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absoluteblock

Sulfur application

absoluteblock
10 years ago

I purchased a fifty pound bag of sulfur for our trees that are iron deficient. The soil pH runs about 7.7 or higher around here. The deficient trees include an Avocado and a few ornamentals -- all about ten years old.

The fertilizer people suggested (and my online research corroborates) that it is best to remove a 1-2 foot core, 2 inches in diameter, at numerous locations around the tree's drip line using an auger. Then fill the holes most of the way full with sulfur and water thoroughly in the weeks and months to come.

That's nice in theory but not always possible because of walls, sidewalks, neighbor's property, shrubs, or lawn underneath the drip line perimeter. I'm also a little leery of damaging the Avocado's shallow roots.

How do I get around this problem?

Comments (9)

  • Smivies (Ontario - 5b)
    10 years ago

    I haven't tried it yet but using a grid of the augered holes rather than a perimeter will have better coverage. The instructions I've seen suggest using 1/3 sulfur, 1/3 ferrous sulphate, & 1/3 iron/steel (machine shop shavings, small ball bearings). The ferrous sulphate is the jump start before the sulfur starts working.

  • absoluteblock
    Original Author
    10 years ago

    Unaware of this information previously, I added Ironite to the surface a couple weeks ago and have noticed greener leaves after two thorough waterings. I think my soil has adequate iron, I just need to get the pH down before the Ironite treatment runs out. Hopefully the sulfur will begin to do its thing in 4-8 weeks.

    What about plants and shrubs in the drip line? If I auger near them and apply sulfur, I don't want to shock them with soil that is too acidic if the sulfur is too concentrated. For instance we have some lilies under the edge of the avocado tree and I don't think they can handle anything more acidic than a pH of 6.0.

  • Smivies (Ontario - 5b)
    10 years ago

    Sulfur works slowly...it's not an acid when applied, it becomes sulfuric acid through biological activity. So, you are not going to shock anything.
    The auger holes only have a localized effect, perhaps 6-7" away from the hole. Because of this localized effect, the roots that grow into that zone must have access to excess iron because the ph makes it unavailable to the roots elsewhere. That's why you add the iron into the hole with the sulfur. Ferrous sulfate is only used because it provides iron to the plant immediately rather than waiting for the slower reaction between bacteria, sulfur, and iron.
    I would still suggest that you use a grid under the tree rather than placing the holes around the drip line. You want as may feeder roots as possible to have access to iron in a form that can be taken up.

  • strobiculate
    10 years ago

    to answer the question...no one has explained the concept of broadcast application? Sprinkle over top of ground, water in. Moderately reduced rate compared to drilling core samples, somewhat more frequent applications...and so much faster it's silly.

    And I can question on multiple wisdom the "best" way to apply being to drill holes.

    Broadcast. Simple. Easy. Fast. Allows for more time for beer.

    As for a "cocktail" of sulfur, ferrous sulphate, and machine shop shavings...

    1. The sulfur is the fast acting part of this. The ferrous sulphate must first break down into iron and sulfur, then the sulfur has to be converted to sulfuric acid. The sulfur just breaks down into sulfuric acid.

    2. machine shop shavings? wtf?

  • Smivies (Ontario - 5b)
    10 years ago

    @ strobiculate

    Read up on soil chemistry please...

    "1. The sulfur is the fast acting part of this. The ferrous sulphate must first break down into iron and sulfur, then the sulfur has to be converted to sulfuric acid. The sulfur just breaks down into sulfuric acid. "

    Ferrous sulphate is water soluble, has a natural pH of 2.5, and is the product of iron & sulfuric acid reaction. It is also used for the treatment of chlorosis...not as fast acting as iron chelates but longer lasting. Ferrous sulphate disassociates into iron ions and sulphate ions (sulfuric acid), it does not become iron and sulfur.

    Elemental sulfur requires soil bacteria to convert it to sulfuric acid before having any effect on soil pH.

    "2. machine shop shavings? wtf? "

    Don't wtf me...
    Iron in an acidic environment is oxidized into ions and integrated into soil chemistry in forms that acid loving plants can use. Machine shop shavings offer a cheap way to get iron with lots of surface area (faster reaction). You could use small ball bearings, un-coated nails, etc. instead if you wanted.

  • strobiculate
    10 years ago

    since you want to lecture, here's the subject...

    influence of pH on solubility of polyvalent minerals. feel free to be patronizing and insulting. I won't understand the sarcasm.

    and yeah, without iron, there are no iron ions, but since they are all ions anyway, you win. I took chemistry twenty some years ago, and it didn't stick. my failing. I also was never able to tell the difference on slide samples between xylem and phloem. At a certain point, it's details that don't really matter. And if they do, I'm going to feed you beer. Eventually, it won't. Then we can get down to actually having a conversation rather than insisting on being correct upon esoteric details that do nothing to solve the question at hand.

    and yeah, anyone who espouses the deliberate introduction of sharp metallic objects into the soil is going to get a sharp response. soil + hands + metal/time = annual lockjaw booster. so yeah, wtf? That's the short answer. The long answer is I find such an answer unprofessional, insulting, potentially hazardous, and the kind of old "wisdom" that deserves to die an ignoble death.

    drats! we're talking about chlorosis? if only I had known, then add all the iron you want. Assuming of course we conveniently forget about the presence of other polyvalent minerals that also have similar symptoms to lack of iron. But since I had a hard time with chemistry, I'll let someone else wax intelligent. and then there's that dastardly little thing about iron insolubility. The problem is almost never that there is not any iron present, it's that it is not present in a form that is soluble to plants. So addition of metal to a soil to correct lack of iron is at best redundant or solves a problem that simply does not exist, and potentially creates more.

    All of which does NOTHING to answer the original question. I happen to have better things to do with my time that to dig/drill core samples on a grid through the dripline or root zone of a tree, and that's assuming a isometric plane where everything is always the perfect condition. So how do you do this in an easier fashion, or deal with real world circumstances dictated by lot lines, driveways, and other existing conditions, such as retaining walls, fences, neighbors the devil has banned from Hades, swimming pools, parking lots, and patios, to name a few.

  • danbonsai
    10 years ago

    strobiculate wins!!! But you both have great minds. On a good day, if you both worked together , you could solve some very complex problems. Bottom line is , too many
    site issues to solve absoluteblocks problem.....
    strob, I agree, Millertime......

  • absoluteblock
    Original Author
    10 years ago

    Sort of ironic that strobiculate says he has better things to do with his time but blithers on for several paragraphs to insult another poster in this thread. In any case...

    I asked this question because the magnitude of the soil pH problem in the Avocado tree has severe consequences. Iron deficiency becomes most apparent during January and February when the days are short. If you work long days or travel for long periods, you may not notice how awfully yellow the leaves have become in short time. Without quick intervention, the Avocado tree drops 100% of its leaves and grows new ones in the spring, severely impacting the yield that year. You might go from 300 avocados the previous year to 25 in the current year if this happens.

    I'm like you, I have better things to do with my time than frequently apply iron or sulfur or watch the leaves on a regular basis for signs of yellowing. I would much rather apply the sulfur in such a way that it lasts a year or two or three...

  • wisconsitom
    10 years ago

    Abso, I have treated chlorotic maples with soil sulphur. I broadcast on soil surface and replaced wood chip mulch over the top of that. I'm sure I also placed sulphur right on top of mulch a few times. It worked. The key seems to be to broadcast over a sufficiently wide area. I don't have a formula for this, but tree's dripline is a good start.

    I come down on the side that says that where iron is present, but due to a too-high soil pH, unavailable to a plant species, the best solution is to change that pH. FWIW, in my area, manganese is also limited, for the same maple species (rubrum), and is corrected via the same treatment.

    In the background of all of this though is the realization that the long-term solution is to not try to grow plants unsuited to the local soil chemistry. This may or may not apply to your avocados-I certainly have no experience with them, but long ago became my primary focus with our red maple problem. Then, freemanii maples became all the rage-for good reason-and we don't worry about something so silly anymore. Again, not saying your situation is silly. Ours was! It was kind of fun though, turning those trees' leaf color around. Some river birch also received and benefitted from the same thing. But they're not native where I live, while the excellent paper birch is. And guess what? Paper birch showed no inclination towards chlorosis, ever.

    +oM