This chapter provides a brief discussion of Nickel (Ni) as it relates to soils, soil microbiology, and Rhizosphere, plants with some perspective scattered throughout. Ni was first recognized as a unique element in 1751 upon its isolation by the Swedish mineralogist Axel Fredrik Cronstedt. Industrial and agricultural activity, the burning of fossil fuels and the weathering of geologic sources of Ni has led to the introduction of Ni into soil and aquatic environments. Ni-bearing phyllosilicate and/or layered double hydroxides precipitates possess large stability fields indicating their relative importance to controlling Ni solubility under a range of conditions. Ni is thought to be more readily available in soils formed from partially serpentinized peridotite as opposed to soils formed from more highly serpentinized parent materials. The chapter presents the discussion of Ni in soils and plants with the most notorious of geogenically Ni-enriched ecosystems—the serpentine soils. Serpentine soils are part of a larger, distinct group of soils known as ultramafic soils.