An overview of underutilized benefits derived from as a promising biofertilizer in lowland rice production.

Currently, there is no doubt that can compensate for the nitrogen requirements of rice in different agroecological zones. Compared to synthetic N-fertilizers, Azolla has various positive impacts on lowland rice production, including improving soil fertility, minimizing weeds, increasing soil organic carbon, improving microbial biomass, and thus nutrient cycling and enhancing rice growth and yield. However, has not been accepted globally by rice farmers for field use and so far, farmers are relying on increasing rates of synthetic N fertilizers instead of taking advantage of which will improve long-term soil fertility and health. This systematic literature review and scientific evidence could help policymakers, scientists and researchers to understand the benefits, limitations, and innovative ways of utilizing as a cost-effective and eco-friendly amendment in rice production. The paper uses Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) method to review the hidden potential of as a biofertilizer in paddy and summarizes its benefits and problems by collecting information from different sources and presenting under different subheadings such as critical factors affecting growth and nitrogen fixation, nitrogen fixation of and their contribution in soil health, release and availability of -N to rice, amounts and time of inoculation, influence of on ammonia volatilization, contribution of to yield and yield components of rice, and impact of on weed emergence in rice cropping system. Literature indicated that the use of as green manure incorporated before rice transplanting or grown together with rice and left until a few days of harvest alone or in combinations with other synthetic fertilizers in the lowland rice production saved the nitrogen requirement of rice up to 60 kg N ha, it enhances the availability of nutrients, improves physiochemical properties of soils, minimizes soil salinity, reduces the soil pH, and minimize weed germination. However, it was observed that incorporating as green manure is labor-intensive, and maintaining the inocula and phosphorous requirement are major restrictions for farmers. Therefore, understanding mechanism of spore production, educating farmers on cheaper alternative ways of application, and testing different species of over different agroecological zones will help in maintaining biomass and applying it at low cost for further environmental conservation.