How can I lower Magnesium Level?

Discussion in 'Pesticide & Herbicide Application' started by WiseGrass, Apr 30, 2009.

  1. WiseGrass

    WiseGrass LawnSite Member
    Messages: 4

    Does Solu-Cal S effectively lower my magnesium level? Can I go higher then the 12lb per thousand corrective rate 2x annually?

    And would Solu-Cal help release of the dog pee problems behind decks etc.
  2. lilmarvin4064

    lilmarvin4064 LawnSite Senior Member
    Messages: 757

    how do you know you have high mag? I assume you have a soil test done? What is the base saturation % of the Ca and the Mg? What is your pH?

    Solu-cal S will help, but might not be the best product. What is your sq. ft.?

    Your might be better off with regular gypsum (calcium sulfate) or calcitic lime if your pH is low.

    The Solu-cal S will increase the likelyhood of uptake of calcium into the grass, from what I hear.
  3. lilmarvin4064

    lilmarvin4064 LawnSite Senior Member
    Messages: 757

    1 bag of solu-cal S is like a a 6-month fix as compared to 4 bags of gypsum with a "3 months-from now to 12 month fix." Basically, what you need is calcium, and lots of it.

    The smaller the particle, the faster it works (and disappears), add some polyhydroxycarboxylic acid and you're set! :drinkup:
  4. ant

    ant LawnSite Silver Member
    Messages: 2,469

    what is your soil Ph? Low soil pH decreases Mg availability
  5. Think Green

    Think Green LawnSite Silver Member
    Messages: 2,746

    Not much help from the lack of information, but maybe this will help!

    It's still a little-known fact that the Calcium to Magnesium ratio determines how tight or loose a soil is. The more Calcium a soil has, the looser it is; the more Magnesium, the tighter it is, up to a point. Other things being equal, a high Calcium soil will have more oxygen, drain more freely, and support more aerobic breakdown of organic matter, while a high Magnesium soil will have less oxygen, tend to drain slowly, and organic matter will break down poorly if at all. In a soil with Magnesium higher than Calcium, organic matter may ferment and produce alcohol and even formaldehyde, both of which are preservatives. If you till up last years cornstalks and they are still shiny and green, you likely have a soil with an inverted Calcium/Magnesium ratio. On the other hand, if you get the Calcium level too high, the soil will lose all its beneficial granulation and structure and the too-high Calcium will interfere with the availability of other nutrients. If you get them just right for your particular soil, you can drive over the garden and not have a problem with soil compaction.

    Because Calcium tends to loosen soil and Magnesium tightens it, in a heavy clay soil you may want 70% Calcium and 10% Magnesium; in a loose sandy soil 60% Ca and 20% Mg might be better because it will tighten up the soil and improve water retention. If together they add to 80%, with about 4% Potassium and 1-3% Sodium, that leaves 12-15% of the exchange capacity free for other elements, and an interesting thing happens. 4 or 5% of that CEC will be filled with other bases such as Copper and Zinc, Iron and Manganese, and the remainder will be occupied by exchangeable Hydrogen , H+. The pH of the soil will automatically stabilize at around 6.4 , which is the "perfect soil pH" not only for organic/biological agriculture, but is also the ideal pH of sap in a healthy plant, and the pH of saliva and urine in a healthy human.
  6. greendoctor

    greendoctor LawnSite Fanatic
    Messages: 10,136

    I have dealt with out of whack soils where the calcium/magnesium levels are inverted. This is a common problem in Hawaii. Characteristic of those soils is a total lack of drainage and growth of algae on the surface. Another clue is how well palms grow in comparison to the rest of the landscape plants. Palms have a high need for Mg to stay green. My fertilizer program on those soils involves supplying most of the N with calcium nitrate. The remainder comes from potassium nitrate. These are also soils that benefit from application of elemental sulfur to adjust the pH down.
  7. WiseGrass

    WiseGrass LawnSite Member
    Messages: 4

    GreenDoctor thanks! the problem area has a drainage issue, 1% drop in about 50feet and partly shaded. pH is 6.8

    For now I am leaning toward the SoluCal S route. 12lbs per 1,000 twice this year yet, Retest in September to see the progression. Hopefully we can grow out of it.

    Soil test
    CEC13.4 Acidity2 soilpH6.7 bufferpH6.35 %OM5.8
    Lbs/A %Saturation Potassium332(3.2%) Magnesium808(25.1%) Calcium3044(56.8%)
    ppm K166 Mg404 Ca1522 P83
    lbs/A P205 381 K20 398 MgO 1292
  8. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,335

    Have you asked yourself where the Mg is coming from?
  9. greendoctor

    greendoctor LawnSite Fanatic
    Messages: 10,136

    Solu-Cal will raise pH. I deal with soils that are high pH and have excess magnesium. Liming materials are avoided in that situation. Calcium nitrate or calcium sulfate(gypsum) will add calcium and not make the soil more alkaline. 6.8 is right at the edge where micronutrients become less available.
  10. lilmarvin4064

    lilmarvin4064 LawnSite Senior Member
    Messages: 757

    ha ha, what do you mean? This is common in many areas. like mine!

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