Nitrogen Fixation Using Symbiotic and Non-Symbiotic Microbes: A Review Article
Mamo Bekele, Getachew Yilma
Abstract
Nitrogen (N) is one of the key drivers of global agricultural production and needs 150-200 million tons each year by plants in agricultural systems to produce the world’s food, animal feed and industrial products. Hence, to minimize this problem industrially producing nitrogen fertilizer is necessary. However, this industrially produced nitrogen fertilizer affect the world ecosystem through different mechanisms and effective exploitation and utilization of biologically fixed nitrogen in agricultural systems is necessary. This naturally fixed nitrogen minimizes the rate of cost of crop production, urea volatilization and is the sustainable soil fertility maintenance. Despite the importance of biological nitrogen fixation is sustainable and environmentally friend approach, some researches were done on legume crops through exploring variety specific rhizobia species for legume crops and shortage of information on free living nitrogen fixer of bacteria species for cereal crops which will be the future concerned research. This paper review discusses biological nitrogen fixation mechanism symbiotically and non-symbiotically either through free living bacteria or associative with host plant. It also focused on types of bacteria in which fix atmospheric nitrogen in cereal crops and factors affecting biological nitrogen fixation in lesser amount.