ARS | Publication request: SPATIAL VARIABILITY OF HERBICIDE SORPTION ON SOIL

Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: September 15, 2000
Publication Date: N/A

Technical Abstract: A limitation in using sorption coefficients to predict herbicide transport is the spatial variability of soil properties over large fields. Spatial variability in alachlor and imazethapyr sorption was determined on samples from a 31.4-ha field; pH 4.9-7.6, 1.45-5.80 percent OC, and 26-65 percent clay. Alachlor sorption Kd ranged from 5.45 to 21.5. OC content was the most important property influencing sorption. Imazethapyr Kd varied from 0.18 to 3.78, but showed two distinct patterns in spatial distribution; areas with pH greater than 6.25 where Kd variation was based on pH; and areas with pH less than 6.25, where Kd variation was also affected by OC. Based on spatial variability of soil properties and sorption, the field could be divided into management areas for site-specific herbicide application to reduce potential off-site transport. However, field-scale spatial patterns in sorption can vary with the method of interpolation. We ecompare geostatistical and linear sorption model based regression methods.