Liquid biofertilizers from seaweeds: A critical review

Abstract

Seaweeds are an economical and natural source of bio-fertilizer and bio-stimulants. The extracts of marine macroalgae are widely used as liquid bio-fertilizers in crop production. The application of seaweed extracts was found to affect the growth and yield of many crops positively. The seaweed liquid fertilizers are also rich in micronutrients, vitamins, amino acids, and antibiotics. Alginate and other polysaccharides found in seaweed extracts are known to stimulate root growth and trigger the defense mechanisms of plants. Application of seaweed liquid fertilizer (SLF) to soils augments soil fertility by improving the availability of macronutrients and health by enhancing microbial activity. Many marine algae belonging to green algae (Chlorophyta), brown algae (Phaeophyta), and red algae (Rhodophyta) are commonly used to prepare extracts that are used as liquid bio-fertilizers. Exogenous application of SLF is known to improve plants' physiological and biochemical parameters and induces abiotic stress tolerance in treated plants. This technology can be integrated with organic farming for sustainable agriculture. This paper reviews the literature supporting evidence for applying seaweed extracts as liquid biofertilizers and their effect on growth, physiology, and plant yield.