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I read the page on R. rivularis on the PACSOA website and it recommends applying a yearly dose of epsom salt on the palm to help with Magnesium uptake (which keep the leaves green). Has anyone used the salt on a palm? How is it best applied?
just take a few handfuls of the epsom salts and scatter it around the palm like you would when you topdress with fert-around the base of the trunk out some-where the edge of the leaves are. If it is a small palm ( one gallon) then I would only use half a handful.
That sounds like a soil condition to me. Poor drainage does inhibit the uptake of nutrients. It also could be that magnesiums water solubility in high pH soils is poor. As a chemist, this seems likely. Epsom salts both add magnesium and acid in the form of sulfate. Excess magnesium in the soil is bad for the plants so altering acidity with epsom salts makes no sense, but it may ensure the solubility of the magnesium for delivery. Epsom salts may be a quick way to get the palm magnesium, but time release delivery would provide for a consistently adequate level with out worring about adding too much magnesium. For these reasons I add sulfur pellets 2-3 times a year and soil conditioner to improve drainage.
Desertpalm-are you saying that your soil PH is too high, and inhibiting the uptake of magnesium? So you are adding sulfur to lower the PH to make the magnesium already in the soil available to the plant? If so, that is correct-but usually iron is the first micronutrient to show up as defiencent when the PH is too high. The new leaves present as too yellow. I wonder if that is true with palms as with other plants?
I know that in my area, we are lacking in magnesium in the water and the soil, and I add epsom salts to the injector system when I fert the annuals-once or twice a season and add epsom salts to the palms in the ground several times a year. I have talked with various horticulturists (PHd's) about whether the sulfur in the epsom salts is significant enough to lower the PH. The majority don't think so. I haven't seen a difference when I test the PH of the soil. I think the type of fert that you use has more affect -i.e acid or basic fert.
I do think that if you need to add magnesium to soil, epsom salts is the fastest, most effective way. Just as you can use Borax for boran. I actually put sulfuric acid ( 35-40%-battery acid) in the injector system to lower the PH as well as use an acidic fert. Works fast, but you have to do it on a continuing basis. A lot of growers do use Epsom salts though.
Tiger Lilly, my soil pH is around 10, just too high for most palms. I have a doctorate in chemistry and as I recall, magnesium is insoluable or complexed andunavailable in high pH water, so therefore the wet soil has little available magnesium. I agree that epsom will not change the pH of the soil, but the water that you dissolve the epsom salts in will have sufficient pH to keep the mg bioavailability high. That is why epsom salts work fast. The reason you shouldnt use epsom salts too often is that excess mg( as in a concentration spike) in the soil is bad for the plants. Timed release spike do require that the soil pH is not too high to work. To address this issue, I add sulfur pettets which lead to a timed release production of sulfuric acid in small amounts. I prefer the timed release as the risk of acid burn is very low when applied topically. If you have an injection system, it also is probably a low risk unless there is some malfunction in the system.
Holy crap!! Ten??? that is the highest PH I have ever heard of in soil. What is in your soil to raise the PH that high? I would be adding the sulfur pellets as well-they do a good job of bring the PH down and definitely last longer than the sulfuric acid-just takes about a month or so for the microbes to start breaking down the sulfer to sulferic acid. I agree-any excess micronutrient is bad for the plant. I wonder what the PH of your water is? Have you ever tested it? Mine is about 6.3, and after I add the sulferic acid and fert, its about 3-3.5. But like I said-its a short term solution for potted plants.
Interesting to see the differences in the PH of the soils around the country. You (the neighbors) must see a lot of blocked micronutrients in the plants in the ground-does everyone treat the soil like you do?
high clay soils in the west can be pH 10 but are usually 9 or so. Soils back east tend to be more neutral to acidic. My water is city water, that is treated so the pH is modified in the treatment process. Here is an interesting stat: the solubility of magnesium hydroxide in water is 0.0012g/100ml, that is, very low. Since high pH causes mg-> mg(oh)2(insoluble) this means that mg is not going to be bioavailable in higher pH soils as mg-> mg(oh)2. the higher the pH, the lower the apparent bioavialibility of mg, based on it being soluble in water.