Preface for Small-Molecule Activation: From Biological Principles to Energy Applications. Part 2: Small Molecules Related to the Global Nitrogen Cycle

The nitrogen cycle is among the most significant biogeochemical cycles on Earth because nitrogen is an essential nutrient for all forms of life. The largest contributor of nitrogen in the cycle is atmospheric dinitrogen (N_2), which is generally unavailable to plants by direct assimilation. Hence, access to fixed forms of nitrogen constitutes in many cases the most limiting factor for plant growth. This is in sharp contrast to carbon, which is easily taken up by plants from the atmosphere by fixing gaseous carbon dioxide (CO_2). The availability of nitrogen (and water) hence limits the ability to produce sufficient crops to feed our planet's growing population.