Of Wines and Soils

by Jim Law

As our industry expands, new growers are looking for recommendations on varieties, clones, rootstock, vine spacing and trellising systems. When I ask about their site’s physical soil characteristics, most are clueless. This is because we as an industry have placed very little emphasis on soil. Over the past 10 years we have made great progress in understanding microclimates. Today most new plantings are going into sites much better suited for consistent, economical production. As we focus more on quality I believe that there will be much greater priority and understanding on the relationship of soil and good wine.

The Old World has the highest respect for this relationship. We are all well aware of this as it is reflected in reputation and therefor price. The New World sees climate as a more important factor. We are always reminded of a certain vineyard’s cool coastal valley, high elevation, or location near something physical that influences its microclimate. Being in the New World, we in the East are towing the party line…climate over soil.

When looking at wine quality, the most important characteristic of a soil is drainage. All the best vineyard soils in Europe have this one thing in common. This is because in Europe the water comes from the sky throughout the growing season and, most importantly, during harvest. A soil that loses this water quickly produces wine with the greatest concentration. On our West Coast and in Australia the water comes from the ground. They control it. They turn it off at harvest time. Soil drainage doesn’t play as significant role. Here in the East we are most influenced by our West Coast and Australian colleagues because of our shared language, culture and ease of communication. This is often unfortunate, as I believe Europeans have more sage advise to offer.

It took me over 20 years to truly understand how important soil is to making great wine. It will probably take even longer to achieve better soil, vine, and wine balance. I have found that older vines and red wines express soil differences with the greatest distinction. I am organizing my efforts on achieving better wines by focusing on soil/vine interaction in a practical sense:

1. Identification of soils

Within my twenty acres of vines I have dozens of soil differences. Drainage, depth, water holding capacity, organic matter, cation exchange capacities vary considerably. I have learned this over the years by observation and taste. Recently I confirmed my intuition with a visit from a soil scientist.

2. Matching variety to soil

I am now beginning to understand what soil Cabernet is happiest in and which soil Chardonnay likes best. I didn’t get it all right when I planted, so I am now experimenting with grafting over varieties (the jury is still out). I am agonizing over whether to start pulling out healthy, but mediocre quality vineyards and replant with a more appropriate variety for the soil.

3. Matching trellising and spacing to soil

I am becoming somewhat comfortable in knowing which trellis system works in which soil. I use 3 different trellising systems, GDC, Lyre and VSP. Initially I tried to match variety to trellising system, but the more I learn, I am seeing that matching trellising system to soil makes more sense. VSP is best on my poorest (best!) soils, Lyre on my moderately vigorous soils and GDC on my vigorous sites. Vine spacing will take a lot longer to resolve. Vine spacing has become a moving target because my vines devigorate after about 10 to 15 years. What is appropriate for a 6 year old vine does not always work when that vine is 15 years old. I have not found that close spacing results in vine devigoration through root competition. As a rule of thumb I find that the more vigorous the soil, the wider the spacing. 6 feet between vines is the norm with 4 feet for low vigor soils and 8 feet for high vigor soils.

4. Harvesting by soil

After harvest one of my jobs is to take down all the surveyors tape strewn all over the vineyard. More and more we are harvesting by soil as we find different rates of ripening, quality and flavor profiles. I use lots of flagging tape to designate where the picking should be confined to on a given day. Unfortunately, in many cases our rows straddle different soils and sections have to be picked at different times. We vinify these lots separately and then taste blind for triage, blending, and archival information.

The Eastern United States has only just begun the long evolution of developing new viticultural regions. There is a lot of good scientific soil data that we are not yet fully utilizing. Even more importantly, as our vines and we mature, a certain intimacy will evolve between winegrower and site that will give us the opportunity to move from making good wines to great wines.

Someday the idea of planting a neat, tidy, rectangular ten acre “block” comprising several varieties all on the same trellising system and on many different soil types will seem silly to all of us… Should we live so long.