Effect of soil management systems on erosion and nutrition loss in vineyards on steep slopes.

Green cover in vineyards on steep slopes may play an important role in the reduction of soil erosion. The main objective of this study was to investigate the effect of a permanent green cover (PGC) on soil erosion, together with any loss of nutrients, and to compare it with periodic soil tillage (PST). PST took place in the spring (May) and summer (August), in each second area between rows, in a vineyard with permanent green cover. In the case of PST experimental treatments, on average, 1892 kg of soil ha-1 yr-1 eroded, together with the nutrients. In the case of PGC treatments, the amountof soil erosion was only 92 kg ha-1 yr-1. The greater portion of erosive events occurred after tillage in summer, which was accompanied by heavy rainfall and slow renewal of grass cover (slower than in spring). PGC treatment provided a better environment for the activities of soil macro-organisms (i.e., earthworms belonging to the family Lumbricidae), and mostof the organisms were close to the soil surface. In PST treatment, the majority of macro-organisms were below the area disturbed by the tillage (between 10 and 20 cm). The results of our investigation indicate that, in order to adjust wine production activities to climatic changes in vineyards with permanent green cover, PST in area between rows is more advisable in spring (end of May) than in summer (first decade of August) owing to an earlier establishment of effective grass cover.