The NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. for atmospheric chemistry. Here we review the current knowledge on 60 processes involved in the formation and consumption of NO in soils, the 61 importance of NO for the physiological functioning of different organisms, 62 and for inter-and intra-species signalling and competition, e.g. in the 63 rooting zone between microbes and plants. We also show that prokaryotes 64 and eukaryotes are able to produce NO by multiple pathways and that 65 unspecific enzymo-oxidative mechanisms of NO production are likely to 66 occur in soils. Nitric oxide production in soils is not only linked to NO 67 production by nitrifying and denitrifying microorganisms, but also linked to 68 extracellular enzymes from a wide range of microorganisms. 69