Integrated Management of Chemical and Biological Fertilizers on Reduction of Nitrate Concentration in Spinach

Using of some nitrogen bio-fertilizers,beside of nitrogen fixation and increasing of yield and growth of cropsaccording to producing of growth plant regulators by microorganisms that exist in this fertilizers, reduce environmental problems by balancing use of nitrogen as chemical fertilizers. Bio-fertilizersare containing of nitrogen fixation bacteria from genus of azotobacter and azospirillum. In order to study effect of chemical and biological N fertilizer and as well as coincide use of both of them on yield and nitrate concentration in spinach, this examination was conducted in fall of 2012 in a randomized complete blocks design with 8 treatments and 3 replication. Treatments included of: 1- applying of bio-fertilizer in seed priming 2- applying of bio-fertilizer in irrigation water 3- applying of bio-fertilizer in seed priming applying of bio-fertilizer irrigation water 4- applying of bio-fertilizer in seed priming applying of 46 kg.ha-1 nitrogen (equal 100 kg.ha-1urea) 5- applying of bio-fertilizer in seed priming applying of 92 kg.ha-1 nitrogen (equal 200 kg.ha-1urea) 6- applying of 92 kg.ha-1 nitrogen (equal 200 kg.ha-1urea) 7- applying of 276 kg.ha-1 nitrogen (equal 600 kg.ha-1urea) (conventional condition) and 8- control (no fertilizer use). The results showed that there was a significant difference among treatments in fresh and dry yield of shoot and root and as well as nitrate concentration in shoot at 5% dunkan test. The highest and lowest amounts of above traits was obtained in conventional condition and control respectively. Integrated use of biological fertilizer and urea increased wet yield significantly compared to the control and/or a single use of the biological fertilizer.By raising urea application, fresh and dry yield and nitrate concentration increased, whereas in treatments of bio-fertilizer solely, these traits could not be increased as urea application. Base on this experiment results, although, according to high Fertilization Efficiency of spinach, the highest spinach wet and dry yield was obtained in conventional condition (600 kg.ha-1 urea), but according to the probable destructive effect of applying of this amount of urea, it’s suggested that in another trial, effect of lower rates of urea and bio-fertilizer should studied.