What are they made of? Nancy

They're mostly water and supposedly "non-toxic". The additives are to keep the water from freezing hard. They can have an added acrylic, broken down cellulose, or even silica gel. A few years ago California forced a recall of packs with diethylene glycol and/or ethylene glycol added. That's the stuff in automotive antifreeze, a poison. Dunno if they're still made.

Wanna take a chance?

I would not put that stuff in the compost. Cellulose or silica are quite natural, but the plastic polymers are not.

Silica, as in the little packets that you get in packages that say "DO NOT EAT"?

Even if it were not dangerous to compost them, I doubt they would make good compost?

Well, there is that. Sometimes it's a matter of landfill diversion rather than the goal of making compost. For example the cellulose packing peanuts are better thrown in the compost than the landfill, but they are not exactly sought after as a premium compost ingredient. :-]

I would expect that this gel could be used as an underlying water source in drought conditions when planting out tube stock trees.

The gel is USELESS as a water retentive compound. So is the stuff from disposable diapers.

They probably are not compostable.

Sorry but that statement is a little odd. Why do they place these crystals in nappies? I believe its to retain the water (urine). I place it in the planting hole, put soil over it then plant the tube stock and water in. No negative effects here.

It HOLDs water, it doesn't give it up when the plants need it.

Is that borne out by some kind of testing? Not that I'm in favor of adding synthetic water holding gels to soil - I've never liked the idea and prefer compost. But even natural materials like clay have a very high - oh what's the hydrogeological term for the suction required to drain pores? It's like 1000 times higher for clay than sand. And yet things will grow in clay and somehow extract water.

One would think, if these water holding gels didn't work in side by side tests, there would be little reason to bother adding them to potting mix...

So are you saying that the plant would not seek out the moisture? I couldn't see roots avoiding this moisture.

Think the contents of these ice packs could be used as fertilizer on my ornamentals and edibles? Thx.

Usually they are made from sodium polyacrylate.

Sodium polyacrylate is a super absorbant polymer (expands up to 300x when saturated with water) is considered non-toxic (used unsaturated as an adsorbent in nappys), and being a polymer like plastic, is relatively stable/inert (generally not biodegradable, but can break down under direct sunlight).

There seems to be conflicting reports as to exactly how quickly it decomposes.

A very similar material (potassium polyacrylate) is I think already in common use in the agricultural industry, and there is research being conducted into its use for the purpose of improving soil water retention in sandy soils to alleviate desertification.

It holds and slowly releases not just water but also nutrients and pesticides. In the industry, I think it is usually in the form of large crystals as opposed to a hydrated gel like in an ice pack.

Some people say that it is great at absorbing water but not at releasing it, but this shouldn't be the case. From my limited chemical understanding, the closer it is to being fully saturated, the easier it should be to pull that water out.

There is a chance of too much salt (due to the sodium) being released into your compost if it does degrade.

Some people also imply that if it doesn't degrade then it's bad. Generally thats true (burying plastic in your garden is usually frowned upon). But my thinking is that if it doesn't degrade, and if it doesn't get absorbed by the plants, then thats perfect because it is a permament, basically inert soil improver.

So in my opinion, it should be fine.

That's just my two cents. I'm not a horticultualist, biochemist, or chemical health expert, so don't take my word for it and make your own judgement.

As an added note, I would not recommend using the unsaturated material in the compost. Worms will eat it as they burrow, and it will adsorb body fluids and expand in their bodies. The pre-hydrated gel shouldn't harm them though.

I am a chemist, and I have some experience in chemical toxicity, for what it's worth.

There seem to be some potentially good properties to this stuff. However, I would want to see some controlled studies that clearly indicate that it does not have detrimental effects on plants or soil biology, before I would put it in my soil. With an understanding of its physical properties we can guess at how it will behave in soil, but the biological end and the long term effects on soil health is something that has to be studied before we know it's safe. Not all things that are 'non toxic' are necessarily healthy. Just my two cents.

I - for one - want to hear more from you. Can we use this as a soil/ plant adjunct (with NO harmful effects); can this be added to soils/ plants early in a season and (for those in the South) could be a water-retaining/ water-releasing compound (during HOT summer months). I... am prolly 'naive', but I'm having trouble believing we've invented and are distributing this 'thing' and have NO idea 'what happens to it next.' I've got DOZENS of these these gel-packs stacked up; what do I RESPONSIBLY do with them?

Chad, I've been saving some for the past couple of years because the claim says they can be used for plant food. I figured I'd get all the info I could on the stuff before I put it in my garden. The things i'm coming across don't seem to give any real clear and positive answers as to whether it's good for garden plants. Seeing that they say it's safe for plumbing I'm washing mine down the drain. I don't think I would if I had a septic system, but I'm on a city sewer system, so I'm sending in down their way. If they don't like that they can go after the ice pack companies.

For what it’s worth, there’s a University Extension program that explains “a few .. tests are useful for back-yard composters [that] helps composters understand the many criteria involved in assessing ((( compost maturity ))) from pH to microbial activity to temperature.” I understand that what we are discussing in this article is different. However, understanding the properties of gel-pack contents and their impacts on plants can probably be tested in a similar manner. We many not be able to *directly* find out the properties of the gels, but we can *directly* observe the impacts that its (hidden) properties have on plant growth and germination.

If you’re interested follow this link: http://sfyl.ifas.ufl.edu/sarasota/natural-resources/waste-reduction/composting/what-is-composting/when-is-compost-ready/compost-maturity-test/

or type something like this into google: Compost Maturity Tests plant growth and germination

Incase the article ‘disappears’ (dreaded 404 code!!) I’ll do my best to give a rundown of the type of procedure that can be used:

PLANT GERMINATION TEST

Performing the Test

1. Put 1/4 cup of ((( the test agent eg: gel )) in the paper cup
2. Add the 1/2-cup of clean water (( perhaps consider using bottled water ))
3. Mix
4. After two hours, filter the mix through cheese cloth and collect the liquid (called filtrate)
5. Prepare six glasses by putting a piece of tissue or paper towel at the bottom of the glass and adding five seeds to each glass (( consider using radish seeds if you can easily get them as they germinate quickly ))
6. Place about 20 drops of clean water on the paper in each of three glasses (this will be your control, to see if there is a problem with your seeds or your testing agent), seal the glasses with aluminum foil and tape, and then label the dishes "control";
7. Place about 20 drops of testing agent filtrate on the paper in each of the other three glasses, seal the glasses with aluminum foil and tape, and then label the dishes “gel filtrate“ and
8. Keep the glasses in a dark place at room temperature (around 80 degrees F, or 27 degrees C), and then observe and record germination after 24, 48, and 72 hours using.

PLANT GROWTH TEST

This test helps to see if the test agent provides nutrients to plants or, potentially, robs nutrients from plants or even ‘poisons’ them.

To complete this test, you will need the containers and seedlings started in the ‘plant germination’ test. Note: these seedlings will be y days old.

Performing the Test

. Trim samples to leave just three seedlings per container

. pot seedlings up in a straight gel mix or a potting medium + gel mix … ensure all mix amounts are measured to ensure each mix is the same

. Irrigate regularly to keep containers moist (( using a spray bottle allows a roughly controlled amount .. eg 3 full sprays each )))

. You may fertilize once, if you want, but fertilize no more than half each of the compost and control containers, taking care to add the same amount of fertilizer to each container (( perhaps add liquid fertiliser to watering spray bottle));

. After 21 days, harvest the crop from each container, wash the roots to remove gel / gel + potting medium mix, weigh the sample, and record the data from each container separately;

. Calculate the average weight per plant for the fertilized versus the unfertilized plants in each media type; and

. Arrange/rearrange your containers to set up a new random pattern of control and compost containers, and repeat this step every seven days.

Hopes this is of use to someone out there!

Best of luck, and remember: SHARING (your results if you do these tests) is CARING!! ; )

I'd like to qualify my previous answer about this stuff. Jonathan Travatt posted:

"A very similar material (potassium polyacrylate) is I think already in common use in the agricultural industry, and there is research being conducted into its use for the purpose of improving soil water retention in sandy soils to alleviate desertification."

There is little to no functional difference between sodium and potassium here. I suspect the version used in ag has K instead of Na because K is a plant nutrient whereas excess Na is no good and potentially detrimental. Easy enough to make the K form so why not.

I would have no problem putting, say, used potting soil containing PVA in my compost bin, so probably a moderate amount of it in the compost is no big deal. Of course it's all a matter of dose, isn't it? I'd be more worried about it building up in soil to the point it noticeably changes the texture, than I would be about toxicity to plants or humans.

ive used them in my flower gardens with no ill effects.