EFFECT OF AZOTOBACTER AND ANTIBIOTIC ON SOIL NITROGEN AND RICE SEEDLING GROWTH IN SALINE SOIL

Abstract

Saline soil in general has low nitrogen (N) availability and restricted N uptake. Application of manure and nitrogen fixing bacteria (NFB) in addition to inorganic fertilizer are needed but manure amendment on soil will contribute to increase antibiotic residue in soil. A pot experiment has been conducted to verify the effect of antibiotic-resistance NFB Azotobacter on nitrogen availability and growth of rice seedling in saline soil contaminated with tetracycline and ampicillin. Green house experiment was arranged in factorial Randomized Block Design to examine four concentrations of Azotobacter sp. liquid culture and two kind of generic antibiotic. The first factor was without and with 106 , 107, and 108 CFU g-1 of Azotobacter inoculation, and the second one were antibiotic treatment consisted of tetracycline and ampicillin applied at 1 mg/kg. The results showed that neither Azotobacter nor antibiotic affected plant height, soil pH and EC, as well as Azotobacter population in rice rhizosphere. The interaction effect on both treatment was significant on total nitrogen in soil. This research suggested that Azotobacter maintained soil N when inoculated to soil up to 106 CFU/g and 108 CFU/g irrespective of antibiotic contamination but the bacteria had not yet affect growth of rice seedling in high sodium soil.