Nitrogen Cycle in Agriculture: Biotic and Abiotic Factors Regulating Nitrogen Losses

The benefits that nitrogen (N) fertilizers represent for the sustenance of the population at the global scale are undeniable. However, the nitrogen-use efficiency (NUE) in agriculture (the amount of nitrogen retrieved in food produced per unit of nitrogen applied) is extremely low. Volatilization, leaching, soil erosion and denitrification processes result in the loss of most of the applied N, which isleading to field recoveries that rarely exceed 50%. These losses that are driven by both biotic and abiotic factors cause several environmental damages including water eutrophication, greenhouse gases production and soil acidification. This chapter aims to provide an overview of the nitrogen cycle in agriculture and the N losses derived from the use of N-fertilizers as well as to give a comprehensive description of the factors that drive these losses including soil pH, soil temperature, soil moisture and oxygen availability, soil-carbon (C) content, the C:N ratio of applied substrates, soil pore spaces and composition of microbial communities.