Why some high calcium soils produced excellent grapes
By Neal Kinsey, Kinsey Agricultural Services
One quandary that continually presents itself for vineyards as well as other crops is why some high calcium soils produced excellent grapes while others in the same vicinity (and sometimes the same variety in the same vineyard) looked and tested exactly the same, but were of less quality and at times even a definite problem in terms of the wines produced.
When that happens, could it be the soil test being taken incorrectly? It could be, especially if there are wide variations in the soil test numbers, and particularly the expression of cation exchange capacity, from year to year. But what if the soil tests are basically consistent from year to year and look the same in the good and bad areas?
First, consider that when results seem inconsistent from the use of the same methods that can ordinarily identify why soils have good or average or poor fertility, something more must be considered. There is usually a good, common-sense answer, we just must search to find what it is and use it to solve the problem.
We have worked with soils producing from excellent to extremely poor wines that measured exceedingly high in calcium since the 1970’s. From that experience it has become evident that the problem is more than just too much calcium, as some soils with higher calcium levels produce better wines than others that have lower concentrations in the soil where poorer results have been experienced.
Considering all the soils that were analyzed from year to year, the problem seemed relatively rare, but still the problem was always present in enough soils to be of concern and continue looking for a sensible solution. These different areas are not normally submitted for a comparison. Most of the time such soils were either doing well or doing poorly, not enough of both in the same vineyard for growers to be sufficiently concerned to pay the cost and have both analyzed separately. And the few times it was done, the good and bad soil all looked to be bad.
Around 2005, while reviewing some of the original work of Dr. William Albrecht there was a clue that just “jumped out” from a page on his explanation of measuring cation exchange. He explained that the sum of the cations was generally the best approach to determine the soils cation exchange capacity due to the costs involved, but there was a more accurate way it could be used to establish that number. But he did not say what it was. Still his comment was sufficient enough to point out that, though generally too costly to use for the general soil test, there is a more effective way to determine how many positively charged cations can be attracted and held on the surface of soil particles until enough acidity from plant roots or soil microbes could release them for use by the plants growing there.
For years some concerned educators and consultants had asked the question, “But when you measure calcium, what about the influence of free calcium?” This was referring to the amount of calcium in an available form in the soil which was so plentiful there could not be enough negatively charged clay particle for all of them to be attracted and held – adsorbed – by a more limited number of clay colloids present?
Here was a possible way to differentiate between how much calcium was present in a soil, but also how much was able to be attracted and held and how much more was present that had no negatively charged clay particles to attract and hold them – thus the “free calcium” still there that influenced the sum of the cations, but the assumed negatively charged clay particles were not actually abundant enough to be holding them along with the other normally needed cations, namely magnesium, potassium and sodium.
Since the “sum of the cations” was used to calculate the amount of negative charge provided by a matching amount from the clay colloids in a soil, the Cation Exchange Capacity was thus overstated. This also eventually showed that the amounts needed of the other cations (especially Mg, K and Na.) when extremely excessive in a vineyard soil can also be overstated, making it appear such soils needed more than they could tolerate.
This was the beginning of the process that ultimately helped determine and define not only soils that had too much calcium, but also magnesium, potassium, or sodium, or some combination of those. This was then causing the “sum of the cations” to over-inflate the amount of negative charge (expressed as the cation exchange capacity)?
This took time to work out and discover, it did not all come to be understood at once, because there was no protocol developed to determine all of this at the time. The initial efforts began with the crop of 2006, but it took years of actual field work to solve the myriads of problems this has created. And that field work was based on results that when achieved more than paid for what needed to be done and increased profits by increasing either yield or quality and oftentimes both at once.
Initially it was thought that only a few dozen such tests would be needed based on the volume of soil we saw before beginning this project. But as the results became evident and the word spread to others with similar problems in their grapes, that numbers has grown to be hundreds per month, especially from the extremely high calcium soils of the Western United States, Austria, France, and Germany.
In fact, reputable long-established wineries from Europe have sent samples for analysis with no mention of such a problem, but by doing the tests properly, it was possible to point out what was happening. One example was a winery that had a history of many prize-winning wines, but the soils they submitted did not reflect that. And when we pointed out that these were problematic vineyard soils, the owners admitted that on these vineyards the quality of the grapes had been slowly declining over the last 20 years, but the soil tests still appeared to be the same as when the vines were doing their best.
The normal soil test does not detect such problems, even if you can identify and test the areas good and bad. An extra test that adds another 50% to the cost of each test must be performed and there is no protocol that has been written up and described to do so. The reason it can be done is due to actual hands on “field” or vineyard soil work.
The key is in soil chemistry that applies to the verified saturation of all the nutrients most involved in affecting the soil pH. This type of experience is not written up and published to this point, because the results are from on-site experience, not officially randomized, replicated experiments. The only way to learn it works is by doing this type of testing and following through with what is necessary on each specific vineyard soil. Because the circumstances can vary greatly from one soil to another, perhaps the best way to learn if there is merit to the process is to send two soils – one from the good and one from the bad, or to increase the odds of a lucky guess, several bad areas to see if they can be correctly identified and why.
Until Cation exchange capacity and base saturation of nutrients are accepted as a valid way to conduct that research it is not likely to be considered for research, because it is the only testing method at present to identify the differences that exist and need to be corrected to achieve the proper results.
True science begins with observation. Using the proper tests both the good and the bad and the reasons why can be determined.
“We can always prove a definite theory wrong. Notice, however, that we never prove it right.”
Richard Feynman (1918-1988), American theoretical physicist & Novel Laureate
