Effect of soil temperature and moisture on degradation of the oxyfluorfen herbicide

We have studied the combined effect of temperature and moisture on a soil contaminated with the oxyfluorfen herbicide at a dose of 4 l ha−1 in terms of the biochemical activity (dehydrogenase activity and ergosterol content) of said soil, as well as on the concentration of said herbicide over a 90-day period in a laboratory setting. Two degrees of moisture were used: (1) irrigated soils maintained at 60% of their water retention capacity and (2) non-irrigated soils (non-watered soils, without irrigation). These treatments were subjected to three temperatures (4 °C, 25 °C, and 40 °C, respectively). In all cases, the oxyfluorfen caused a toxic effect on both the dehydrogenase activity and ergosterol content of the soil. However, this toxic effect was greater in non-watered soils, possibly due to the combined effect of the herbicide toxicity and the soil drought conditions. With regard to temperature, the results indicate that dehydrogenase activity and ergosterol content in soil were more negatively affected when samples were incubated at higher temperatures (40 °C). Statistical analysis suggests that temperature may have a greater specific weight or influence than soil moisture, since a variation in temperature causes a variation in soil moisture.