Beneficial Microbes for Agriculture and Biosphere Protection

In addition, the production of nitrogen fertilizer by the Haber Bosch process involves the liberation of high quantities of CO2 (ca. 275 million tons per year) at the expense of fossil fuels such as natural gas and coal. On the other hand, the efficiency of the nitrogen fertilizer applied is relatively low and an important source of environmental pollution, although it is widely accepted that application of N fertilizers has decisively contributed to pace food production with human population growth in the last decades.

Paradoxically, agriculture productivity is very sensitive to climate change, therefore this vicious cycle must be broken and a series of actions should be considered. Some of them should address a more efficient use of current N fertilizers, but other serious actions should be directed to take advantage of the different soil microbial activities and plan-microbial interactions related to plant nutrition and plant health. One of them is to put on value the process of biological nitrogen fixation (BNF) through more sustainable technologies that reduce the undesired effects of chemical N fertilization of agricultural crops, as recommended by the 2011 Edinburg Declaration on Reactive Nitrogen. BNF, the microbial reduction of atmospheric nitrogen to ammonia which, contrary to the industrial process, has significantly lower economic and environmental costs, is restricted to some prokaryotes and archaeas which are able to break the strong triple bound within the N2 molecule either free-living or in symbiosis with plants like legumes. Wider legume adoption, supported by coordinated legume breeding and inoculation programs are approaches at hand.

Also available are inoculants based on diverse microbes (bacteria and fungi) that help reduce the crop needs of chemical fertilization and contribute to their mineral nutrition, water provision and health.

Engineering cereals with the capacity to fix nitrogen, either by themselves or in symbiosis with nitrogen-fixing microbes, together with the use of cell free nitrogenase system as an environmental clean synthesis of ammonia, are additional attractive future approaches which nevertheless require more intensive and internationally coordinated research efforts. Although nitrogen-fixing plants may be less productive, at some point agriculture must significantly reduce the use of warming (chemically synthesized) N and give priority to the BNF and other microbial biotechnologies, if it is to sustain both food production and environmental health for a continuously growing human population.