The influence of soil on the vine has stimulated more column inches in
the letters section of Decanter magazine, and more miles of Master of
Wine exam scripts, than any other topic relating to wine. How, and to
what extent, the soil affects wine quality remains the great philosophical
question.
Everyone agrees on a few basics. Vineyard soils need to drain well. Equally,
if irrigation is not an option, the soil needs to be able to retain some
moisture to see the vine through the summer. Furthermore, the vine needs
to draw certain key nutrients, like iron and nitrogen, from the soil.
So far, so good. It is what comes next that has exercised the great wine
minds of the last few hundred years. The empirical observation over the
centuries in Europe, and particularly in France, is that certain vineyard
plots pretty consistently produce wine with a distinctive discrete character.
Somewhere like Burgundy, a grower may own two neighbouring plots of land,
which he cultivates in exactly the same way, and yet the wines from these
two sites taste different.
Why? The vine's environment is thought to be responsible in some way.
The French word 'terroir' encapsulates elements like the soil, the slope
and the localised climate, which make no two places identical in terms
of environment. By extension therefore, no two wines from different vineyards
will ever taste quite the same.
Although the cultural gap is probably less now than it was in the past,
it is possible to say that a French wine's terroir is still seen as the
most significant determinant of its style and quality. By contrast, many
growers in the New World, whilst recognising the role of soil, aspect
and 'microclimate', would not accord terroir alone the semi-mystical significance
it has in parts of Europe.
The soils which are a component of the best terroirs in France are often
low in organic matter and quite poor. The vigour and yield of the vines
is thus naturally restricted. This leads to another much-argued observation
which is that most great wines are made from low yielding vines.
