Relationship between runoff and soil losses with rainfall characteristics and long-term soil management practices in a hilly vineyard (Piedmont, NW Italy)

Runoff and soil losses caused by natural rainfall events were monitored over a 10-year observation period in three experimental vineyard plots located in Alto Monferrato, a vine-growing area in Piedmont (NW Italy). The plots are characterized by a slope of about 15% and a soil classified as Typic Ustorthents, fine-loamy, mixed, calcareous, mesic. Each of them was managed with a different inter-row soil management practice: conventional tillage (CT), reduced tillage (RT) and controlled grass cover (GC), respectively. The rainfall characteristics, runoff discharge and concentration of soil in the water were measured. More than 150 rainfall events producing runoff and 63 erosive events were recorded. The data set was elaborated to investigate the relationships between runoff and soil losses with rainfall amount, duration and intensity, and to evaluate the effects of soil management methods. The amounts of water and soil that ran off the vineyard in the study period varied according to the season, rainfall characteristics and soil surface conditions. The highest soil losses were observed for tilled plots, with values of 111.5 and 207.7Mgha(-1) in the CT and RT plots, and only 25.6Mgha(-1) for GC treatment. The worst soil management practice was found to be the RT, whereas the GC was able to reduce soil lost from inter-rows in every season of the year, reaching the best effectiveness in summer (reduction greater than 90%). In addition, GC reduced runoff by 35% compared with the CT plot, showing a greater performance in summer and losing efficacy in autumn. A lower runoff reduction of 11% was observed in RT.