Question
I am not sure I undersatnd. Are you saying this is toxic? or un-organic? and if it is th e latter, what is it on a scale of 1 to 10?
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The text above is a follow-up to ...

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Where would I obtain Zinc that you refer to? I have not seen that anywhere.
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The text above is a follow-up to ...

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is there some reason i have moss on my roof but not on my lawn? there is just a small amount of moss near a tree, on the north side. but on the roof the whole side is covered with green. i know your not a roofing expert but since its moss can you tell me how to get rid of it? if it was on the grass, what would you do there?
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People wonder how something green can grown and spread on their roof when all the soil is down below.

Thing is, Moss doesn't need soil to grow.  Moss has no roots, so the availability of soil is a nonissue.  New Moss will actually be removed from surfaces during heavy rains, or from scrubbing or brushing.

So, although it may not need soil, it does need water.   Any surface that retains moisture will encourage the growth of Moss.  Moss cannot grown on Metal; smooth surfaces are impossible, which means that metal roofing should be on your shopping list when you sit down in the future to do any roofwork.  Strips of Zinc are sold for this purpose.  You can see a photograph and description of the process at the Oregon State University website (http://bryophytes.science.oregonstate.edu/page24.htm).

You can minimize or control growth of Moss on your roof by decreasing shade and increasing light.  Any tree limbs that shade the roof can be cut back or trimmed to allow as much direct sunlight as possible onto the north side of your roof, where Moss thriving.  Removing dead leaves and pine needles will help light reach surfaces that were previously blocked.  These methods, including the Zinc strips, are also very effective against Moss on decks.
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These are very easy to find.  You can buy them on the internet too.  See Zinc-stop (http://www.z-stop.com/), which sells them in long rolls.

The most popular topical anti-moss products on the market contain zinc sulfate.  These pose all kinds of problems, but the bottom line is that they are anti-Earth and completely unnecessary.

Unnecessary precisely because Zinc Strips are available.  The strips release only very small amounts of Zinc, but inhibit moss growth.  Note, however, they do not remove the Moss - only inhibit its growth.

Answer
OK.  You asked for it.

Zinc is an essential element needed by plants, necessary for growth.  What for?  Zinc is central to regulation of growth and for making chlorophyll and carbohydrates, as well as reactions of enzymes in life processes.

If a plant is deficient in Zinc, symptoms will appear first on younger leaves.  That's because it's hard to move Zinc through stems and branches.  But this is uncommon.

Strangely, farms that grow certain legumes in acreage that was formerly used for Sugarbeets are often deficient in Zinc.  Popular thinking says that the Phosphorous in fertilizer applied to the Sugarbeets crop, plus the high need for Zinc among legumes, is what makes this phenomenon so common.  

Seasons of unusually high rianfall, cooler temperatures and cloudy days early in the season, as well as crops produced on land with poor drainage, are also inclined to be deficient in Zinc

Zinc phosphate is water soluble.  Excessive Phosphorus inhibits the translocation of Zinc within plants and causes deficiency.

But Zinc sulfate is a very common inorganic salt.  It is my understanding that the amount of Zinc in Zinc Sulfate runs between 25 and 36 percent.

Fungicide formulas sometimes include Zinc, but it's too small to cause any problems or even address a deficiency.

Acid soils by the way rarely are linked to Zinc deficiency.  The higher the soil pH, the more Zinc you need.

Too much of a good thing is also possible.  How much is toxic, however, depends on the species of plant being treated because Zinc tolerance varies from species to species.  One Rosarian describes this problem (http://www.gardenguides.com/articles/yellowleaves2.htm) in the Rose Garden: "Although it is rare, too much Zinc can cause symptoms similar to Iron or Magnesium Chlorosis... Tissues turn yellow, then brown. The rib remains green, but the secondary veins lighten. New growth may become stunted and bloom buds may be distorted."  Dosing your plants with too much Milorganite or Houorganite-treated sludge is the best way to induce this condition in Roses, he points out.

So yes, we do have to watch our use of Zinc and Zinc "compounds" in the garden.  They may pass the Organic test.  But you don't want to give too much of ANYTHING.  For your Moss problem, my position is that you have a very good reason to use these, and it will most certainly be solved this way.  Just watch for toxicity and deficieincy symptoms.  Good luck with your Moss.