Effect of inorganic N fertilizer and organic residue management on the microbial population in the paddy fields [in Bangladesh]
1989
Miyan, M.S. | Islam, A.B.M.S. | Zaman, S.K. | Bhuiyan, N.I.
A study on different groups of bacteria as affected by inorganic N and organic residue management was conducted in Bangladesh Rice Research Institute, Joydebpur during 1987 t. aman season using soils from a long term experiment with t. aman(BR11) - Boro(BR3) cropping pattern. Four rates of N (0,30/40, 60/80, and 90/120 kg/ha) were applied annually for t. aman-Boro cropping pattern and four sources of organic residues (0, cowdung, rice straw and sesbania, at the rate of 5 t/ha on oven dry basis were applied once in a year prior to t. aman crop. After 4 years of cropping, composite soil samples were collected from seven selected treatments to count the microbial populations. The populations of Azotobacter, SO4-reducing bacteria and Fe reducing bacteria were determined by the most probable number method. Inorganic N and organic residue treated plots showed a higher number of Azotobacter, SO4-reducing and iron reducing bacteria than the control (no organic residue) plots. In general the populations of Azotobacter, iron and SO4- reducing bacteria were much higher in soil samples of the organic residue treated plots than in those of the inorganic N treated plots. Sesbania enhanced the population of different groups of bacteria much more than rice straw or cowdung.
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