Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Other
Publication Acceptance Date: 7/18/1996
Publication Date: N/A
Technical Abstract: Spatial variations of NO3-N, atrazine, and alachlor concentrations within the 0-15 cm soil profile of a Udollic Ochraqualf in north-central MO were studied in 1995. Soil samples from the 0-5, 5-10, and 10-15 cm soil depths were collected at 36 points within a 30-ha field 1, 4, and 8 weeks after chemical application. There was no spatial dependency among samples taken 1 1week after application. However, spatial dependencies were observed for th 4 and 8 week samples. Higher NO3-N, atrazine, and alachlor concentrations were found in areas of sediment deposition. Also, soil pH and CEC were found to significantly influence spatial variability. No influence of soil potassium, calcium, magnesium, and organic matter on spatial variability of the chemicals was found. Chemical concentrations in the 0-5 cm soil depth were appreciably higher than those concentrations in the 5-10 and 10-15 cm depths. Agrichemical losses to surface runoff during the study period were ealso measured. Atrazine and alachlor concentrations in runoff were > 35 pp for events that occurred during the first 2 weeks after application. For a runoff event that occurred 8 weeks after application, herbicide concentrations were < 2 ppb. NO3-N and NH4-N concentrations in runoff for all events were < 7 ppm for NO3-N and < 3 ppm for NH4-N.