Dissipation and Phytotoxicity of Sodium Azide in Soil

The dissipation of sodium azide (NaN3) from soil was significantly affected by pH, soil moisture, and relative humidity (RH). Loss was more rapid from acid than from alkaline soils. Moist soil (20 to 60% field capacity) or air dry soil in a moist environment (100% RH) lost NaN3more rapidly than air dry soil in a dry (0% RH) environment. However, dissipation was decreased when soil moisture exceeded 60% field capacity. Degree of leaching and phytotoxicity of NaN3was not affected by soil pH. Bioassay studies indicated that 10 ppm NaN3in the soil significantly reduced germination and growth in plant species tested. At concentrations of NaN3below 10 ppm, plant germination was often delayed but normal growth occurred after NaN3dissipation.