Biofertilizers: An ecofriendly technology for nutrient recycling and environmental sustainability

Highlights

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  Agriculture plays an important role in a country's economy. In modern intensive agricultural practices, chemical fertilizers and pesticides are applied on large scale to increase crop production in order to meet the nutritional requirements of the ever-increasing world population. However, rapid urbanization with shrinking agricultural lands, dramatic change in climatic conditions and extensive use of agrochemicals in agricultural practices has been found to cause environmental disturbances and public health hazards affecting food security and sustainability in agriculture. Besides this, agriculture soils are continuously losing their quality and physical properties as well as their chemical (imbalance of nutrients) and biological health due to indiscriminate use of agrochemicals. Plant-associated microbes with their plant growth- promoting traits have enormous potential to solve these challenges and play a crucial role in enhancing plant biomass and crop yield under greenhouse and field conditions. The beneficial mechanisms of plant growth improvement include enhanced availability of nutrients (i.e., N, P, K, Zn and S), phytohormone modulation, biocontrol of phytopathogens and amelioration of biotic and abiotic stresses. This plant-microbe interplay is indispensable for sustainable agriculture and these microbes may perform essential role as an ecological engineer to reduce the use of chemical fertilizers. Various steps involved for production of solid-based or liquid biofertilizer formulation include inoculum preparation, addition of cell protectants such as glycerol, lactose, starch, a good carrier material, proper packaging and best delivery methods. In addition, recent developments of formulation include entrapment/microencapsulation, nano-immobilization of microbial bioinoculants and biofilm-based biofertilizers. Thus, inoculation with beneficial microbes has emerged as an innovative eco-friendly technology to feed global population with available resources. This review critically examines the current state-of-art on use of microbial strains as biofertilizers in different crop systems for sustainable agriculture and in maintaining soil fertility and enhancing crop productivity. It is believed that acquisition of advanced knowledge of plant-PGPR interactions, bioengineering of microbial communities to improve the performance of biofertilizers under field conditions, will help in devising strategies for sustainable, environment-friendly and climate smart agricultural technologies to deliver short and long terms solutions for improving crop productivity to feed the world in a more sustainable manner.

Abstract

Modern intensive agricultural practices face numerous challenges that pose major threats to global food security. In order to address the nutritional requirements of the ever-increasing world population, chemical fertilizers and pesticides are applied on large scale to increase crop production. However, the injudicious use of agrochemicals has resulted in environmental pollution leading to public health hazards. Moreover, agriculture soils are continuously losing their quality and physical properties as well as their chemical (imbalance of nutrients) and biological health. Plant-associated microbes with their plant growth- promoting traits have enormous potential to solve these challenges and play a crucial role in enhancing plant biomass and crop yield. The beneficial mechanisms of plant growth improvement include enhanced nutrient availability, phytohormone modulation, biocontrol of phytopathogens and amelioration of biotic and abiotic stresses. Solid-based or liquid bioinoculant formulation comprises inoculum preparation, addition of cell protectants such as glycerol, lactose, starch, a good carrier material, proper packaging and best delivery methods. Recent developments of formulation include entrapment/microencapsulation, nano-immobilization of microbial bioinoculants and biofilm-based biofertilizers. This review critically examines the current state-of-art on use of microbial strains as biofertilizers and the important roles performed by these beneficial microbes in maintaining soil fertility and enhancing crop productivity.

Graphical abstract