Response of Biochemical Properties in Agricultural Soils Polluted with 4-Chloro-2-methylphenoxyacetic Acid (MCPA) under Severe Drought Conditions

The soil moisture content can vary the behavior of biochemical activity and its incidence on herbicides. The objective of this manuscript was to assess, under controlled laboratory conditions, whether a prolonged 75-day drought can affect the behavior of 4-chloro-2-methylphenoxyacetic acid (MCPA) herbicide and biochemical properties in three agricultural soils (Typic Xerofluvent, SA, Typic Haploxeralf, SB, and Vertic Chromoxert, SC). During the 75 experimental days, two irrigation levels were maintained: (1) watered soils during this experimental period, and (2) non-watered soils, where no water was supplied during the experimental period. The evolution of the herbicide and the biochemical properties were different depending on the soil moisture status. In the SA, the biochemical properties decreased until day 35 after initiating the experiment, whereas in the SB and SC, the biochemical parameters decreased until days 25 and 45, respectively. The application of herbicide to the non-watered soil increased the inhibition of biochemical properties. In non-watered SA, MCPA degradation occurred at day 45 after initiating the experiment, whereas in SB and SC, MCPA degradation occurred at days 35 and 60 after starting the incubation process, respectively. These results suggest that the soil persistence of MCPA under drought conditions increases, and consequently increases soil contamination