Rubber tire mulch as a zinc fertilizer under tropical fruit trees?

[chrobrego]

Anyone have any experience using rubber mulch around the base of their fruit trees as a slow release zinc fertilizer?  I put a bunch of rubber tire mulch around my trees about ten years ago because I was lazy having to remulch with cypress. I then read recently that rubber does break down in the environment despite the claims from the Vigaro rubber mulch bag. The leachates are rendered nontoxic during the rotting process (I read the research done on children's playgrounds), but some heavy metals are released, namely zinc with some trace aluminum. I'm not worried about lead as car tires typically don't have much and lead isn't taken up into fruit tree tissues anyway. The main warnings online from garden people are about zinc toxicity, but nobody provides any evidence.  I did see some evidence from a soil test on a playground that had tire mulch that was 15 years old and piled 4 inches high.  The soil tested at 20ppm while toxicity usually occurs around 200ppm.   The amount of zinc leaching also slows down as the tire is broken down in the environment.

Anyway, I read a study done in India that suggested using tire crumb as a low cost slow release zinc fertilizer for tropical fruit trees -- namely because high PH sandy soils are usually deficient in zinc. In fact, the leaves on my tropical fruit trees couldn't be any bigger or greener.

I'm in the process of deciding whether to remove the tire crumb mulch or keep it.  What would you do?

[CarolinaZone]

Tires as mulch? Say it ain't so.

[Galatians522]

Might be useful for things that are typically defficient in Zinc like Pecans.

[Seanny]

Tires as mulch? Say it ain't so.

Anything that block water vapor from the soil from escaping is a mulch.
Rocks and pavers and other chunky materials are mulches.

[Bush2Beach]

That is toxic slow release

[Daintree]

I looked at the colored rubber bark chip mulch for my greenhouse, but didn't care for the fumes it released. Also, my parrots are like puppies and put everything in their mouths.
Aren't they doing some toxicity research on the crumb rubber they put in artificial turf?

Interesting!

[850FL]

What form of zinc? There are forms of 'good' minerals that can be toxic. And what about other chemicals and compounds it would release?

[FigoVelo]

It doesn’t seem like a great thing for the garden. Tire rubber releases a chemical called 6PPD-quinone that kills coho salmon almost instantly and at incredibly low concentrations. Seems reasonable to assume until proven otherwise that tire rubber is not good for trees and soil ecology. Is it so important to give trees zinc?

[850FL]

One example, zinc phosphide a mole killer, toxic to mammals including humans. Yet we and plants need zinc and phosphorous in other forms. I never ever put rubber mulch or that dyed crap around edibles.

[roblack]

Much better sources of zinc without all the excess crap in rubber. One of the reasons to grow your own is to avoid contaminants.

[thesimsdude]

This sounds like a horrible idea

[cassowary]

Anyone have any experience using rubber mulch around the base of their fruit trees as a slow release zinc fertilizer?  I put a bunch of rubber tire mulch around my trees about ten years ago because I was lazy having to remulch with cypress. I then read recently that rubber does break down in the environment despite the claims from the Vigaro rubber mulch bag. The leachates are rendered nontoxic during the rotting process (I read the research done on children's playgrounds), but some heavy metals are released, namely zinc with some trace aluminum. I'm not worried about lead as car tires typically don't have much and lead isn't taken up into fruit tree tissues anyway. The main warnings online from garden people are about zinc toxicity, but nobody provides any evidence.  I did see some evidence from a soil test on a playground that had tire mulch that was 15 years old and piled 4 inches high.  The soil tested at 20ppm while toxicity usually occurs around 200ppm.   The amount of zinc leaching also slows down as the tire is broken down in the environment.

Anyway, I read a study done in India that suggested using tire crumb as a low cost slow release zinc fertilizer for tropical fruit trees -- namely because high PH sandy soils are usually deficient in zinc. In fact, the leaves on my tropical fruit trees couldn't be any bigger or greener.

I'm in the process of deciding whether to remove the tire crumb mulch or keep it.  What would you do?

red topical ants eat rubber, they actually search it out so can't be that bad. There's plenty of old 40 year old tires around our property and those have not affected the tree's in a negative way.
And I wouldn't be worried about zinc toxicity in produce, Zinc sulphate heptahydrate is a common amendment.
Rubber tires are in general 50% natural rubber so not to bad actually. The reinforcement is probably galvanized steel and that's where you get the zinc oxide from.


 

[pagnr]

Intact tyres probably degrade more slowly than tyre mulch which has more exposed surface area.
I think you would get more benefit from higher quality Zinc amendments and also degradation of natural wood mulch which should add beneficial microbes and humus.

[1rainman]

Given enough time and exposure to elements anything will rot including plastic and eventually cycle back into basic elements. But they put so much toxic chemicals into making rubbers or plastics. It probably won't kill you but probably not the best thing to be exposed to as far as edible plants.

I just occasionally crush up a multi vitamin mixed with water and fertilizer. All the micronutrients a human uses is the same for a plant. But also compost wood mulch etc usually has the nutrients needed. As well human urine is a free fertilizer mixed with water it's almost the same as actual fertilizer most of which use urea as a nitrogen source but would have micro nutrients that you are consuming. Though buying sewage fertilizer is not good because of the contaminants in it.