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ARS Home » Plains Area » Brookings, South Dakota » Integrated Cropping Systems Research » Research » Publications at this Location » Publication #315715
Title: Maize, switchgrass, and ponderosa pine biochar added to soil increased herbicide sorption and decreased herbicide efficacy

Author
item CLAY, SHARON - South Dakota State University
item KRACK, KAITLYNN - South Dakota State University
item HANSEN, STEPHANIE - South Dakota State University
item Schneider, Sharon
item SCHUMACHER, THOMAS - South Dakota State University

Submitted to: Journal of Environmental Science and Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/14/2016
Publication Date: 5/6/2016
Citation: Clay, S.A., Krack, K., Hansen, S.A., Papiernik, S.K., Schumacher, T.E. 2016. Maize, switchgrass, and ponderosa pine biochar added to soil increased herbicide sorption and decreased herbicide efficacy. Journal of Environmental Science and Health, Part B. 51(8):497-507.

Interpretive Summary: Biochar is a by-product of pyrolysis conversion of plant material to biofuel. Biochars are being considered as soil amendments that may increase soil nutrients and water holding capacity. However, field application of biochar may produce unintended consequences to other crop management practices. We examined the impact of biochar application to the availability of the herbicides atrazine and 2,4-D in soil and how biochar affects the speed of plant germination. We used biochar produced from three materials, corn stover, switchgrass, and Ponderosa pine. Biochar-amended soils sorbed 5 to 10 times more herbicide than untreated soils, with only modest differences due to biochar type. Plants sensitive to these herbicides germinated more rapidly when biochar was present. These data indicate that even low levels of biochar addition to soil can increase herbicide retention by soil and reduce their potential effectiveness against weeds. Site-specific biochar applications may be needed to obtain maximal benefits without compromising other agronomic practices.

Technical Abstract: Biochars, a by-product of pyrolysis conversion of a wide array of plant biomass to biofuels, are being considered as soil amendments that may provide nutrients and increase soil water holding capacity. However, there may be unintended consequences to other crop management practices. We examined herbicide availability, by using batch equilibrium techniques, and herbicide efficacy using speed of germination tests. Radiolabeled atrazine and 2,4-D were added to biochar alone or to two soils that were amended with 1 and 10% biochar produced from three materials, maize (Zea mays) stover, switchgrass (Panicum vigatum), and Ponderosa pine (Pinus ponderosa) and allowed to equilibrate for 24 h. Biochar amended soils sorbed 5 to 10 times more herbicide than untreated soils, with only modest differences due to biochar type. Speed of germination of sensitive indicator species was monitored over a 10-d period in the presence or absence of biochars. Biochar presence increased the speed of seed germination compared with herbicide alone. These data indicate that even low levels of biochar addition to soil can increase herbicide sorption and reduce potential efficacy. Site-specific biochar applications may be warranted to obtain maximal benefits without compromising other agronomic practices.