Submitted to: American Chemical Society National Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 12, 2011
Publication Date: August 28, 2011
Citation: White Jr, P.M., Potter, T.L., Lima, I.M. 2011. Sugarcane bagasse and pine wood biochar effects on aerobic soil dissipation of metribuzin and pendimethalin. American Chemical Society Fall 2011 National Meeting and Exposition, August 28 - September 2, 2011, Denver, Colorodo. CDROM. Technical Abstract: There is considerable interest in biochar use as an agricultural soil amendment. Available data indicate that there is potential for both positive and negative impact. On the positive side are increased organic matter, increased herbicide persistence, and improved soil physical properties. Negative impacts may include herbicide carryover and reduced efficacy, increased availability for runoff, and lower crop nutrient availability. Our work focused on impacts on soil dissipation rates of metribuzin and pendimethalin, two common soil-residual herbicides with different sorption characteristics. Biochars produced by pyrolysis of sugarcane bagasse (350°C and 700°C ignition temperature) and pine wood (400°C ignition temperature) were mixed with three soils, a silty-clay loam with 0.9% organic carbon; a clay with 1.2% carbon and a sandy loam with 0.8% carbon). Biochar addition increased the soil carbon content by a factor of at least 2. Metribuzin and pendimethalin were added to all soils with and without biochar. Soils were sequentially extracted using methanol after 0, 7, 14, 21, 28, 42, 63, 86, and 111 days incubation at constant temperature and water content. The parent compounds and degradates were analyzed in extracts by HPLC using atmospheric pressure chemical ionization mass spectroscopy. Dissipation data and degradate formation will be discussed, as well as the effect of the biochars on herbicide dissipation.