Spatial variability of imazethapyr sorption in soil

• Published in: Weed science 1999-04, Vol.47 (2), p.243-248
• Main Authors: Oliveira, Rubem S., Koskinen, William C., Ferreira, Francisco A., Khakural, Bhairav R., Mulla, David J., Robert, Pierre J.
• Format: Article
• Language: English
• Subjects: Acid soils; Agricultural soils; Agrology; Desorption; Herbicides; Organic soils; Pesticides; Soil water; Soil, Air, and Water; Sorption; Spatial variability
• ISSN: 0043-1745; 1550-2759
• DOI: 10.1017/S0043174500091670

A significant limitation in using sorption coefficients (Kd ) to predict solute transport through natural soils is the spatial variability of soil properties over large field areas. Spatial variability in Kd for imazethapyr was determined on representative samples from a 31.4-ha field, covering a pH range from 4.9 to 7.6 and an organic carbon (OC) range from 1.45 to 5.80 g kg−-1. Kd varied from 0.18 to 3.78 across the field, with an average value of 1.56. The analysis of Kd variability showed two distinct patterns in spatial distribution: areas in which pH > 6.25 and Kd < 1.5, where Kd variation is based primarily on pH, and areas in which pH < 6.25 and Kd > 1.5, where other soil properties, i.e., OC content, have a significant influence on Kd variation. Based on soil pH distribution, an easily measured property, the field was divided into two potential management areas. This separation allowed identification of portions of the field where herbicide sorption would be minimal, with a relatively higher potential for leaching (i.e., areas with Kd < 1.5), and provided a rationale for site-specific imazethapyr application.