Getting Back to the Soil with BC Pinot Noir

From my initial analysis of soil type with the vineyards associated with my BC Pinot Noir tasting notes using a Geographic Information System, I can see some regional clusters in BC.  I also see some commonality between the most common Pinot Noir vineyard soil types and the most common Riesling vineyard soil types that I analyzed last year from my BC Riesling Review .

Soil is very important for vines.  It’s where the roots grow deep and absorb the water and nutrients in the soil.  Following are some notes about soil from my BC Riesling Review, revised with the addition of soil types particular to BC Pinot Noir.

What is Soil?

Isn’t that a strange question?  We walk on it, build things on it, grow vegetables in it, but what is soil?

Soil is a very important part of the BC Pinot Noir Review as this is where the nutrients for the Pinot Noir grapes come from.  I will try to keep this article interesting without being too dry and academic, but sometimes you need to get a bit scientific and geeky in order to appreciate the end results of wine in your glass.

I am not a soil scientist, but I do have some basic knowledge of soils.  Soil, if you dig down has in general 3 zones, or horizons. The BC Ministry of Environment says this about soil: “…In mineral soils there are generally three major horizons; A, B and C. The A horizon is uppermost, where the maximum accumulation of organic matter in situ occurs and where maximum removal of materials occurs by solution, suspension or erosion. It is also where the largest transfers of energy take place, both solar and biological. This is truly where the action is! The B horizon is where the materials accumulate that were freed in the upper portion of the soil body. There is a close relationship between the A and B horizons. Translocations as well as many biological and chemical reactions take place between them. The B horizon, however, tends to be more stable than the A for short term differences. The C horizon is often termed the parent material. The effects of soil processes have not manifested themselves appreciably and thus the material is little modified…” (http://www.env.gov.bc.ca/soils/landscape/2.2soil.html)  The following figure from the Ministry shows a common mineral soil profile.

About 60 percent of grapevine roots sit in the top 24 inches (60cm) of soil, but many of the plant roots grow much deeper. Grape roots can grow more 20 feet (6m) deep. Soil texture and pH affect the development of grapevine root systems. As soil acidity, density and poor water movement increase, root vigor decreases. (http://homeguides.sfgate.com/grapevine-root-systems-59167.html).

Here is an example of a soil pit dug at Okanagan Crush Pad‘s Switchback vineyard in Summerland. I believe it is an Orthic Brown Chernozem.

Now that we know a bit about soil, what different soil types do we have in BC where our Pinot Noir grapes are grown?  The soil info presented below are again from the BC Ministry of Environment. I underlined parts of the descriptors below that I thought are interesting. Read on.

The Brunisolic Order

Soils of the Brunisolic order have undergone only moderate development from the original parent material. Physical, chemical and biological weathering has proceeded far enough to change the morphology of the parent material. There are a number of reasons for this sort of soil occurring in British Columbia. Firstly in many areas the climate has restricted the progression of soil weathering. Long winters and low temperatures restrict the rate of many of the transformations which constitute soil weathering. This is the reason why Brunisolic soils cover much of the high plateaus of northern British Columbia. Lack of soil moisture also limits transformations such as chemical weathering. Thus Brunisolic soils are also found in the sub-humid to semiarid zones of the southern interior.

Secondly, some Brunisolic soils have developed on very coarse textured materials such as fluvioglacial sands and gravels in areas where the climate is not normally a limiting factor in soil development. Because clay-sized particles, the principal active fraction in chemical transformations, make up only a small volume of the total mineral soil, little weathering has taken place. Most of the soil is relatively inert gravel and quartz sand. Moreover the parent material has a low water-holding capacity, so that soil water content is low and thus chemical transformations are further restricted. The droughtiness of these soils means that the vegetation is often limited to open lodgepole pine and pinegrass. (http://www.env.gov.bc.ca/soils/landscape/2.4order.html)

The Chernozemic Order

Soils that belong to the Chernozemic order are associated with a grassland vegetation and a climate which ranges from sub-arid to sub-humid. However, the most important characteristics of the climate as a soil forming factor are low rainfall, high summer temperatures and high evapotranspiration rates. This inhibits tree growth, limits soil leaching and leads to the accumulation of the decomposition products of the grasses in the topsoil.

The principal areas of Chernozemic soils in Canada are found in the Prairie provinces. But there are also significant expanses of such soils in the valleys and some adjacent plateau areas of the south central interior of British Columbia. The distribution of Chernozemic soils is mainly a result of the climatic limitations to tree growth. These soils are therefore found on a wide variety of parent materials. In valleys they occur on fluvial deposits or terraced lake silts as in parts of the southern Okanagan valley.

The dominant process in the development of Chernozemic soils is the accumulation in the topsoil of organic matter derived from the decomposition of the leaves and roots of the grasses. The organic matter is intimately mixed with the mineral material by its repeated ingestion and excretion by soil fauna. This gives a dark colored surface Ah horizon with well-developed granular structure. The low rainfall means that there is only a limited movement of water down through the soil profile and very little leaching. This means that there will be little movement of clay down the profile and carbonates will tend to accumulate in the C and lower B horizons due to high soil evaporation rates (Karl: Calcium Carbonate, e.g. limestone or chalk, can be found here and accessed by the grape’s roots).

The four great groups within the Chernozemic order – Brown, Dark Brown, Black and Dark Gray – are differentiated on the color of the surface Ah horizon. This is associated with organic matter content which is itself a reflection of the aridity of the environment. (http://www.env.gov.bc.ca/soils/landscape/2.4order.html)

The Luvisolic Order

Soils of the Luvisolic order are formed under deciduous, mixed deciduous-coniferous, boreal forest or under mixed forest in the forest grassland transition zone. Their parent materials are generally neutral to slightly alkaline and they usually occur in areas having more effective precipitation than do the Chernozemic or Brunisolic soils. In other words they are found in areas which either have higher rainfall or lower temperatures with less evapotranspiration. Therefore leaching of soil constituents and weathering are more intense than they are in Chernozemic or Brunisolic soils.

The dominant process in Luvisolic soils is the translocation of clay-sized mineral particles in suspension from the A to the B horizon. These form thin shiny layers of clay on crack faces and down pores. They are called clay skins and it is this Bt horizon which distinguishes Luvisolic soils from the soils of other orders. It can be an important horizon in the soil since the clay can accumulate so much that root and water penetration is restricted. These soils can be very wet in the spring.

(http://www.env.gov.bc.ca/soils/landscape/2.4order.html).  With our heavy rains in BC, I can see that these soils can be very wet, which could be a problem in the Spring, but if it occurs in the summer, it may allow retention of water and keep the grape vines less stressed.

The Major Soil Types Associated with the BC Pinot Noir Vines

We now have a bit of knowledge of the soils associated with the Pinot Noir grape vines here in BC, but which soil(s) were the most popular?  To answer this question I needed to overlay the vineyard locations with a map of soil type regions of BC. Using a Geographic Information System, (think Google Maps but more powerful), I overlaid the geographic (latitude/longitude) locations of the vineyards, (which were given to me by the wineries), on top of soil polygons which were mapped by BC soil scientists.   The soil map data reference is “Province of British Columbia, 2015, British Columbia Soil Mapping Spatial Data (a compilation of digital soil mapping datasets). Data available from the British Columbia Ministry of Environment, Ecosystem Information Section at:  http://www.env.gov.bc.ca/esd/distdata/ecosystems/Soil_Data/SOIL_DATA_FGDB/ [Accessed September 2015]“.  Through the overlay of these two datasets, I tagged each Pinot Noir vineyard point with a soil polygon, that contained information on soil type.  The table below shows the number of BC Pinot Noir vineyards that are associated with one of the soil types I outlined above.  Within these soil polygons, these soils represent the majority soil type.  There may be other soil types mixed in, but the other soils would be a minority.  As you can see, the Orthic Brown Chernozem soil type is the most popular for Pinot Noir plantings in BC followed by Eluviated Eutric Brunisol. Vancouver Island’s unique soil types also showed up: Duric Dystric Brunisol and Gleyed Dystric Brunisol.

A coarse overview map of the vineyard locations colour coded by major soil type does show some pattern.

Eluviated Eutric Brunisol

The soils for these 11 vineyards are well to rapidly drained with rainfall, and as such have a low available water storage capacity.  In general the soils are glaciofluvial, where the parent material has been moved by glaciers and then sorted and deposited by streams from the edge of the glacier, with the deposits making outwash plains, deltas, kames, and eskers.  They are characterized by having an eluvial horizon, Ae or Aej, at least 2 cm thick.  An eluvial deposit, is created by situ weathering or weathering plus gravitational movement or accumulation. The soils are medium to neutral with a pH in the range of 5.6-7.4 (where 7=water).  The soils may also be weakly calcareous (containing Calcium Carbonate, which may have come from the shells of small fossilized snails, shellfish, and coral). Chalk, limestone, and marble are all natural forms of Calcium Carbonate, and are actively sought for vineyards, to add sharpness to a wine and minerality.

The wineries with vineyards with this soil type are:

• Arrowleaf
• Tantalus (2 wines)
• Seven Directions (Kalala Vineyard)
• CedarCreek Estate Winery (2 wines) (Platinum Block 2 and 4)
• Meyer Family Vineyards (Reimer Family Vineyard)
• Black Cloud
• 50th Parallel Estate
• Liquidity
• Volcanic Hills

Orthic Brown Chernozem

This is the most popular soil type for the Pinot Noir wines that I tasted (also for Riesling).  17 wines come from this soil type.  This type of soil is well to rapidly drained with intermediate to low water storage capacity.  This soil type is made of glaciofluvial, glaciolacustrine and fluvial sediments.  Glacio meaning that the parent material was moved by glaciers, and the sorting and deposition by stream melt, river channels(fluvial) and deposition into lakes (lacustrine).  The soil would be made of mainly sand and gravels and you may see geomorphological features such as outwash plains, deltas, kames and eskers.  If the deposition was glaciolacustrine then the soil would have moderate to very strong calcium carbonate presence, otherwise if fluvial or glacialfluvial then calcium carbonate would be very weak.

The wineries with vineyards with this soil type are:

• Thornhaven Estates (2 wines)
• Seven Directions (Canyonview Vineyard)
• Haywire (2 wines) (Canyonview Vineyard)
• Noble Ridge Vineyards & Winery
• Meyer Family Vineyards (McLean Creek Vineyard)
• Fort Berens Estate Winery
• See Ya Later Ranch
• Sumac Ridge Estate Winery
• Tightrope
• Burrowing Owl Estate Winery
• Joie
• Gehringer Brothers (2 wines)
• Hillside Estate Winery

Orthic Dark Brown Chernozem

This falls into the well drained soil and has lower water storage capacity.  The soil material came from glaciofluvial and fluvial deposits.  You should again see gravel and sand in the soil, and have a moderate to very strong calcium carbonate component in the soil.  Will this give the Pinot Noir wine from this soil, sharpness and minerality?

The 5 winery vineyards with this soil type are:

• Gehringer Brothers (2 wines)
• Robin Ridge
• Evolve Cellars
• SpierHead Winery (Golden Retreat Vineyard)

Rego Brown Chernozem

In the Rego Brown Chernozem soil, water is removed from the soil steadily to rapidly. It has intermediate to low water storage capacity.  The soils come from glacial ice contact and glaciofluvial processes.  These deposits are stratified and may occur in the form of outwash plains, deltas, kames eskers, and kame terraces. The soil should be medium to neutral acidity, and weakly calcareous.

The winery vineyards with this soil type are:

• Bench 1775
• Nk’Mip Cellars
• Moraine

Orthic Eutric Brunisol

This type of soil drains water away rapidly and therefore has a low available water storage capacity.  The soil comes from glaciofluvial materials where glaciers transfer the parent material and melt streams sort and deposit the materials, which can form outwash plains, deltas, eskers, and kames. The soil should have medium to neutral acidity with a pH range of 5.6 – 7.4 (water is pH 7).

The winery vineyards with this soil type are:

• Niche Wine Co (2 wines)
• Baillie Grohman

Eluviated Dark Brown Chernozem

Water for this soil type is removed from the soil readily but not rapidly.  It has medium to neutral acidity. The soil materials were moved by glaciers and subsequently sorted and deposited by streams flowing from the melting ice. The deposits are stratified and may occur in the form of outwash plains, deltas, kames eskers, and kame terraces. The soil is moderately to very strongly calcareous.

The three wineries with this soil type are:

• Arrowleaf
• Sperling Vineyards
• Upper Bench Estate Winery

Duric Dystric Brunisol

Orthic Regosol soil drains slowly, and has high water storage capacity.  The uppermost portions of this soil horizon comes from marine deposits of clay, silt, sand, or gravel that are well to moderately well sorted and well to moderately well stratified (in some places containing shells).  Deeper there may be glacial till. The soil has strongly to extremely strong acidity.  Without tasting the wines from this soil type I would not have had a guess as to the quality of the grapes or to the aromas and flavours, but I am pleasantly surprised.

The winery vineyard with this soil type is:

• Blue Grouse Estate Winery

Gleyed Dystric Brunisol

For Gleyed Dystric Brunisol, water is removed from the soil sufficiently slowly in relation to supply, to keep the soil wet for a significant part of the growing season.  Gley is Russian for “clay”. The soil comes from glacial moraines (till) forming a mixture of boulders, sand, silt, and clay.

Water saturation leads to depletion of oxygen in the soil and soil features associated with oxygen-depleted (also called anaerobic or anoxic) conditions. When oxygen becomes depleted (due to water saturation) the iron is reduced and takes on a blue-grey hue and this dominates the colour of the horizon.  The water-saturated conditions also reduce the rate of transformation of organic matter in the soil. This can lead to the build up of organic matter on the surface of the mineral Gleysolic soils.  Prolonged water saturation over time can produce peat soils.  (from https://soilsofcanada.ca/orders/gleysolic.php)

The winery vineyard with this soil type is:

• Averill Creek

Orthic Grey Luvisol

Orthic Grey Luvisol is readily, but not rapidly drained.  Soils come from glaciolacustrine deposits; lake silts, kettles, slumps, and ice rafted stones.   The soil is moderately to weakly calcareous.

The winery vineyard with this soil type is:

• Quails’ Gate (2 wines)

What’s Next?

Here are our vineyards classified by major soil type.  There are preferred soil types as we can see from the chart, and some wineries growing their Pinot Noir grapes on more unique soils.  The next phase of this Review is to aggregate aromas and flavours by major soil type.  The results from the Riesling analysis was very interesting and I’m sure it will also be interesting for Pinot Noir.  What characteristics may come from these soils?

FYI, the first part of the BC Pinot Noir Review was a listing of all the wines I tasted, along with my detailed tasting notes.  You can read my BC Pinot Noir tasting notes at these links below:

• First Round of BC Pinot Noir Wines Reviewed
• Second Round of BC Pinot Noir Wines Reviewed
• The Final Round of BC Pinot Noirs Reviewed