Organic matter effects on phase partition of 1,3-dichloropropene in soil.

The fumigant 1,3-dichloropropene (1,3-D), in combination with chloropicrin, is considered a major replacement to methyl bromide (MeBr). This study was conducted to better understand phase partitioning of 1,3-D and the role of organic matter in its adsorption to soil. Partition of 1,3-D between air and water (K(H)), and between soil and water (K(f)), was determined by quantifying the concentration in both phases upon equilibrium. At 20 degrees C, the K(H) values of (Z)- and (E)-1,3-D were 0.052 and 0.033, respectively. In four California and Florida soils, the K(f) values of 1,3-D isomers ranged from 0.39 to 8.55, and the K(oc) values ranged from 18 to 60. The relatively high K(H) and low K(f) imply that 1,3-D is highly mobile in most soils after subsurface application. Adsorption of 1,3-D in native soils and soils amended with manure compost increased with increasing soil organic matter content. This suggests that organic wastes may be applied to soil to increase 1,3-D adsorption, thus reducing its potential for offsite movement.