Ethylene Inhibition of Ammonium Oxidation in Soil
- Lynn K. Porter *
Small quantities of ethylene (C2H4) are produced by bacteria and fungi in soils. Ethylene is produced when nitrogenase activity is measured by acetylene (C2H2) reduction. Acetylene has been used as a nitrification inhibitor and has been shown to produce C2H4 in flooded rice soils. Whether C2H4 affects the oxidation of NH4 by the soil's nitrifying organisms and at what concentrations was the focus of this study. A Weld clay loam surface soil (fine, montmorillonitic, mesic Aridic Paleustoll) was treated with (NH4)2SO4, subjected to various partial pressures of C2H4 and incubated at 30 °C. At designated incubation times, the atmospheres of the incubation flasks were analyzed for O2, CO2, and C2H4 by gas chromatography (GC) and the soil was analyzed for NH4, and NO3 plus NO2 by steam-distillation procedures. At a C2H4 partial pressure of 0.017 kPa, NH4 oxidation was similar to untreated samples. At a C2H4 partial pressure of 0.17 kPa, NH4 oxidation was partially inhibited and, at a C2H4 partial pressure of 4.55 kPa, inhibition was nearly complete.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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