Nitrogen Mineralization of Azolla Mexicana Applied As Fertilizer Compared to Compost and Cyanobacterial Fertilizers.

The free-floating freshwater fern Azolla has the potential to supply nitrogen to non-paddy crops if harvested and applied to soil for that purpose. Past research on Azolla as a source of N have focused on paddy rice systems only. The objective of this study was to determine the N mineralization rates of compost and cyanobacterial fertilizers compared to an Azolla species native to the Great Plains. A 140-d incubation study was carried out, and fertilizers were applied to a Fort Collins loam, clay loam at 50 kg N ha^-1. The treatments in this study were control (no fertilizer), compost (Compost), cyanobacteria (Cyano), cyanobacteria flocculated with moringa (Cyano + Moringa), Azolla grown in dechlorinated tap water (Azolla) and Azolla grown in a liquid medium known as Watanabe solution in order to maintain Azolla in a vegetative state (Azolla + Watanabe). Preliminary results show that Soil NH₄⁺-N concentration for all treatments tended to peak at day 56 and then declined. The compost treatment tended to have higher Soil NH₄⁺-N concentration compared to the other treatments for the first 28 days. Soil NO₃^- -N concentration for all treatments tended to increase but Azolla + Watanabe treatment recorded a slightly higher NO₃^- -N concentration than the other fertilizers throughout the study. Further work will include calculation of N mineralization rates and statistical analysis.