Why is it that everywhere I read about high levels of calcium carbonate in soils and the resultant higher pH of the soil, inevitably 'produces high acid wines' shows up? What is the chemical reason for this? I know that nutrient uptake is effected by the soil pH and that soils with a pH too low or too high will inhibit specific nutrient uptake but this still doesn't seem to explain why acid is higher in higher pH soils. Help please.
The quick and dirty version (detailed botany being beyond me at this stage) is this: grapevines are primary soil builders; they have adapted over many millenia to break primary rock into basic soil. To do this the vine has evolved the ability to excrete acids that dissolve said minerals - and while the vine may be able to partially compartmentalize what it synthesizes in the roots to break down the soil, it can't completely (for comparison think about the way partial root zone drying irrigation works) - therefore if the vines roots are synthesizing more acid (to break down a more basic soil) every component of the vine will consequentially be more acidic - including the grapes.
The tie in to quality then comes where one of the key markers for "classic" status as well as quality is the ability to age - and given that the majority of oxidation reactions that we think of as development are heavily inhibited at lower pH (remembering that pH is logarithmic), wines made from acidic grapes from basic soils age more slowly, develop more gracefully, and are consequentially of higher "quality" than their more everyday counterparts.
This doesn't sound quite right to me. Can you point me to the source(s) of this information?