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F* '~S- '''-, 4ttJ ~j MONITORING RESULTS From 1994 to 1995, samples of irrigation water in the furrows were taken to check for Oxyflourfen found in Goal and for Bromoxynil found in Buctril. Two sites on onions used for sampling were a conventional irrigation site using siphon tubes and a surge irrigation site using Polyacry- lamides (PAM). According to the Colorado State Pesticide Data Base, Buctril and Goal have a soil half life of seven days. The absorbed runoff loss poten- tial of the chemicals is medium; the solution runoff loss potential is small; and the leaching potential is small. All samples were taken at least two weeks and two irrigations after the last ap- plication of the herbicides. On the conventionally irrigated onions there was an increase in Oxyfluorfen and Bro- moxynil concentrations from midpoint in the field to the end. This increase was an indication that the non-mobile chemicals were adhering to the soil particles. As furrow erosion occurred these. chemical concentrations increased as the soil~ediment moved down the field and concen- trated~in lb:wer areas. . ; . ustdg surgefri$~'!' ti;p~)fi1~ PAM' no con- centratiort incte~s~~ . ~. rl.~gtt~lf~.tlsin-~ ~~- vanced irrigation tecH i~~r~di'lJJrt?t'J1).o~etl1e% soil in the field or carry it ofrwifh ~~CtSsit~it~l;:j!~'..,;,: water. Therefore, using. surgeirrigal:ibri::hvJ~:n;~:~;L , ----?y:~}:_ "-_~{'i->i,_--:)w{} - PAM left the chemical additives .where theYl5;~~:i?S:. '.; _'NF;';,'~f>' longed. ... .- It needs to be noted that there are not standards for concentrations of Oxyflourfen a:rt,d Bromoxynil. The increased concentrations de- tected are in parts per million. But the process clearly shows what poor irrigation techniques do to the soil and chemicals applied to it.