Current widespread use and application of nanotechnology will likely spread to agricultural soils. Certain nanoparticles (e.g., MgO) possess biocidal properties when applied to bacteria, however, there is little information related to nanoparticle effects on soil biological processes. The experimental objectives are to evaluate the effects of CuO and MgO nanoparticles on (1) soil microorganisms and (2) soil biological processes of urea hydrolysis and nitrification. Urea or ammonium sulfate was added to soil and inorganic nitrogen levels were monitored for 200 h. Real time PCR was conducted to evaluate gene expression of urease and ammonium monooxygenase. Separate plate counts were conducted to determine the influence of nanoparticles on culturable soil bacteria and fungi. Soil treatments receiving ammonium sulfate displayed initial high levels of ammonium that nitrified by 89 h of incubation. Urea treatments characteristically displayed initial low, then increasing, and then decreasing levels of ammonium with corresponding increases in nitrate. The addition of either MgO or CuO nanoparticles did not alter the disappearance of ammonium or appearance of nitrate, indicating that neither urea hydrolysis nor nitrification was inhibited by the addition of the nanoparticles Approximately 50% of the added N was either immobilized in the soil microbial biomass or denitrified, regardless of the addition of either type of nanoparticle or source of N. Nanoparticle effects on culturable soil bacteria and fungi, and on gene expression will be discussed.