Soil management of interrow spacing as an important factor to protect the vineyard soils from runoff and erosion under the Mediterranean climate

Nearly one third of the Herault vineyard (south of France) is planted on soils very sensitive to water runoff and erosion. This sensitivity is reinforced by the Mediterranean rain regime, characterized by sudden and violent rainfalls during autumn and spring, by the slopes of the plots, the bare surface of the inter-row spacing and the poor organic matter content of the upper part of these soils. The effects on the vine landscapes and production can be noticeable.
The soil management is one of the more influent parameters on the risk of runoff and erosion. By now, most of the vineyard soils are maintained bare all the year round by either soil tillage or chemical weeding.
A 7-years experiment (2000-2006) was set up on a 1 ha surface plot to compare the effects of soil management on runoff, soil erosion and agronomic results. It aimed to compare chemical weedings (antisprouting or defoliating herbicides), soil tillage and permanent grass covering 50% of the surface. Results show that permanent grass cover reduces runoff by nearly 50 % compared to chemical weeding, thanks to a better infiltrability. This leads to a significant decrease of erosion with a cover grass (1.4 T/ha/y) compared to chemical weeding (8.5 T/ha/y).
There were few effects on the production : the grass cover induces less yield (-16%) and less growth (-27% in weight) compared to the rest of the plot.
The soil was little affected by the cultural practices. The main result is that the grass cover made the soil microbiology live again, with an increase of 48% of the total microbial biomass.
The results of this experiment are significant enough to give advice on the best way to manage the vine according to the plot characteristics, to avoid runoff and erosion.