INFLUENCE OF SYMBIOTIC, ORGANIC AND MINERAL NITROGEN ON YIELD AND QUALITY OF SOYBEAN

Under semiarid conditions of Karaj/Iran the influence of manure and fertilizer, each in three entries, in combination with inoculum on yield and yield components of the soybean variety Williams was tested. Fertilizer was applied at 0, 30 and 60 kg N/ha and manure at 0, 5 and 10 t/ha. A rotted, very dry cow dung was used. Inoculants Helibioagri, Grip and Azofix were used besides an uninoculated control. The results were heavily influenced by the climate of the two years of experiments. The first year - 1992 - was unusually wet and cold, and the planting delayed. The influence of manure and nitrogen fertilizer shows controversial effects on yield in the two years, which was also found for most yield components. The greatest influence could be reached by the different treatments with inoculum. The highest yield was found with Helibioagri with 3446 kg/ha (180% of uninoculated) in 1992 and with Azofix with 4180 kg/ha (255% of uninoculated) in 1993. With increasing amount of fertilizer 1992 the yield decreased while 1993 the manure application showed a gain in yield. The most visible influence on protein and oil content was reached by inoculation. The inoculation outyielded the control by 9.2% and 10.3% in the two years, with a spectrum between 25.6% and 36.4%. The adversely influenced oil content shows values between 20.8% and 24.9% with a decrease of 15% and 12% due to inoculation. A similar correlation between yield and yield components (number of pods and nodes and thousand kernel weight) was found in both years. The same trend, but on quite different levels in the two years shows the influence of the number of pods. But the number of nodes follow the same regression in both years.