Influence of air velocity, air temperature, and air humidity on the volatilisation of trifluralin from soil

The volatilisation of the formulated herbicide trifluralin from soil surfaces was tested under defined conditions in a wind tunnel system. Seven experiments with different sets of climatic parameters were performed. The following air parameters were varied: velocity 0.4 m/s, 1.0 - 1.2 m/s, 1.8 m/s; temperature 15 degree Celsius, 20-21 degree Celsius; relative humidity 31 percent, 48-51 percent, 78 percent. The amount volatilised was quantified by analysing the trifluralin concentration in the air during four time intervals between 0 and 24 hours. The volatilisation rate for trifluralin ranged from 64 to 96 percent (initial dose 100 percent). The highest volatilisation was found for the experiment applying high air humidity conditions (20 degree Celsius; 1.2 m/s; 78 percent relative humidity). The lowest volatilisation was observed during the standard experiment with intermediate climatic conditions (21 degree Celsius; 1.0 m/s; 49 percent relative humidity).