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).

Azolla as a Nutrient-Rich Feed Supplement for Livestock: Enhancing Health and Productivity

“…For optimal Azolla growth, the pH of the water used for cultivation should be between 4.5 and 7 according to multiple sources (da Silva et al, 2022;Adzman et al, 2022). While Azolla can survive in a broader pH range of 3.5 to 10, its growth will be strongest when the water pH is in that 4.5 to 7 range.…”

Azolla Plant Production and Their Potential Applications

“…Azolla is a macrophyte that grows well in Malaysia's climate. Its ideal growing conditions were discovered to be a water depth of 20 cm, a nutrient concentration of 812.5 ppm, a pH level of 7.0, an average daily temperature in Malaysia ranging between 21 °C and 32 °C, and 100% sunlight exposure [32]. Te maximum growth rate of Azolla fliculoides is achieved in 2.1 days at a temperature of 22 °C, a light intensity of 20 lx, a humidity of 75%, and a pH of 6.4.…”

A Review on the Use of Azolla Meal as a Feed Ingredient in Aquatic Animals’ Diets

“…Azolla has been used for centuries as a natural fertilizer for rice paddies in Asia, including China and Vietnam [16]. Its symbiotic relationship with cyanobacteria allows for the fixation of atmospheric nitrogen [17,18,19], which is then transferred to the soil when the plants are incorporated into the rice fields [20]. In recent years, Azolla has gained attention as a potential feed source for aquaculture due to its high protein content and ability to grow rapidly.…”