The approximate movement and fate of 1,3-dichloropropene (Telone,^® D-D,^® or Vidden-D^®) and 1-2-dibromoethane (EDB) in two soils were predicted using extrapolations from laboratory experiments and soil-vapor phase concentrations obtained from simulated field experiments. The most far-reaching diffusion patterns in mineral soils are those obtained in soils whose moisture content is nearest the wilting point of plants (15 bars moisture tension). As the moisture content of the soil is increased, the diffusion pattern gradually becomes more limited. This effect is most striking when fine-textured soils have moisture contents in excess of ½ bar moisture tension (at the 30.5 em depth).

Fumigation of warm soils (25°C) results in a faster rate and greater distance of nematicide diffusion. In colder soils (5°C), the rate of diffusion is slower, and the persistence of the chemical is longer, but the total distance of diffusion of an effective dosage is decreased. Increased soil temperatures result in increased rates of hydrolysis of cis- and trans-1,3-D. The same is not true of EDB.

The soil texture and type determine to a large extent the amount of soil moisture present and the size of the connecting air spaces. Soil-air space and size of pores are important, because these chemicals move primarily in the vapor phase and the smaller pores are most easily blocked when water is present. It is important that fumigant applicators are successful in sealing the soil surface and chisel shank hole after an application. Failure to do this results in significant losses to the atmosphere especially, if the subsoil is in a moist to wet condition.