Magnesium

This question was raised about soil magnesium levels:

"Would there be any benefit of adding chelated Mg in a popup with 10-34-0 and zinc? Soil test levels of Mg are 150 with base saturation of 4 to 8%. Was thinking of this or broadcasting Kmag.:  

I would agree those levels are low and some magnesium might be beneficial.  I have used dolomitic pellet lime to provide a little magnesium but not KMag.  I had good results with pellet lime but my magnesium levels are rarely low and not as low as those in the post.   Here was my reply which expands away from the question.  I thought it was interesting.   ""What Do The Weeds Really Tell Us?

"Weeds shouldn't be a plague or a market(plant?) to eradicate. They should be viewed as what they are meant to be, an indicator of your soil conditions. Weeds can tell you more about your soil fertility than most standard soil analysis, if you know how to read them. Thes e unwanted guests have many benefits, foremost is to rearrange the soil to allow other plant and soil microbial life to repopulate and restore nature's balance.

Low calcium levels tend to favor many weed types, mostly the grasses like foxtail and quackgrass. Broadleaf weeds are an indicator of a phosphorous to potassium imbalance. They also act as a detoxifier of chemicals in the soil. Theoretically, the more toxic chemicals you apply, the more broadleaf weeds you will be favoring. Succulents are an indicator of poor drainage (anaerobic conditions) and low carbonate ions.

Certain weeds obtain specific nutrients from the soil at various depths . And in various circumstances, e.g., compacted soil, water logged soil, chemically contaminated soil, and high-salt soil. In turn, they manufacture certain metabolites, which they excrete into the soil rhizosphere to be processed by specific microbes. Likewise, these microbes uniquely obtain and metabolize certain nutrients from the soil, which they, in turn, alter and re-excrete into the rhizosphere for use by plants and other microbes. Left to operate naturally, this process regenerates a "sterile" or "toxic" soil to the point where the plant and microbe populations change again and again, eventually to support whatever crop and microbe group we desire. An organism will survive and thrive only if the proper conditions have been established for it to do so. (From Science in Agriculture, Arden Andersen).

Calcium & Magnesium
An imbalance of magnesium to calcium can lead to tight soils and anaerobic conditions. Calcium causes soil particles to move apart and provides good drainage and oxygen movement. Magnesium allows soil particles to stick together, limiting oxygen, which does not permit beneficial microorganisms to flourish. This does not allow organic matter to decompose properly and promotes fermentation that favors by products like alcohol and formaldehyde. These conditions also favor soil diseases such as pythium and phytophora. An ideal Ca:Mg ratio would be 7:1. Weeds that indicate a Ca:Mg imbalance leading to a tight and poorly drained soil would be: Creeping buttercup, curled dock, giant sorrel, broad-leaved meadowsweet, field bindweed, and quackgrass.

Phosphorous and Potassium
Phosphorous is important to the manufacture of sugars and is a key factor in the transport and translocation of nutrients and metabolites within the plant. Too much potassium will have a tendency to replace calcium in the cell resulting in weak cells and black spots on the leaves. An improper phosphorous (P) to potassium (K) ratio will favor the broadleaf weeds like: ragweed, eastern bracken, yarrow, velvet leaf, and lamb's quarter. A proper P:K ratio is 2:1 for most row crops and 4:1 for alfalfa and grasses. "

Excess Magnesium does lead to to tight soils and anerobic conditions.  That is a major symptom of crop production in southern Ohio and most places I travel.  The addition of calcitic ag lime and gypsum has slowly taken these symptoms away where applied, sometimes quickly, usually slowly.

Dr. George suggested magnesium for some of my ailments.  I told him that was funny, I took dolomite for years at Rhude Road to address the same symptoms.  Limestone is absorbed poorly by single stomach animals though like pigs and humans and now there is a much better way to supplement Magnesium.

I noticed brown limestone is coming out of the quarry on Stone Road northeast of me.  I have not spread much brown lime but have used brown limestone gravel.  It is a different analysis.

Does your soil need mangesium?  Probably not, mine doesn't.  Does your body need magnesium?  Possibly so, there is limited magnesium in most diets.

Ed