Evaluation of Sorption Coefficients for Pyroxasulfone, -Metolachlor, and Dimethenamid-

Sorption coefficients were evaluated for pyroxasulfone, s -metolachlor, and dimethenamid- p across 25 soil types with different chemical and physical properties to better understand how soil properties influence the binding of pyroxasulfone in different soils. Sorption coefficients were determined using a batch equilibrium method to evaluate relative differences in binding among the three herbicides. Based on water solubility values, we would have expected the relative order of binding to be dimethenamid- p (1450 mg L −1 at 20°C), s -metolachlor (530 mg L −1 at 20°C), and pyroxasulfone (3.49 mg L −1 at 20°C) in order of increasing binding. However, when sorption coefficients were calculated, we observed the order of pyroxasulfone = dimethenamid- p < s -metolachlor in the order of increasing binding. The average K d (sorption coefficient) values were 1.7, 2.3, and 4.0 L kg −1 for pyroxasulfone, dimethenamid- p , and s -metolachlor, respectively. Although dimethenamid- p has water solubility values that are over 400 times greater than pyroxasulfone, there was no statistical difference in binding between pyroxasulfone and dimethenamid- p. s -Metolachlor binding was statistically greater than both pyroxasulfone and dimethenamid- p. Across all soil chemical and physical properties, sorption coefficients for all three herbicides were highly and statistically correlated to soil organic matter. Sand and silt were also statistically correlated to binding, although these correlations could be explained by the high correlation of organic matter to these properties. Evaluation of sorption coefficients indicates that pyroxasulfone is most prevalent in the soil solution where herbicides are available for plant uptake. Reduced soil binding and greater activity at the target site could contribute to comparable weed control efficacies of pyroxasulfone even when applied at lower use rates compared to either s -metolachlor or dimethenamid- p

\u3ci\u3eAgronomy Journal\u3c/i\u3e Turns One Hundred

During 2008 we celebrate the centennial anniversary of Agronomy Journal. Many people have certainly been influenced in some way by the science published during the 100-yr existence of the journal. From Volume 1 up through Volume 98 (2006) there have been more than 30,290 authors who published 15,232 articles totaling 89,056 pages. More than 2545 editors were required to review and edit the papers published in Agronomy Journal, in addition to the manuscripts submitted but not published. As a current snapshot of Agronomy Journal, we published 60% of the manuscripts submitted in 2005. In both 2003 and 2004, we accepted 55% of the manuscripts submitted. In a comparison of 48 peer journals in 2005, the impact factor of Agronomy journal ranked 12th at 1.473 and the total citations for the journal ranked fourth at 6723. Commentaries on the early history of Agronomy Journal have been previously published. In our article, we focus on the journal’s history during the past 25 yr. We fully expect that the future of Agronomy Journal will be even more exciting, rewarding, challenging, and valued as the past 100 yr. We eagerly look forward to the next 100 yr of Agronomy Journal