A field experiment was conducted at EL-Kalubia governorate at the
season (June - October 2001) to study the potential of Azolla application as
bio-nitrogen source in comparison with the mineral nitrogen fertilizer as urea
as well as their effect on soil organic matter. Results reveal that Azolla
significantly increased rice yield (Var. Sakha 102) and soil organic carbon.
Increase in yield was 89.5 % (60 kg N fed" as urea), 81.5 % (60 kg N fed"
as Azolla₁and 92.1 % (30 kg N fed-' as urea + 30 kg N fed" as Azolla). Sixty
kg N fed- as Azolla was almost equivalent the application of 60 kg N fed"
as urea. The combination of urea and Azolla 30 kg N fee" each resulted in
grain yield higher than that obtained with urea or Azolla alone but not
significantly different from that obtained with 60 kg N fed" as urea. The
increase of rice grain yield was associated with the increase in the number of
panicles hill-' and the grain weight. The soil organic carbon increased over
the control by 28 % for Azolla treatment, 41.1 % for urea-Azolla combination
and did not change with urea.