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Eastern Pennsylvania

To raise my Mg level from 225 to 500 ppm, how much epsom salt should I add per 1000 sq. feet? Thanks in advance -Jim

4/12/2008 11:20:18 PM

Kevinstinindians@yahoo.com

You can't do it Jim. Epsom salt is usually only 10% Mg. You'd have to apply 125 lbs/1000 sqft, if my math is correct. The most you should add at one time is about 10 lbs/1000. Keep in mind it will also lower the pH of your soil a little.

If you need to raise the pH I'd go with Mg Lime, aka dolomite. I'd find the highest percent Mg lime you can. The Mg %'s in dolomite can range from 4% up to 23%. You could easily correct an imbalance with 23% Mg. If you don't need the pH adjustment I'd keep this in mind for next season as an option.

Why do you need to raise the Mg so high? I'm guessing your K level is high. If thats the case I wouldn't worry about it too much. If you don't need a pH adjustment I'd add 10lbs epsom salts/1000 for this season then retest in the fall.

4/13/2008 10:36:28 AM

Paradise Mountain, New York

I always thought your Magnesium was expose to be 1 1/2 times that of your potassium to keep your soil balance

4/13/2008 11:07:27 AM

Mill Bay, British Columbia

Jim, I added 8 lbs. Epsom Salts to roughly 1000 sq ft in the fall and it raised my Mg from 146 ppm to 191 ppm (about a 30% raise). I then added another 8 lbs this Spring, let the rain work it in and then re-tested to find that the level had again raised to 245 ppm (again about a 30% change). My PH remained the same at 6.9

4/13/2008 11:45:35 AM

Picton,ON (j.vincent@xplornet.ca)

The thoughts on Magnesium are that the ppm level should be at least equal (1:1 ratio) to the potassium. This goes back to the old perfect balances soil theory and may not really apply when out potassium level reach very high to excessive levels. Many of the University extension folks believe that although potassium and calcium may compete with magnesium for uptake, the ratio thing doesn’t apply once we get the mg over 100-150 ppm.

However, I have continued to add magnesium to my patch to try to attain this ratio. Keep in mind as you add manure you will increase your potassium, but you will also increase your magnesium.

The best product to use for this is potassium magnesium sulfate, aka sulfate of potash magnesia, k-mag, aka sul-po-mag. The material comes from New Mexico and has an analysis of 0-0-20-10mg-20S (some grades are slightly higher). The potassium is in the sulfate form as is highly available. Most ag fertilizer dealers will have the product if you are in a low magnesium area. It is not expensive. I add about 10 lbs / 1000 ft2 every year

4/13/2008 12:08:57 PM

Kevinstinindians@yahoo.com

Glenn, how deep do you till the soil?

4/13/2008 1:40:05 PM

Eastern Pennsylvania

Thanks all, yes I have high K levels. My yard was an old farm and they were high to begin with when I started. K = 295, Mg = 225, Ca = 3400. % saturation K = 3.8, Mg = 9.5, Ca = 86.3. The lab suggests that my Mg is "very low." Is this not really a problem? My pH is 7.3 so I don't really want to use lime this season. Thanks again -Jim

4/14/2008 10:24:26 PM

Kevinstinindians@yahoo.com

I'd add a maximum of 10 lbs of epsom salts/1000 sqft. I really don't think you're going to see any problems.

4/15/2008 12:39:36 AM

Mill Bay, British Columbia

Kevin, I till it in 6-8".

4/15/2008 7:05:21 PM

Utah

why don't we add more than 10 lbs of epsom salts/1000 sqft?

4/15/2008 7:27:32 PM