Abstract:
Azolla tissue contains 5% N, which is slowly released into the soil upon decomposition. Timing of
incorporation is therefore important for maximum benefit to a crop. The effect of time to incorporate
Azolla biomass on growth and yield of rice was investigated in Mwea-Kenya. Treatments consisted of
7.5 t ha
-1
Azolla applied at 21 days after transplanting
(DAT) and 30 kg N ha
Azolla biomass applied at transplanting, 7.5 t ha
-1
inorganic N applied in splits at O, 21 and at 55 DAT. There were control
treatments without Azolla and without inorganic N application. The treatments were laid out in a
Randomized Complete Block Design (RCBD) with three replications. Phosphorus and potassium were
applied at 50 Kg ha
-1
each as P2O5 and K2O. Plant height and tiller numbers were recorded at 21
(rooting/tillering), 32 (tillering), 42 (maximum tillering), 60 (flowering) and 75 DAT (heading) while yield
parameters were determined at physiological maturity (120 DAT). Data were analysed using SAS
software and means separated using the least significant difference test (p≤0.05). Azolla incorporation
at transplanting significantly enhanced panicle m
-1
, grain weight and grain yield while incorporating it at
21 DAT only significantly enhanced panicle m
-2
. Higher environmental temperatures enhanced Azolla
effect. The effect of Inorganic N significantly increased plant height, tiller number, grain weight and
spikelets panicle
-2
-1
. However, percentage grain filling was reduced. The effect of interaction between
Azolla application and inorganic N was significant on spikelets panicle
and grain weight. Observations
therefore indicate that the effect of Azolla on yield and yield components was more when incorporated
at transpla
