Preliminary study on Azolla cultivation and characterization for sustainable biomass source

Abstract

Azolla is a freshwater fern that belongs to the Azollaceae family. It is easy to grow and is highly productive. It can fix atmospheric nitrogen due to the presence of Anabaena azollae. Azolla has been applied to the rice field as a classic fertilizer. It is a good source of protein and contains almost all essential amino acids and minerals. Various research has been done and is still ongoing to determine the capability of Azolla as a phytoremediator and to be used as a sustainable bioenergy source. This preliminary study investigated the ideal environment for Azolla cultivation in Malaysia (humid weather throughout the year with average daily temperature across Malaysia between 21°C and 32°C). To the best of our knowledge, there is no research conducted in Malaysia to study the optimum environment for Azolla cultivation. Therefore, determining the optimum condition for growing Azolla was done by manipulating parameters: water depth, nutrient concentration, pH, and sunlight exposure. Meanwhile, chemical compositions (moisture, crude protein, crude fat, ash, crude fibre, carbohydrate and energy) were determined using proximate analysis. Results obtained showed that Azolla growth was the best in water depth of 20 cm, the nutrient concentration of 812.5 ppm, pH of 7 and under 100% sunlight exposure. Dried Azolla had 6.38% moisture, 27.1% crude protein, 6.37% crude fat, 14.29% ash, 34.29% crude fibre, 45.86% carbohydrate and 349.17 kcal/100 g energy. Based on the result, Azolla cultivated in this experiment could be used as a sustainable biomass source to produce animal feed (high protein content) and bioenergy (high fibre content).