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Soybean inoculation: Dose, N fertilizer supplementation and rhizobia persistence in soil

Albareda, Marta, Rodríguez-Navarro, Dulce Nombre, Temprano, Francisco J.
Field crops research 2009 v.113 no.3 pp. 352-356
Glycine max, soybeans, Sinorhizobium fredii, Bradyrhizobium japonicum, root nodules, symbionts, symbiosis, nitrogen fertilizers, fertilizer rates, application rate, field experimentation, crop yield, dry matter partitioning, soil bacteria, mortality, Spain
The effect of rate of application of Sinorhizobium (Ensifer) fredii SMH12 or Bradyrhizobium japonicum USDA110 inoculants on grain yields of soybean [Glycine max (L.) Merrill] cv. Osumi was studied in a field experiment laid out in Southern Spain. All inoculant doses tested (10⁴, 10⁵, 10⁶ and 10⁷ rhizobia/seed) produced higher seed yields than those obtained in un-inoculated plots. Increments in nodule dry weight, seed yield and seed N content were observed when the number of rhizobia applied to seed increased from 10⁴ up to 10⁷. The addition of N fertilizer to inoculated soybean plants (50kg N/ha applied at R1 or R4 stage) did not increase seed yields in comparison with treatments that were only inoculated. Survival of strains SMH12 and USDA110 was monitorized for three years in two different soils of Southern Spain after soybean inoculation. Rhizobia survival was varied dependent on the soil and the rhizobia strain used.