Development of hierarchical terron workflow based on gridded data – A case study in Denmark

Abstract Defining homogeneous zones by soil, climate, and landscape is a first step in creating terroir units. Applications in delineating homogeneous zones are commonly interested in all land use types (urban, forest, agriculture, etc.) or vegetation specific. Terron mapping is one method for creating non-vegetation homogeneous zones specifically for agricultural management and environmental assessment. Previously, terrons were defined as areas similar in soil and landscape. In this study, we implement climate as a key component in terron delineation and a workflow is developed that automates the necessary steps in generating and mapping terron classes. The workflow is flexible by allowing the user to define different input variables, method of modeling, output resolution, and hierarchical terrons. To assess the workflow, terron classes are modeled and mapped in Denmark: 1) using fuzzy c-means with various soil and climate gridded covariates to identify national regions, and 2) using k-means to develop regional terrons within the national regions based on soil and landscape gridded covariates. The elbow method was applied to determine the optimal number of national terron classes, dividing Denmark into three national regions. Each national region was further divided into nine regional terrons. The resulting regional terron map is comprised of 27 terrons. National and regional terrons are defined at 304 m and 30.4 m resolutions, respectively. A dendrogram produced from regional terron centroids was used to generalize terrons into groups of three to five terrons. From the generalization, seven groups are used to determine terrons that are most promising for crop production. The regional terron map constitutes a useful tool enabling future land-use management decisions and the development of terroirs for Danish crops.