|TRIGO, CARMEN - University Of Minnesota|
|COX, LUCIA - University Of Minnesota|
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/22/2014
Publication Date: 10/22/2014
Publication URL: https://handle.nal.usda.gov/10113/60459
Citation: Trigo, C., Spokas, K.A., Cox, L., Koskinen, W.C. 2014. Influence of soil biochar aging on sorption of the herbicides MCPA, nicosulfuron, terbuthylazine, indaziflam, and fluoroethyldiaminotriazine. Journal of Agricultural and Food Chemistry. 62:10855-10860.
Interpretive Summary: Biochar has been gaining attention, both in the public and scientific circles, as a means to combat climate change and at the same time improve soil fertility. However, there has been very little attention focused on the impact of weathered biochar on herbicide sorption. In this research, we looked at the effect that weathering in the field had on 5 different herbicides Our results support the conclusion that the properties of the biochars change with soil exposure. Thereby, this research highlights that biochar properties need to be selected based on the desired mode of action, but this might not be a static property since the chemistry of biohcar changes with time. Additional research is needed to fully characterize the surface chemistry responsible for these effects. These results are significant to farmers and policy makers and will assist scientists and engineers in developing improved biochars based on properties to minimize agrochemical transport and improve soil carbon management.
Technical Abstract: Sorption of four herbicides and a metabolite of indaziflam on a fresh macadamia nut biochar and biochars aged one or two years in soil was characterized. On fresh biochar, the sorption was terbuthylazine (Kd = 595) > indaziflam (Kd = 162) > MCPA (Kd = 7.5) > fluoroethyldiaminotriazine (Kd = 0.26) and nicosulfuron (Kd = 0). Biochar surface area increased with aging attributed to the loss of a surface film. This was also manifested in a decline in water extractable organic carbon with aging. Correspondingly, an increase in the aromaticity was observed. The higher surface area and porosity in aged biochar increased sorption of indaziflam (KdBC-2yr = 237) and fluoroethyldiaminotriazine (KdBC-1yr = 1.2 and KdBC-2yr = 3.0), but interestingly decreased sorption of terbuthylazine (KdBC-1yr = 312 and KdBC-2yr = 221) and MCPA (KdBC-1yr = 2 and KdBC-2yr = 2). These results will facilitate development of biochars for specific remediation purposes.