I have talked in this forum more than once before about the very high degree of variability in Norway spruce trees. In my previous posts I have emphasized the importance of having the right genetic strain for each area of the country--the right seed source or provenance.

Another issue I have discussed here is the possibility--I think a very high possibility--that Norway spruce trees are damaged and or killed by improper applications of soil acting lawn weed control chemicals. I don't have anything approaching good scientific evidence for this, but I have observed a possible cause/effect relationship of this kind so many times over the 30 years or so that I have just about concluded that it is fact.

Now I want to present another hypothesis about Norway spruce growth. Again, I have nothing like scientific evidence for my specific hypothesis, but there is a large body of scientific research that is at least tangentially related.

Here is my new hypothesis: That Norway spruce trees, especially those growing on strongly acid, and even moderately acid soils not especially high in magnesium content, can benefit from applications of pulverized or pelleted high magnesium limestone, even when there are no symptoms of any magnesium deficiency.

There has been a good deal of research on the causes and treatment of the so called "forest death" that has occurred in parts of the Black Forest in Germany, and in forests in other parts of Europe. Much of this research has focused on Norway spruce trees. The problem has been determined to be at least partly a magnesium deficiency aggravated by acid rain, air pollution, and drought. Applications of magnesium have proved to be beneficial. You can review this research on-line by using "spruce magnesium deficiency" for your search.

My hypothesis here is something very different from what that research has shown. Basically it is this: that seemingly healthy Norway spruce, but spruce that seems to have relatively poor growth and generally thin foliage, etc., can be made to look much more healthy and lush by the application of high mag limestone to the extent that the Ph and the amount of magnesium in the soil is brought well above the minimum levels needed to avoid specific symptoms of any deficiency.

In a nutshell, those of you who have poorly growing or unattractive Norway spruce trees may have a remedy.

I have been a careful studier and observer of Norway spruce for something like 30 years. I have had this hypothesis in mind for about 20 years now, but the only evidence I have had has been casual observations. More and more these casual observations have led me to think about this more and more. This last weekend I made an observation--again, not a carefully scientific one--that has prompted me to finally post this.

I visited the Morvin Park Estate in Leesburg, VA. I had visited this estate several times before. There are a good number of Norway spruce planted there. Almost all of them from all appearances, including their age, would seem to be a single planting from a single seed source. Most of them are relatively attractive, but not especially so. Now what really grabbed my interest at this visit was one particular Norway spruce tree. It is like all the others in its very basic appearance, including the cones. I had seen this tree each time I had visited the estate before and took no special notice of it--it seemed much like the others. But this time I was, and this may not be too strong a word, simply "shocked" by what I saw. This tree was so incredibly lush and full with dense foliage of a wonderful green color, that it looked like a completely different kind of tree from all the other Norway spruce trees there.

Anyone in the area can visit this tree--it is the first one you see as you take the path from the parking lot up towards the estate house. It is about 150 feet or so up from the parking lot.

OK, here is my hypothesis. How could that tree be so different from all the others on the estate, and seemingly so improved from what it looked like a few years ago? What could be different? What could be the cause?

This Norway spruce tree is the only one growing in a special garden area, the area where the most prominent former owners of the estate are buried. There has been in recent years a large project to restore the estate house, and along with that, some new special attention has been paid to the garden area. It looks like it has been more carefully attended, and here is the key, I am guessing, yes, just guessing, it has been fertilized, and the grassy areas, including that under and around this tree, treated with "lime."

There are a number of limestone quarries in the area, and many if not most of those produce high mag limestone.

OK, this is just one observation, but I have made many, many other similar ones. Just for one more--at the Virginia Arboretum there are a lot of nice Norway spruce trees. I have posted pictures of them here in the past. The best of those at the Arboretum are those growing next to if not virtually on top of limestone outcrops. The limestone in the area is a very high mag variety. Those further away from these outcrops where the soil is very deep above bedrock, do not look nearly so good.

Well, enough--I could cite one or two dozen more "observations" like these.

So here is what you can do. If you have Norway spruce trees that are not now perfectly gorgeous, and want to experiment on the basis of my hypothesis, apply high mag limestone at a rate of 4 pounds per 100 square feet under and around each tree to a distance of about 20 feet or more from the trunk. If you have soil that already has a high Ph, you need to be careful that you don't raise the Ph too high. One study suggests that the optimum Ph for Norway spruce is between 5.2 to 5.8. Of course what is the optimum Ph could very with soil type. If limestone is applied, the Ph on a light sandy soil will be raised more than it will be on a heavier soil. And soil depth is also a factor. So be careful. But the risks of the treatment I am recommending are very slight. I don't know that there is any chance you can raise the magnesium levels too high. I am not recommending using any other method to raise the level of magnesium.

The effects of the treatment I am recommending will come slowly--probably the results will take 5 years or more to be realized. It requires a year or so for the limestone material to sink down into the soil much at all. The uptake of magnesium in needles already formed is minimal, at best, and Norway spruce retains old needles for 6 years or so. So it will be 6 years before all the needles on the tree have improved levels of magnesium. And it also takes time for older trees to grow enough to show improvement in the density of their foliage, etc.

Yes, I repeat, this is all rather unscientific. I have searched for information about the effects of some kind of optimum Ph and magnesium levels for Norway spruce. I am not aware that any research has been done. And it is unlikely that any will be done any time soon. At my timberland I did an application like what I am recommending about 16 years ago. In one case, especially, the "results" have been dramatic, but I can't be sure some other factor was not involved. This fall I will more carefully select a few trees to treat in locations where I think any results could be less likely to come from other factors, and leave other similar trees untreated. This time there will be better reasons to think that any results I may see will be meaningful. I will report back in 5 years or so.

But I am confident enough about the possible benefits of this treatment, that I have spread high mag limestone around all my Norway spruce trees here at my home near Winchester, VA. Almost all look very good so far, but maybe they could look even better.

One hint--the "pelleted" variety of limestone is much easier to spread than the pulverized limestone. The brand I used here is produced by Stuart M. Perry of Berryville, VA. The analysis is:

Calcium oxide (CaO) 28.5%
Calcium carbonate (CaCO3) 51%
Magnesium oxide (MgO) 19%
Magnesium carbonate (MgCC3) 40%
Calcium carbonate equivalent 90%
Effective neutralizing value (ENV) 75%

These numbers I believe are typical of what is called "high mag" limestone. Another type of limestone that is high in magnesium is dolomitic limestone.

On the bag the recommended applications are: 1 bag (40 pounds) per 1,000 square feet to maintain Ph, and two bags to correct acidic soils.

Elsewhere I read that 40 pounds per 1,000 square feet could raise the Ph by .2 to .4. But I don't think there is much risk that the kind of application I am suggesting will raise the Ph of the average soil by enough to do any harm. But if your soil already has a Ph above 6.0, I would be careful, especially if the soil is light sandy soils and not very deep.

Of course, various soils have very different levels of nutrients, including N P, and K, and these can affect the soil reaction and Ph levels, and the Magnesium availability. Soils are not a simple one dimensional kind of thing. In addition, the depth of any soil is important, and the Ph levels near the surface can be very different from levels deeper in the soil.

I add all this so no one makes any mistake in thinking soils are more simple than they really are.

--spruceman

--Spruce

The area where I live is underlain by dolomite. There are many rock quarries where this material is blasted, crushed, and sorted into everything from ag. lime to "breaker run" heavy-gauge stone for road building, riprap, etc. Screenings are readily available and inexpensive last time I checked.

So now you've got me thinking.....the land where my plantation is lies at the very transition point between the soils we've got here and the much more acidic, sandy and granite-derived soils that make up much of the north. This is still farming country-my field where I'm planting trees is an old farm field that was alfalfa for years and is now corn, but is of a definitely different character to the heavy, loamy clay-based stuff around here. The corn up there this year actually did better than in the serious farming country further south, but that was because it rained up there this summer, unlike those more southerly areas.

What I'm wondering about is just how practical it would be to transport trailer loads of these screenings up there, for distribution around and under the NS sections of my plantation. At 4 lbs. per 10 sq. ft. that would run into quite a bit of material. But as you know, I share your fondness for really well-grown NS, and it is not beyond me to take this on.

Any thoughts, Spruceman or anyone?

+oM

When I dug up this old post, I thought I was in "Conifers" which Spruceman recently became active in again. Wonder if there's a way to notify him that this thread is back up here.

+oM

Yes, I'm here. I assume it is just a typo when you said 4 pounds for 10 square feet--of course it is 4 per 100.

But that is still a lot for a forest planting, but not impossible especially if one has a mechanical spreader of some kind.

It has been just 2 years since my original post here, so more time is needed, but so far the trees at my timberland that I gave some high mag limestone to SEEM to be showing some early benefit, but it is really too early to tell. Also, those trees are growing on soils that I believe have good levels of magnesium anyway, so any improvement may not be dramatic.

One point to remember is the magnesium is especially important for the foliage, and Norway spruce typically hold their needles for 5 years or more, so the benefits will build up over time. And, it takes at least some time for the magnesium to get down into the soil. With the pulverised limestone form, this will be substantially quicker than with a granulated form.

I have also made some more informal observations of Norway spruce growing in different areas. First, here in the Shenandoah Valley where the soils were formed over a high mag limestone, even though the climate is very hot, and has relatively low precipitation, especially in the summer relatively speaking, the Norway spruce have nice lush foliage. The limestone origin soils in the valley here run in bands oriented generally SW to NE. Soils outside these bands probably have less magnesium, and I see very few Norway spruce of any kind there. This could be because those soils are generally much less fertile, and are, at least in some cases, excessively well drained.

Also, in a couple of areas where I drive to get to my timberland from here, the Norway spruce are spectacular for their lushness. They are not especially large because of the hot dry climate, but they are gorgeous. I have not tested the soils for magnesium, but I would bet it is very high.

toronado: I don't think any test with seedlings would show much, if anything. First, the main effect I have observed--or think I have observed (I want to be careful here)--is not in growth rate, the growth in height. Now there might be an effect, but I am not sure. Of course, you could try.

But with seedlings, any difference in the fullness, or lushness of the foliage, would not show up until the trees are much larger.

The best experiment would be for someone living in an area where the foliage of Norway spruce looks rather thin, to give a good application, maybe a bit more than I recommended in my original post, and then wait 5 to 10 years and see if there is a difference. Maybe take "before and after" pictures.

Part of my hypothesis is that the benefits of Magnesium don't depend only on reaching a minimum required amount. It is my belief that there is an optimum, probably varying according to other soil factors, that may be substantially higher than that needed for generally healthy Norway spruce, that can result in really especially healthy and beautiful Norway spruce.

For those of you who have posted in this forum before about how the Norway spruce you see don't look very beautiful, All I can say is you are really missing something. I have a very strong suspicion that the reason is low magnesium in your soils. This is correctable!

Well, I make no promises, but I do have a belief, fairly strong, that I would like to see verified--or not.

--spruce

Similarly, somewhere there's a research paper stating that the soils on which certain rhododendrons in China grow have a higher than expected pH, but the ratio of cations favors magnesium and, IIRC, manganese over calcium, compared to most mountain soils around the world. But the optimal ratios of Ca/Mg in plant physiology for most species is highly in favor of calcium. See this discussion: http://forums2.gardenweb.com/forums/load/soil/msg0311011017714.html Some soils are so high in Magnesium and certain other minerals, that not even Picea abies can grow well: http://aob.oxfordjournals.org/content/95/4/661.short It's likely that each species has a preferred range of Ca/Mg/trace concentrations depending on its habitat, and it's quite believable that our more weathered soils here on the eastern US are low in Magnesium compared to the high-elevation soils in Europe.

NB that to correct mucky, marine clay soils closer to the ocean than the Shenandoah Valley, only the alkaline Ca++ ion can displace Na, and Mg in a reaction that causes the particles to aggregate into larger clumps, improving drainage. This is the reasoning behind using Calcium sulfate aka gypsum, although many such soils at least along the eastern seaboard are so acidic that there's no reason not to use calcitic limestone instead. (Also, the rain's so acidic here, it's going to quickly neutralize the lime lying on the ground. http://www.ekcsk12.org/faculty/jbuckley/leclass/usacidrainmap.gif There's no reason to add more sulfate when the rain already has very dilute sulfuric acid in it.) This is why I use both dolomite and standard limestone for different purposes. A portion of my lawn that was a mucky quagmire has been converted back into healthy, draining soil with calcitic limestone - it takes a couple years, and I don't advise everyone try this unless they are sure of local conditions warranting it.
I finally direct anyone interested to this article:
http://www.soilminerals.com/Cation_Exchange_Simplified.htm

Thanks!

Poaky: The growth of any one norway spruce tree could be just that that individual tree is a runt. In any planting of Norway spruce, some grow much faster than others, and some very slowly. This is true even if the seed source is a good one.

The effect I believe I have seen from good magnesium levels in my area is more lush and dense foliage, not in rate of height growth, although I suspect that would benefit also, if not so dramatically.

Yes, if your pH is 6.7 I would try an alternative source of mg. But if they look good, maybe more magnesium will make no difference, and it might be possible to overdo it. Maybe you should leave them be as they are.

-spruce

Just for the sake of conversation, I have noticed that NS appears to do especially well in S. E. Wisconsin, in particular, that area just north of the city of Milwaukee. My older son just bought a house in Cedarburg and that pictureque town is just full of big, tall, good-looking NS. As is true of the surrounding area.

Thanks all for a great conversation.

+oM

Are there any Norway spruce in the general area where you have your land? Any observations about those? If they look just average, I bet they could benefit a lot from some high mag limestone.

If I have a bit of spare time I may get out a map and see if I can find out anything about the soils in the area north of Milwaukee where you see really good NS. Generally these surveys don't comment directly about mg content, but they do describe the development and origin of the soils. If they were derived from some kind of limestone, that will be discussed, as, of course, will be their fertility.

Next time I drive up to my timberland I will try to take a picture of a nice spruce tree or two along the route that are especially lush with dense foliage. The picture I posted in my original post is a very nice example, but maybe another picture or two will help people understand what really good NS can be like.

--Spruce

Up to the north, I do see some that look real good and some that look less than great. I think that for consistently impressive specimens, that area N. of Milwaukee is the best I've ever seen. And possibly due to strong German immigration to that area 100+ yrs. ago, many, many of these trees were planted. They're everywhere.

It seems plausible too that the effects of proximity to Lake Michigan could be in play. All of the area I'm talking about is within a distance of 20-30 miles from the big lake. Mostly much closer. For reference, I'm talking Ozaukee, Sheboygan, Washington, and Manitowoc Counties. Mostly, the first 3.

+oM

But this time I was, and this may not be too strong a word, simply "shocked" by what I saw. This tree was so incredibly lush and full with dense foliage of a wonderful green color, that it looked like a completely different kind of tree from all the other Norway spruce trees there.
****

Believe it or not, I had the same reaction at some point about NSs I'd planted ~1973 where I grew up. I'm pretty certain these were all from the same seed-source. Most are now 70' trees -- handsome but typical. One stands out though -- the "runt", at least at first (prb'ly because it was originally relatively shaded/sheltered). But now it looks very much like the Leesburg tree -- long, elegant branches (not as big of course). The soil is very good "Hagerstown loam" w/some outcrops of limestone, but generally moderately acidic (pin oak grows well).