Does green manure improve soil quality in a dry vineyard of Lake Garda?

Climate change and rainfall reduction have a negative effect on soil quality, that is the capability of maintaining biological productivity, environmental quality and promoting animal and plant health. Therefore, seeking solutions able to mitigate these effects is essential. This study, carried out in a dry vineyard in the Lake Garda area, is part of a project funded by GAL GARDAVALSABBIA2020 and analyses the effect of green manure on soil quality, assessed by chemical (nutrient availability) and biological (soil biological activity and biodiversity of microarthropod community) indicators. The vineyard was divided into three plots: CI (control with permanent grass), M1 (green manure mix enriched with legumes) and M2 (balanced green manure mix). After a year, green manure, even before mulching, contributed to sequester and gradually release nutrients during vine growing season, especially in M2. This was highlighted by the higher available concentrations of Mg, P and N in M2 than in the others. Additionally, legumes contributed to enrich of nitrogen the soil of plots with green manure, thanks to the nitrogen fixation by the symbiont bacteria. Biological activity measured as dynamic of soil respiration was greater in plots with green manure, although undergoing the combined effect of temperature and humidity. The microarthropod biodiversity indices showed higher values in autumn than in summer, being affected by seasonality; however, autumn increase was significant only in M1 and M2. These preliminary results show how green manure contributes to improving soil quality already after only one year of study, mitigating the negative effects of aridity.