Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/23/2004
Publication Date: 11/1/2004
Citation: Accinelli, C., Seebinger, J.D., Koskinen, W.C., Vicari, A., Sadowsky, M.J. 2004. Effects of incorporated corn residues on glyphosate sorption and mineralization in soil [CD-ROM]. In: ASA-CSSA-SSSA Proceedings. ASA-CSSA-SSSA Annual Meeting Abstracts, November 1-5, 2004, Seattle, WA.
Technical Abstract: In modern agricultural systems employing conservative tillage practices, glyphosate is widely used as a burndown herbicide in pre-planting of a wide range of crops. Considering that conservation tillage systems are characterized by a significant presence of crop residues at the soil surface, applied glyphosate is expected to encounter a soil matrix rich in poorly decomposed crop residues. In the present study, the influence of incorporation of different ratios of corn residues on mineralization and sorption of 14C-glyphosate was determined. Investigations were conducted under laboratory conditions using sandy loam and sandy soil samples and powered corn residues obtained from two corn hybrids: a stacked trait hybrid (Bt-protected and glufosinate-tolerant hybrid), and the corresponding non-transgenic isoline. Incorporation of corn residue in the range from 0.5 to 4% caused different effects on mineralization and sorption of 14C-glyphosate in the two soils. More specifically, low levels of incorporated corn residue did not affect or slightly stimulated herbicide mineralization in the sandy and sandy loam soils, respectively. In the latter soil, incorporation of the highest level of corn residues (4%) caused a significant decrease in 14C-glyphosate mineralization. 14C-glyphosate sorption on both soil types was significantly reduced in samples receiving high amounts of incorporated corn residues. Regardless of the added level, corn residues from the two isolines showed similar behavior in their effects on both mineralization and sorption of 14C-glyphosate in the sandy loam and in sandy soils.