Degradation of Ethephon in soil under aerobic conditions depended on the pH of the soil and the temperature, being more rapid at higher pH values and at higher temperatures. The DT50 values at 20 C ranged from 2.7 to 37.6 days The DT50 value at 10 C (for a Clay loam soil was slower (51.4 days) than the DT50 for the same soil at 20 C (22.2 days) In one study significant quantities of a volatile metabolite (ethylene) were found up to approximately 60% a.r. Furthermore, small levels of 2-hydroxyethanephosphonic acid (2-HEPA) were detected in the soil samples (< 10% a.r.) 2-HEPA is therefore regarded as a minor metabolite. The average DT50 value and average DT90 value was 19.2 and 101.6d respectively.