Diversifying grapevines with aromatic plants changes the soil habitat, microbial community composition and functions toward more efficient substrate use and nutrient allocation

Crop diversification is increasingly recognized to enhance agricultural sustainability, but the interplay of plants, soil, and soil microbiome is not yet fully understood. In a 3-yr field study, we investigated the effects of diversification in the plant row under grapevines (Vitis vinifera) with aromatic plants, i.e. Origanum vulgare (GDO) or Thymus vulgaris (GDT) on the soil habitat with its chemical and microbiological properties, while grapevines alone with mechanical tillage served as a control (GMC). We assessed microbial biomass, respiration, DNA-based prokaryotic and fungal community composition, enzyme activity, and potential nitrification together with soil properties such as soil and particulate organic matter (SOM, POM), nutrient status, pH, and soil water content in the topsoil horizon (0 – 10 cm) of an organically farmed, steep-sloped vineyard.