The Collio, one of the best white wine producing areas in Italy, is a small range of hills formed during the Eocene and situated in the extreme eastern part of northern Italy. In reality it is part of a more extensive chain of higher elevations which runs from the north of Udine south east to where it ends deeply wedged into the Istrian peninsula. The substrate is made up of sedimentary rocks with characteristics which are probably unique. It was formed on the bed of a shallow sea where softer sediments (marls) alternate with harder ones (sandstones), which lend this terroir its originality and workability. In fact it is thanks to this discontinuity in the bedrock that small quantities of water are able to trickle through the strata to be taken up by the roots of the vines during periods of drought. There were several lagoons which gave rise to these Flysch formations, and the one from which the northern Collio was formed was the most northerly of them, the same one that formed the Colli Orientali del Friuli (Eastern Friuli Hills) and the Brda which is the continuation of the Collio beyond the Slovenian border. For this reason, the soil characteristics in all three areas are virtually identical.
The Collio is around 20 km from the Adriatic, separated by a narrow coastal plain. Thirty kilometres to the north are the first steep slopes of the Alps. There are marked climatic differences between the hillsides which face the mountains and those which face the sea due to the influence of winds; those from the mountains are colder and drier, while the onshore sea breezes are warmer and more humid. The microclimates vary both with altitude and orientation, facing either the mountains or the sea. This is because the mountains act as a barrier to the winds, but also because of how cold air currents from the mountains gradually heat up as they move towards the sea. Moreover, the orientation of the slopes has an important physiological influence on the vines. They, like all other plants, use their leaves to trap the energy from sunlight which is necessary for their growth; so the flat surfaces of the rows of vines can be compared to a solar panel.
On the eastern slopes the vines catch the “clean” light of the morning whereas western facing plants will get “dirty” afternoon light with its higher payload of moisture. Seeing as, during the hottest parts of the day, the vines close their stomata in order to limit transpiration, we find that photosynthesis takes place in the east with clearer light and at lower temperatures which are good conditions for laying down aromas, and hence for aromatic varieties, whereas in the west with less clear light and higher temperatures we have good conditions for whites grown on warmer slopes like Tocai (now Friulano) and Malvasia and for the maturation of polyphenols in the reds.
Differences also exist in the terrain. Even though the geological background is the same and the stratifications of the various Flysch types are similar there are however highly localized variations in the chemical composition of the rocks. Hence we must expect the environment to have an important impact on the vines. In 1982 we began processing grape batches from every patch of vineyard separately, and to record all of the salient facts arising during the vinification process. With the aim of highlighting the influence of the “terroir”, between1992 and 1995 the cellars were completely restructured and all the containers renewed so that we could make wine separately from each batch of grapes and to get it safely into bottles in quantities in excess of 250 litres. Thanks to data gathered over the years using the method we have explained, we are gaining an ever deeper knowledge of our principal vineyards.