Effect of agricultural practices on volatile organic compound (VOC) emissions from winter wheat
Résumé
Despite the important land cover of crops, biogenic volatile organic compounds (BVOCs) emissions from agricultural areas remain poorly characterized, especially from field experiments. There is even less knowledge about the effect of agricultural practices (fertilization, pesticide spreading, etc.) on these emissions. The global aim of the present study is to reinforce our knowledge on BVOC emissions from agricultural crops. A field campaign was carried out at a measurement station located at Grignon ICOS site(France), 40 km southwest from Paris. The goal of the study was i) to quantify BVOC fluxes over a wheat stand and ii) to evaluate the effect of agricultural practices (manure and pesticide spreading) on these emissions. The experimental set-up consisted in measuring eddy covariance fluxes of momentum, latent and sensible heat, CO2 and BVOCs (with a PTR-Qi-TOF-MS - national instrument within the ANAEE-France framework). Results show that methanol was the most emitted BVOC, in agreement with few reported studies about wheat. Immediately after manure spreading, an increase of emissions of several compounds was observed. Especially, m/z 109.06 (C7H8O), which was previously characterized as strongly emitted by liquid manure, was observed in the field. We also report the first online measurement of pesticide with a PTR-Qi-TOF-MS. The spread fungicide Chlorothalonil was surprisingly still detected in the gas phase 21 days after spreading. Our results provide new insights in BVOC emissions from crops and the effect of pesticide and manure spreading on these emissions.