Organization, Volcani Center, Bet Dagan, Israel
Perevolotsky, A., Department of Natural Resources, Agricultural Research Organization, Volcani Center, Bet Dagan, Israel

Inoculation experiments of natural pastures with the rhizobacterium Azospirillum brasilense were conducted in Israel in 1996, in two climatically differentiated regions. These experiments were carried out as part of a project with the objective of estimating the potential of the inoculation technique in improving pasture yields. The effects of inoculation with A. brasilense were compared to P-fertilization and to untreated controls. In two semiarid sites, it was generally observed that both the inoculation and the P-fertilization treatments increased pasture yield as measured by dry weight biomass. It was also found that both inoculation and P-fertilization treatments caused an enrichment in legumes relatively to grasses and forbs. Despite the ecological complexity of these sites and the variability of the data, statistical significance was generally achieved. In a more topographically uniform site, located in a typical Mediterranean climate, the positive effects of A. brasilense inoculation in plant-growth were substantially clear, with final yields duplicated in both inoculation and combined (inoculation and P-fertilization) treatments in comparison to P-fertilization alone and untreated controls. The potential of using A. brasilense for growth promotion of natural pastures is discussed.