Effectiveness of different mitigation measures to reduce runoff in sloping vineyards

Water flow regulation is particularly complex in hilly environments: the erosive and runoff flows that originate from cultivated areas may represent a potential risk for water resources, since runoff water may be responsible for transferring organic materials, nutrients and pesticides to superficial water bodies. Over the last twenty years, many mitigation measures to reduce runoff were proposed and tested: in particular, buffer strips can effectively contribute to surface water protection. In orchards and vineyards, permanent grass cover between rows may also contribute. Both measures allow for runoff flow containment, hindering water movement and facilitating the infiltration processes and adsorption phenomena. In order to test the effectiveness of these measures in a sloping environment, a 5 m grassed buffer strip placed at the bottom of the rows and grass cover between rows were compared to the traditional system of total weeding over three growing seasons in a sloping vineyard (gradient greater than 30%) in Aosta Valley. In the third year, the effect of soil compaction due to tractor traffic was also evaluated. Runoff flow volumes in the vineyard were measured. During the first two years of experimentation, no significant differences between the three treatments were found in terms of runoff volumes. In the third year, significant mitigation due to buffer strips and grass cover between rows was observed, but only when there was no tractor traffic, indicating that soil compaction may nullify the mitigation effects of buffer strips and grass cover.