Herbicide Loading to Shallow Ground Water beneath Nebraska's Management Systems Evaluation Area (original) (raw)

2003, Journal of Environment Quality

Atrazine is the most widely detected pesticide in the nation's ground water and the USEPA has set 3 g L Ϫ1 Better management practices can counter deterioration of ground as the maximum contaminant level (MCL) in drinkwater quality. From 1991 through 1996 the influence of improved irrigation practices on ground water pesticide contamination was assessed ing water. at the Nebraska Management Systems Evaluation Area. Three 13.4-ha Generally, nonpoint-source loading of pesticides in corn (Zea mays L.) fields were studied: a conventional furrow-irrigated shallow ground water beneath agricultural fields is visufield, a surge-irrigated field and a center pivot-irrigated field, and a alized as a complex, nonuniform network of macropores center pivot-irrigated alfalfa (Medicago sativa L.) field. The corn fields conveying contaminants through the vadose zone to the received one identical banded application of Bicep (atrazine [6-chlorowater table where high input concentrations are par- -diamine] ϩ metolachlor tially masked by vertical and radial dilution. The major- ity of loading has been attributed to the transfer, mixing, acetamide]) annually; the alfalfa field was untreated. Ground water application, and disposal or "routine use" of pesticides samples were collected three times annually from 16 depths of 31 multiin agriculture. Hallberg (1989), however, points out that level samplers. Six years of sample data indicated that a greater than 50% reduction in irrigation water on the corn management fields low-