. A comparison of the use of Azolla and blue-green algal biofertilizers with green manuring, organic manuring and urea in transplanted and direct seeded rice

Abstract

Azolla and blue-green algae (BGA) inoculated in a rice field produced a higher biomass and fixed more nitrogen in transplanted than in direct-seeded rice. Application of Azolla, BGA, corn-posts of Eichhornia and Azolla and green manuring with Sesbania increased tiller numbers, height, grain and straw yields, and nitrogen uptake by rice in both the transplanted and the direct-seeded crop. The growing and incorporating of three Azolla crops with the rice crop produced more grain than the use of other nitrogen sources but the rice crops showed a poor response to inoculation with BGA_ The yield of rice following green manuring with Sesbania or the use of two crops of Azolla after transplanting was similar to that of a crop receiving 60 kg N ha' as urea, but smaller yields resulted from the use of composts of Azolla and Lich¬horn-ia.