Effects of Bio- and Chemical Nitrogenous Fertilizers on Yield of Anise Pimpinetta anisum and Biological Activities of Soil Irrigated with Agricultural Drainage Water

摘要

TWO field experiments were conducted (during winter seasons of 2002 and 2003) to investigate whether chemical nitrogen fertilizer sources and/or N_2 fixing bacteria (Azotobacter and Azospirillum) using agricultural drainage water could affect anise plants quantity and quality. Besides, the effect of different nitrogen sources on biological activity in the rhizosphere of this medicinal plant. The results proved significant difference among the treatments with regard to the nitrogen forms and activities of rhizosphere bacteria. Inoculation with N_2 fixing bacteria with half doses of chemical nitrogen fertilizers affected the quantity and quality of anise plants yield. The mean values of combination between chemical fertilizers and N_2 fixating bacteria were more or less equal and in sometimes higher than those obtained when using the recommended mineral N dose with any form of nitrogen. On the other hand, microbiological analysis indicated that the plants with high N content harbored higher populations of nitrogen-fixing bacteria and highest enzymatic activities of soil. Under different form of N fertilizer, the rhizosphere of anise plants, which differed in biological activities and their bacterial densities, harbored almost identical population densities of nitrogen-fixing bacteria. Interestingly, the total bacterial counts were greatly stimulated following the application of bio- and half dose of ammonium nitrate as nitrogen fertilizer.