Potential of using algae as fertilizers and plant-stimulants for an ecofriendly and sustainable agriculture

Algae are photosynthetic organisms that can utilize sunlight as an energy source to convert carbon dioxide and inorganic molecules like nitrates and phosphates into complex organic molecules and produce oxygen. Algae contain all the essential nutrients for plants, such as Nitrogen (N), Phosphorus (P), and Potassium (K), that can be used as fertilizers. They also contain growth hormones and other beneficial substances which can promote plant growth and soil health. Algae are considered organic, safe to use, and more environmentally friendly compared to chemical fertilizers. Moreover, algae can be mass-produced in wastewater, which is a good source of N, P, K, and other nutrients. This thesis attempts to study the benefits of using algal biomass generated in wastewater treatment facilities (WWTF) as a fertilizer supplement and stimulant to promote soil and plant health. First, we identified factors contributing to plant and soil health, the detrimental effects of synthetic fertilizer production, and their effect on the environment, especially greenhouse gas (GHG) emissions and water pollution. Second, we determined the composition of algal biomass for their NPK, heavy metals, and components such as crude protein, fat, fiber, ash, and phytohormones. Third, we evaluated the benefits of using algal biomass as a fertilizer while growing cotton plants in a growth chamber. Fourth, we evaluated gene expressions and antioxidant activities in cotton plants. Our results show that the cotton plants were healthy when algal biomass was combined with synthetic fertilizer. We hypothesize that the presence of NPK, essential minerals, and phytohormones in algal biomass are responsible for significantly boosting cotton plant growth. The use of algae pellets as a fertilizer offers a sustainable alternative, reducing the dependency on synthetic fertilizers, which can reduce GHG emissions and benefit our environment.