Formation and degradation kinetics of the biofumigant benzyl isothiocyanate in soil.
Glucosinolates (GSLs) are produced by plants of the Capparales order. Upon enzymatic hydrolysis the GSLs can be transformed to the toxic isothiocyanates (ITCs), which can be used as biofumigants for the control of soil-borne pests. The rates of ITC formation and degradation are critical to both biofumigation and the toxicity and leaching of GSLs and ITCs in soil. Degradation kinetics of benzyl GSL and benzyl ITC in a sandy and clayey surface and subsoil at 8-9 degrees C at natural moisture contents were investigated, as was the rate of formation of ITC from the GSL. Degradation of GSL followed logistic kinetics with t 1/2 = 0.7-9.1 days. Degradation was faster in clayey soil compared to sandy soil, and faster in surface soil compared to subsoil. In surface soils, up to 25% of added GSL was detected as ITC, while only 1-6% were detected in the subsoils. ITC degradation followed first-order kinetics with t 1/2 = 0.3-1.7 days, with faster degradation in subsoils than in surface soils. Based on the data for GSL hydrolysis and ITC degradation, the concentration of ITC following GSL application was successfully modeled assuming complete conversion of glucosinolate to isothiocyanate and first-order degradation of isothiocyanate.
Gimsing
Anne Louise
AL
Department of Natural Sciences, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark. angi@life.ku.dk
Poulsen
Jes Leisgaard
JL
Pedersen
Henrik Laurberg
HL
Hansen
Hans Christian Bruun
HC
D005651:Fumigation; D005961:Glucosinolates / Q000737:chemistry; D006868:Hydrolysis; D017879:Isothiocyanates / Q000737:chemistry*; D007700:Kinetics; D008956:Models, Chemical; D010575:Pesticides / Q000737:chemistry*; D012989:Soil Pollutants / Q000737:chemistry*
D005961:Glucosinolates; D017879:Isothiocyanates; D010575:Pesticides; D012989:Soil Pollutants; C031403:benzyl isothiocyanate