Ethylene Adsorption and Movement in Soils and Adsorption by Soil Constituents

Adsorption of ethylene in four North Carolina soils and on montmorillonite, kaolinite, and organic matter was studied. Rate of ethylene diffusion through soils in the field and laboratory and its rate of loss from field soil were also examined. Ethylene was adsorbed in greater quantities on two soils which were limed as compared to their field pH. Ethylene adsorption by another surface soil and a subsoil were unaffected by pH changes. The order of adsorption of several hydrocarbon gases by two of the soils was ethylene = propylene ≫ methane ≥ ethane ≥ propane. Montmorillonite adsorbed more ethylene than did kaolinite or organic matter. Soils which adsorbed ethylene also had slower diffusion rates when ethylene was injected into a homogeneous soil column. Ethylene diffused 2.1 m horizontally and 0.7 m vertically to cause at least 50% witch weed ( Striga lutea Lour.) seed germination in a Lakeland soil in the field. Witchweed seed germination as high as 90% was obtained at soil depths of 0.3 m and horizontal distances of 0.7 m from the point of ethylene injection.