Biological fertilizers, also known as biofertilizers, are natural substances that enhance soil fertility and plant growth. They contain living microorganisms, such as bacteria and fungi, which help improve nutrient availability and promote healthy root development. These fertilizers can be derived from various sources, including compost, manure, and specific plant extracts. Using biological fertilizers can lead to sustainable agriculture by reducing the need for chemical fertilizers. They improve soil structure, increase microbial activity, and enhance the overall health of the ecosystem. Common examples of biofertilizers include Rhizobium for legumes and mycorrhizal fungi for various plants.