The influence of long-term application of mineral fertilizers on the effects of inoculation with Bradyrhizobium japonicum

Abstract

The influence of long-term application of mineral fertilizers (25 years) on the effectiveness of inoculation and soybean yields was studied in the course of 1991, 1992 and 1993. Trials with the soybean cultivar Kolubara were established at Rimski Šančevi. Indicators used in monitoring the effect of the long-term fertilizer application (a - no fertilization, b - N₇₀ P₆₀ K_40,, c - N₁₁₀ P₉₀ K₆₀, d - N₁₅₀ P₁₂₀ K₈₀) were the dry matter mass and nitrogen (N) content as well as yields and the number of nodules per root. The greatest dry matter mass and the highest N content and seed yield were achieved in the inoculated treatments in the first year of the study. The effects of the long-term fertilizer application and inoculation were on the decline in the second year of the study, only to get completely lost in the third. At the conclusion of the third year, the greatest dry matter mass and highest N contentwere observed in the treatment with the lowest N rate (70 kg Nha^-1) as well as in inoculated treatments with no N applied.