estimate of trifluralin half-life in soil by bioassay experiment

this study was conducted to investigate the effect of organic and bio-fertilizers on trifluralin durability.herbicide persistence is an important consideration in crop production since residue levels of trifluralin herbicides can persist to the next growing season and may injure sensitive crops in the rotation. residues of trifluralin persist in the soil for long periods. extremely small amounts of resides can be devastating to some crops that are planted in the following year. bioassay experirent is a common and cheaper experiment for herbicide residue detection in soil.in order to estimation of trifluraline halfe life in soila field experiment conducted as a factorial arrangement in completely randomized block designwith 3 replications. experimental factor included two levels of trifluraline (ec %48) application rate480 and 960 g.ha-1 a.i.). for determination of trifluralin residue, soil sampling was taken from 0 to 10 cm soil dept at 0, 3, 7, 15, 30, 60, 90 and 120 days after spraying. soil sampling and soil treatments were transferred to the greenhouse. the results of bioassay experiment with sorghum plants showed decreasing trifluralin durability with the application of organic and biological fertilizer. the highest half life were observed (144 and 130 days), by using 480 g. a.i/ha related to shoot and root biomass and no fertilizer application respectively and the least a half-life was in shoot biomass related to organic fertilizer treatment (18 and 19 days) and 480 and 960 g trifluralin active ingredient.