|GAMIZ, BEATRIZ - Collaborator|
|VELARDEA, PILAR - Collaborator|
|HERMOSIN, M. CARMEN - Collaborator|
|COX, LUCIA - Collaborator|
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/29/2017
Publication Date: 3/29/2017
Citation: Gamiz, B., Velardea, P., Spokas, K.A., Hermosin, M., Cox, L. 2017. Biochar soil additions impacts herbicide fate: Importance of application timing and feedstock species. Journal of Agricultural and Food Chemistry. 65(15):3109-3117. Available: http://pubs.acs.org/doi/abs/10.1021/acs.jafc.7b00458.
Interpretive Summary: The environmental risk of soil applied agrochemicals is often assessed through sorption experiments to guide field management decisions. However, very little attention has been focused on the different timings possible for herbicide (pre- or post- emergence) and the impact of biochar on these different modes of action. These data show that different soil amendments could impact the length of time that the chemicals stay active in the protection against weeds. The data suggests that biochar additions reduce the time window that the herbicide is effective, which is particularly important for pre-emergence applications of herbicides or chemicals with residual action in the soil. These results are significant to farmers and policy makers and will assist scientists and engineers in developing improved guidance for application timing of herbicides to biochar amended soils.
Technical Abstract: BACKGROUND: Biochar (BC), solid biomass subjected to pyrolysis, can alter the fate of pesticides in soil. We investigated the effect of soil amendment with several biochars on the sorption, persistence, leaching and bioefficacy of the herbicides clomazone (CMZ) and bispyribac sodium (BYP). RESULTS: Sorption of CMZ and BYP was greater in soil amended with BC produced at high temperature (700ºC). Noticeable sorption of CMZ also occurred in amended soil with BC prepared at low temperature (350 and 500º). For both herbicides, desorption was more hysteretic in soil amended with BC made at the highest temperature of pyrolysis. Dissipation of CMZ was enhanced after addition of BCs to soil, but no correlation between persistence and sorption was observed. Persistence of BYP was up to 3 times greater when BC made at 700ºC were added to soil. All BCs suppressed the leaching of CMZ and BYP as compared to unamended soil. Amendment with 700C BC inhibited the action of CMZ against weeds, whereas BYP phytotoxicity was similar than that exhibited by unamended soil. CONCLUSIONS: Biochar additions can be a successful strategy to reduce leaching and degradation losses of CMZ and BYP in soil, reducing their environmental impact. On the other hand, biochar additions also reduce their efficacy depending on BC´s characteristics as well as application mode (pre- or post-emergence).