Remotely-sensed assessment of the impact of century-old biochar on chicory crop growth using high-resolution UAV-based imagery

anglais. peer reviewed

anglais. In recent years, special attention has been given to the long-term effects of biochar on the performance of agro-ecosystems owing to its potential for improving soil fertility, harvested crop yields, and aboveground biomassproduction. The present experiment was set up to identify the effects on soil-plant systems of biochar producedmore than 150 years ago in charcoal mound kiln sites in Wallonia (Belgium). Although the impacts of biochar onsoil-plant systems are being increasingly discussed, a detailed monitoring of the crop dynamics throughout thegrowing season has not yet been well addressed. At present there is considerable interest in applying remotesensing for crop growth monitoring in order to improve sustainable agricultural practices. However, studiesusing high-resolution remote sensing data to focus on century-old biochar effects are not yet available. For thefirst time, the impacts of century-old biochar on crop growth were investigated at canopy level using high-resolution airborne remote sensing data over a cultivatedfield. High-resolution RGB, multispectral and thermalsensors mounted on unmanned aerial vehicles (UAVs) were used to generate high frequency remote sensinginformation on the crop dynamics. UAVs wereflown over 11 century-old charcoal-enriched soil patches and theadjacent reference soils of a chicoryfield. We retrieved crucial crop parameters such as canopy cover, vegetationindices and crop water stress from the UAV imageries. In addition, our study also providesin-situmeasurementsof soil properties and crop traits. Both UAV-based RGB imagery andin-situmeasurements demonstrated that thepresence of century-old biochar significantly improved chicory canopy cover, with greater leaf lengths in biocharpatches. Weighted difference vegetation index imagery showed a negative influence of biochar presence on plantgreenness at the end of the growing season. Chicory crop stress was significantly increased by biochar presence,whereas the harvested crop yield was not affected. The main significant variations observed between referenceand century-old biochar patches usingin situmeasurements of crop traits concerned leaf length. Hence, theoutput from the present study will be of great interest to help developing climate-smart agriculture practicesallowing for adaptation and mitigation to climate.

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