Gamma-ray spectrometry In Burgundy vineyard for high resolution soil mapping

Aim: A soil mapping methodology based on gamma-ray spectrometry and soil sampling has been applied for the first time in Burgundy. The purpose of this innovative high-resolution mapping is to delimit soil areas, to define elementary units of soil for terroir characterization and vineyard management. The added value of this integrated approach is a continuous geophysical mapping of the soil with an investigation depth of 60cm.

Methods and Results: The principle of the gamma-ray spectrometry is a record, by a crystal of Cesium Iodide, of the natural radiation produced in soils (U, K, Th, Cs). The interpretation required the calibration of the natural gamma ray using soil samples description and analysis. The agricultural practices feedback of the winegrower is also fundamental for the interpretation.

Our soil mapping approach depends on the surface of the study area. For a parcel, the sensor is carried on a man’s back. For an entire vineyard, the sensor is fixed on a drone. This low elevation does not impact significantly on the intensity of the signal.

Conclusions:

We have investigated 18 parcels of the Domaine de la Tour Bajole (Saint Maurice-les-Couches), Domaine de la Chapelle (Pouilly-Fuissé), Domaine du Mas des Tines and Sources d’Agapé (Saint-Amour). These parcels are representative of the soil diversity of this region: soils issues from granites, granitic arena, Triassic clays and sandstones, Jurassic marls and limestones and deep argillaceous soils. The gamma-ray signal analysis allowed to discriminate and map these seven soil types, as well as colluvium and anthropic features.

Significance Impact of the Study: The application of gamma-ray spectrometry for vineyard soil characterization has been initiated in South Africa by Mlwilo (2010) (sensor fixed on an all-terrain vehicle, to investigate soils issued from shale, granitic arena and metamorphic rocks). Our study is the first use of gamma-ray spectrometry for vineyard mapping in France. It confirms the relevance of this integrated method for improving the resolution of soil mapping. The resolution is metric, and this tool separates elementary soil units at the scale of the sub-parcel (“sub-climat”). Today, the miniaturization of sensors and the carrying capacity of drones allows quick gamma-ray spectrometry to capture new high-resolution soil heterogeneity mapping on large areas.