Influence of azolla with different levels of urea in rice production in south west bangladesh

A pot experiment was conducted on Satla soil series in Terokhada Upazilla, Khulna during the boro season (February to June) to see whether Azolla (biofertilizer) could be grown together with BRRI dhan 28 and to compare the effect of the recommended dose of N (100 kg N ha-1) with that of different combinations of urea and Azolla (all treatments having the recommended doses of P, K, S and Zn). The experiment was laid out in a completely randomized design with 5 treatments and 4 replications. Azolla pinnata applied 0.2 kg m-2 grew well with BRRI dhan 28. The highest amount of grain yield of 2.35 t ha-1 was produced by the application of 75 Kg N ha-1 with Azolla. One layer of Azolla with 50 kg ha-1 urea-N produced almost same amounts of grain. Thus the rate of 0.2Kg m-2 Azolla inoculums as N source along with 50-75% Urea-N ha-1 appeared to be a good practice in reducing the use of costly urea (chemical N source) fertilizer by about 25-50%.