Ask a Question forum: Acidifying soil where lilies are planted

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Name: Kamasamudram Ravilochan
Denver, CO (Zone 5a)
kravilochan
Apr 30, 2017 7:34 PM CST
I have inadvertently planted, about 6" deep, three different types of Oriental Lilies (Casablanca, Canberra and Nymph) and later on found that the soil (mostly clay) is alkaline with a pH 8.4. I would like to amend the soil just in this area but would prefer to do so without disturbing the soil (not digging deep, lest I damage any emerging sprouts) and make the soil acidic. The bulbs have been planted about 3 weeks ago now. Is there any way I can make the soil acidic by just adding something on top? Any helpful suggestions would be greatly appreciated.
Name: Bob
Vernon N.J. (Zone 6a)
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NJBob
Apr 30, 2017 7:41 PM CST
http://www.wikihow.com/Acidify...
See if this helps.
Name: Carol
Santa Ana, ca
Sunset zone 22, USDA zone 10 A.
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ctcarol
Apr 30, 2017 7:53 PM CST
Wow! That's a great article! Helps me, and I've been gardening all my life.
Name: Kamasamudram Ravilochan
Denver, CO (Zone 5a)
kravilochan
Apr 30, 2017 8:16 PM CST
NJBob said:http://www.wikihow.com/Acidify-Soil
See if this helps.


Thanks for such a prompt response, Bob. That's is very helpful. So I am thinking of Aluminum Sulfate as a quick fix, but later in the year, will consider adding more organic material like peat moss. Please do correct me if my logic isn't sound.

Name: Rj
Just S of the twin cities of M (Zone 4b)
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crawgarden
Apr 30, 2017 8:27 PM CST
https://carteret.ces.ncsu.edu/...
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Name: Sue
Ontario, Canada (Zone 4a)
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sooby
May 1, 2017 5:43 AM CST
Clay soil resists changes in pH more than a sandy soil and 8.4 is pretty high and may be difficult to lower. There are differences in western soils that you may need to take into account. Did you get that figure from a lab test or a home test? Typically a lab test will also give you suggestions as to whether it is practical to lower the pH and if so how much acidifier to use based on the buffering capacity of your soil and how much you need to lower it.

This article is specifically about Colorado soil pH and things to consider regarding attempts to lower it.

http://www.ext.colostate.edu/m...
Name: Rick Corey
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RickCorey
May 1, 2017 6:03 PM CST
I would vote for a bag of "ag sulfur". Microbes have to digest it to activate it, so it will acidify soil slowly and safely. (It's very hard to make sulfur burn anything!)

What I think is cool is that the elemental sulfur is digested by microbes into ... sulfuric acid!

Well, really it gets turned into Sulfate ions (a micro-nutrient or semi-major plant nutrient) and the extra acidity created by that microbe's digestion is just absorbed by whatever is most basic in the vicinity.

I agree that clay is stubborn about changing pH. It is a buffer. In fact, that's the good thing about clay: it attracts and holds ions including mineral ions that plants need. Then if those ions are depleted in the surrounding ground water, the ions seep back out of the clay and become gradually available.
Name: Kamasamudram Ravilochan
Denver, CO (Zone 5a)
kravilochan
May 1, 2017 7:14 PM CST
The alkalinity of the soil was measured by CSU Extension and not at home by litmus paper. So I think that the 8.4 was an accurate number. I suspect I will lose the lilies then because I am not sure they will grow in such alkaline soil.

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Australis
May 1, 2017 7:27 PM CST

Moderator

If you're going to lose them anyway and they've only been in the ground for 3 weeks, then I would carefully dig them up (so as not to damage any new root or stem growth) and either plant them in a better location or in pots where the conditions are more controlled. You might not get blooms this season, but would be less likely to lose them altogether.

@Leftwood, can you advise?
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Name: Kamasamudram Ravilochan
Denver, CO (Zone 5a)
kravilochan
May 5, 2017 7:01 PM CST
Australis said:If you're going to lose them anyway and they've only been in the ground for 3 weeks, then I would carefully dig them up (so as not to damage any new root or stem growth) and either plant them in a better location or in pots where the conditions are more controlled. You might not get blooms this season, but would be less likely to lose them altogether.

@Leftwood, can you advise?


I do see the point you are making Australis. I will strongly consider this. Thanks.

Ravi

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Leftwood
May 5, 2017 9:43 PM CST
I would do as Australis suggests: dig them up and start again. You are not going to be able to change the pH enough (and safely enough) in the short amount of time needed to save your lilies. You are right in that oriental lilies simply cannot survive such a high pH as you have, kravilochan. Relplanting them again will be traumatic for the plants, but I don't see any better alternative.

May I begin by saying that that first wikihow.com link is mostly good, but the recommendation of adding 2 pounds of sulfur per 100 sq. ft. of clay soil to bring a pH 7 down to 4.5 is completely wrong. Yes, the article has a reference, but if you look at that reference, that source absolutely does NOT say that. This is a common problem with wikis in general. People think that if there is a footnote reference, it therefore must be right. Thumbs down Always try to go to a reputable source to get information you can count on. (Please!)

In fact, the reference footnoted (U of Minnesota Extention) does not list a recommendation for clay soil at all. It does recommend that 5.8 pounds of sulfur is needed for silt loam per 100 sq. ft. You will need more than that if your soil is really clay.

The unsourced claim that adding organic matter to clay will raise the pH has some merit if you don't add enough organic matter. An insufficient amount can actually cause more water retention in clay that can raise the pH, but it is doubtful that it would impact a soil that is already as high as pH 8.4. The problem arises when certain ionic compound become overabundant in waterlogged soils. With a heavy clay soil, a sufficient amount would be a 1:1 ratio, organic matter to clay (more is better). As organic matter breaks down, more will be needed. Such a large amount seem incredulous, but honestly, the organic matter seems to just disappear in the clay.

A minor (but understandable) technical mistake is the lumping of sphagnum peat with organic matter as a whole when describing how their pH adjusting works. While it is true that as most organic materials lower pH as they break down, this is not the case with sphagnum. Sphagnum peat is actually more acidic before it breaks down, than after.

In clay soil, there is less of the beneficial soil organism activity than in lighter soils. Remember that since sulfur works through microbial activity, it will work even slower in heavy clay. Sulfuric acid (that comes from the sulfur and lowers the pH of the soil) is mobile in the soil, and will eventually drain through the soil. On the good side, this is less of a problem in clay soil. In addition, with such little rainfall in your Denver area, excess water ought not be a concern.


.
Name: Kamasamudram Ravilochan
Denver, CO (Zone 5a)
kravilochan
May 6, 2017 8:24 AM CST
Leftwood said:I would do as Australis suggests: dig them up and start again. You are not going to be able to change the pH enough (and safely enough) in the short amount of time needed to save your lilies. You are right in that oriental lilies simply cannot survive such a high pH as you have, kravilochan. Relplanting them again will be traumatic for the plants, but I don't see any better alternative.

May I begin by saying that that first wikihow.com link is mostly good, but the recommendation of adding 2 pounds of sulfur per 100 sq. ft. of clay soil to bring a pH 7 down to 4.5 is completely wrong. Yes, the article has a reference, but if you look at that reference, that source absolutely does NOT say that. This is a common problem with wikis in general. People think that if there is a footnote reference, it therefore must be right. Thumbs down Always try to go to a reputable source to get information you can count on. (Please!)

In fact, the reference footnoted (U of Minnesota Extention) does not list a recommendation for clay soil at all. It does recommend that 5.8 pounds of sulfur is needed for silt loam per 100 sq. ft. You will need more than that if your soil is really clay.

The unsourced claim that adding organic matter to clay will raise the pH has some merit if you don't add enough organic matter. An insufficient amount can actually cause more water retention in clay that can raise the pH, but it is doubtful that it would impact a soil that is already as high as pH 8.4. The problem arises when certain ionic compound become overabundant in waterlogged soils. With a heavy clay soil, a sufficient amount would be a 1:1 ratio, organic matter to clay (more is better). As organic matter breaks down, more will be needed. Such a large amount seem incredulous, but honestly, the organic matter seems to just disappear in the clay.

A minor (but understandable) technical mistake is the lumping of sphagnum peat with organic matter as a whole when describing how their pH adjusting works. While it is true that as most organic materials lower pH as they break down, this is not the case with sphagnum. Sphagnum peat is actually more acidic before it breaks down, than after.

In clay soil, there is less of the beneficial soil organism activity than in lighter soils. Remember that since sulfur works through microbial activity, it will work even slower in heavy clay. Sulfuric acid (that comes from the sulfur and lowers the pH of the soil) is mobile in the soil, and will eventually drain through the soil. On the good side, this is less of a problem in clay soil. In addition, with such little rainfall in your Denver area, excess water ought not be a concern.


.


Leftwood, thank you very much for a very thoughtful response.

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