title: Biochar Soil Additions Affect Herbicide Fate: Importance of Application Timing and Feedstock Species.
abstract: 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 efficacy of two herbicides, clomazone (CMZ) and bispyribac sodium (BYP). To this aim, we evaluated CMZ and BYP sorption, persistence, and leaching in biochar-amended soil. Sorption of CMZ and BYP was greater in soil amended with BC produced at high temperature (700 °C). Significant sorption of the neutral CMZ herbicide also occurred in amended soil with BC prepared at low temperature (350 and 500 °C). For both herbicides, desorption possessed higher hysteretic behavior in soil amended with BC made at 700 °C (pyrolysis temperature). 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 700 °C was added to soil. All BCs suppressed the leaching of CMZ and BYP as compared to the unamended soil. Amendment with 700 °C BC inhibited the action of CMZ against weeds, but 350 and 500 °C BCs had no such effect when added to soil. BYP activity was similar to that exhibited by unamended soil after the addition of 700 °C BC. From these results, biochar amendments can be a successful strategy to reduce the environmental impact of CMZ and BYP in soil. However, the phytotoxicity of soil-applied herbicides will depend on BC sorption characteristics and the pesticide's chemical properties, as well as the pesticide application timing (e.g., pre- or postemergence). According to our results, proper biochar screening with intended pesticides in light of the application mode (pre- or postemergence) is required prior to use to ensure adequate efficacy.
authors.affiliation: Instituto de Recursos Naturales y Agrobiologı́a de Sevilla (IRNAS), CSIC , Avenida Reina Mercedes 10, 41012 Sevilla, Spain.
authors.forename: Beatriz
authors.identifier: http://orcid.org/0000-0002-7244-778X
authors.initials: B
authors.lastname: Gámiz
authors.affiliation: Instituto de Recursos Naturales y Agrobiologı́a de Sevilla (IRNAS), CSIC , Avenida Reina Mercedes 10, 41012 Sevilla, Spain.
authors.forename: Pilar
authors.initials: P
authors.lastname: Velarde
authors.affiliation: Agricultural Research Service, U.S. Department of Agriculture , 439 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, Minnesota 55108, United States.
authors.forename: Kurt A
authors.initials: KA
authors.lastname: Spokas
authors.affiliation: Instituto de Recursos Naturales y Agrobiologı́a de Sevilla (IRNAS), CSIC , Avenida Reina Mercedes 10, 41012 Sevilla, Spain.
authors.forename: M Carmen
authors.initials: MC
authors.lastname: Hermosín
authors.affiliation: Instituto de Recursos Naturales y Agrobiologı́a de Sevilla (IRNAS), CSIC , Avenida Reina Mercedes 10, 41012 Sevilla, Spain.
authors.forename: Lucía
authors.initials: L
authors.lastname: Cox
mesh_terms: D000327:Adsorption; D001565:Benzoates / Q000737:chemistry*; D002606:Charcoal / Q000737:chemistry*; D006540:Herbicides / Q000737:chemistry*; D007555:Isoxazoles / Q000737:chemistry*; D023303:Oxazolidinones / Q000737:chemistry*; D011743:Pyrimidines / Q000737:chemistry*; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors
chemical_list: D001565:Benzoates; D006540:Herbicides; D007555:Isoxazoles; D023303:Oxazolidinones; D011743:Pyrimidines; D012987:Soil; D012989:Soil Pollutants; C540010:biochar; D002606:Charcoal; C095255:clomazone; C549011:bispyribac
keywords: bispyribac sodium; clomazone; degradation; efficacy; leaching; soil amendments; sorption; weed control