Nitrogen fertilization and stress factors drive shifts in microbial diversity in soils and plants

Global demand for agricultural crops is increasing, and global food production is already dependent on intensive management. Despite efforts to improve production through genetically modified crop varieties and fertilization and pesticide management strategies, yields are stagnant or in declinining. Fertilization is a common farming practice in which organic and inorganic fertilizers are used primarily to improve plant nutrition and crop productivity. However, long-term nitrogen (N) fertilization alters the community and diversity of soil microorganisms and plant endophytes. Nitrogen inputs inhibits or excludes services provided by microbial symbionts making plants dependent on applied mineral nutrients, susceptible to disease and less resistant to abiotic stress resulting in lower crop yields. Stress in plants also triggers changes in plants that affect microbes in soils and in plants. This review describes how inorganic/organic N-fertilization induces shifts in bacterial communities in soils and plants.