Dried Azolla pinnata as a supplementary nitrogen source for lowland rice production in a Calcic Natraquert

A pot experiment was conducted in the experimental field of the University of Ghana, Legon to examine the effectiveness of dry Azolla as N source in flooded rice field. The treatments included incorporating fresh Azolla (FA at 90 kg N/ha), dry Azolla (DA at 90 kg N/ha), dry Azolla + Ammonium sulphate (DA at 45 kg N/ha + AS at 45 kg N/ha), fresh Azolla + dry Azolla (FA at 45 kg N/ha + DA at 45 kg N/ha), ammonium sulphate (AS at 90 kg N/ha) and a control (C at 0 kgN/ha). The treatments were applied 8 days after transplanting rice. Results showed that the DA + AS treatment, that is, the treatment where dry Azolla + ammonium sulphate were used to fertilize the rice had the highest dry weight and total N yield followed by the treatment AS. Total N for the DA + AS treatment was 36.67% over the control whilst that for the AS was 25% over the control. Dry Azolla has the potential for supplementing for the nitrogen requirement for irrigated rice.