Developing a methodology for the determination of homogeneous soil zones within long-term agroforestry experimental sites

Abstract

On the one hand, the demand for locally produced nuts is increasing in Flanders while on the other hand there is a growing interest in agroforestry to help mitigate the environmental problems caused by conventional agriculture. In this context, a project coordinated by ILVO aims to develop agroforestry with walnut trees in Flanders and in the Netherlands. Part of their research focuses on late-budding varieties in order to delay competition for light with the crop and to avoid late frost damage. Seven long-term experimental trials on late-budding walnut trees were launched in 2021. The purpose of the present study was to identify zones with relatively homogeneous soil properties in four of the sites thanks to soil electromagnetic induction scan data clustering and soil analyses. The second objective was to analyse the impact of this zones on the performance of the walnut trees. Moreover, the methodology applied to this specific trial is intended to be applicable to other contexts. In each site, at least one zone with significant differences in terms of soil texture, water table level or water content has been identified. Although the current results are not conclusive as to the impact of these zones, differences in performance in some of them can be expected in the next few years, as the trees are still too young to draw any conclusions at this time. Finally, this method appears to have value in a broader context and can be applied to other agroforestry trials. Criticisms can however be made about the soil sampling method.