Two field experiments were carried out at EL- S cyanobacteria and Azona as nitrogen source sharing mineral nitrogen fertilizer in rice production, in comparison wilh the use of the full recommended nitrogen dose (60 kg N fed"). Results reveal thai AzoHa inoculated to rice was superior than cyanobacteria.
Increasing nitrogen level up to 60 kg N fed" increased significantly rice grain and
straw yields. The combination of either cyanobacteria or Azolla with mineral nitrogen
was more beneficial than the use 01 mineral nitrogen alone. Forty kg N (e rice yield not significantly different from that attained due to 60 kg N fed". Same
treatment lead to increases in N-uptake for grain and straw, Soil biological activity
which is represented by soit total bacterial count, total fungi, lotal actinomycetes,
dehydrcgenase activity and carbon dioxide evolution. Generally, both cyanobacteria
and Azoi/a can Partially substitute nitrogen in rice cultivation with priority to Azolla.
saving the high cost of mineral nitrogen fertilizer by about 60 % and reduced the
hazards resulted from the extensive use of mineral nitrogen fertilizers.