This is a direct quote from an acquaintance of mine. He is the principal in the marketing of a product called "Fertisorb", which is a polymer product that already contains various fertilizers. He's also marketing a 12" container kit. The container is made from rice hulls, bamboo, and corn husks and it comes complete with Fertisorb incorporated into the soil (coir) pellets, so all you do is hydrate and plant. BTW - The fertilizer analysis in the Fertisorb is N: 1.1% (.495% ammoniacal & .605 nitrate N), P: .4 and K: .8, which is almost exactly a 3:1:2 ratio and is guaranteed to be adequate for 4 months.

The quote:

"Polymers will allow you to extend the time between waterings, but are not a substitute for regular waterings. You may get an extra day or possibly 2 between waterings, not 2 weeks. They have such greater absorptive capacity than your surrounding media that they will compete for and absorb water from the surrounding media, and can actually dry out the media itself. You need to keep your media regularly hydrated, not only for the plant's sake, but for the sake of the media as well. Also, since straight polymer (not polymer into which fertilizer has been incorporated) swells up so much when hydrated, you should hydrate the polymer before mixing it in your media, otherwise it will push the plants out of the container. After mixing, give the media itself a good watering to equalize the moisture between the polymer and the media".

Al

Thanks, Al.

Anybody else with something to share regarding this material?

My dad throws a few dashes into the holes he digs when he's planting around the yard.
Most of the time it's buried and no one ever sees it. I've begun incorporating it
into container soils for ferns.

Josh

Their have been many water holding polymers over the years. They all take up a lot of water, but the companies rarely reveal how much the plant has access to (keep in mind some of these same products are used in diapers that dont leak??). Some of the newer, corn starch based products are less prone to causing problems and have your plants lifting out of the containers (which WILL/CAN happen). I dont know if they have ever been shown to directly influence/contribute too water molds (root rot as an example), but it is worth thinking about. The other items Al passed along sound very accurate in my mind.

Schmoo

Hi,

I would be very careful before I used that. I do not use them as I've read the water crystals can actually "steal" (absorb) water from soil when they are dry and steal nutrients too...

Heres are a few quotes from the PDF I attached to this post. The PDF was written by Washington State extension educator and scientist, Linda Chalker-Scott. The title of the PDF is "Super-absorbent water crystals are they really so super?":

Quote 1:
"Moreover, excessive use of PAM can lead to nutrient deficiencies; phosphate and silicon were reduced in tomato and wheat, and this latter plant also suffered manganese and boron deficiencies when grown in under high PAM concentrations."

Quote 2:
"Summary and recommendations:

Many of the products labeled "water gel crystals" and "poly-clear" are cationic PAM gels. Not only are they are more toxic to aquatic organisms and generally less effective than anionic gels in landscape situations, they can also contain higher levels of residual acrylamide. Even though these cationic gels are banned for many applications, they are still manufactured and sold in the United States, China, and other countries. Cationic PAM hydrogels should not be used in gardens and landscapes.

It is difficult to predict short-term effectiveness of anionic PAM hydrogels on plant survival and establishment, since the ability to absorb water is reduced by several environmental factors, especially salt, temperature extremes, ultraviolet radiation, and microbial activity. The functional lifespan of cross-linked PAM hydrogels used outdoors can be as short as 18 months and at best only a few years; they cannot be regarded as long-term solutions to landscape water needs."

Quote 3:
"Even if gels are protected from environmental exposure they will still be broken down by decomposition. A number of naturally occurring soil microbes have been identified as active decomposers of both soluble and cross-linked polyacrylamide gels. Decomposers include bacterial species (Bacillus sphaericus and Acinetobacter spp.) and white rot fungi (Dichomitus squalens, Phanerochaete chrysosporium, and Pleurotus ostreatus). The fungal species solubilize the polymer, which is then susceptible to further degradation by many other soil microbes.

ItÂs not surprising that polyacrylamide is rapidly broken down by decomposers; one study found the average size of the polymer to be less than 25% of the original in only 14 days of microbial action. These gels contain a significant amount of nitrogen, which is often a limiting nutrient in both aerobic and anaerobic environments."

Quote 4: (a quote from the "Idaho Gardener")
"Basically, hydrogels also called polymers, or water saving crystals, are a big no no and if they arenÂt they should be. Contrary to popular belief, they do not make the water they absorb available to the plants which need the water, and worst of all, when they decompose they become nasty little toxic, hazardous pollutants in the garden and on the planet. Can you say "ICKY Yuck!?""

HTH :-)

Hi,

here is another PDF which I think you'll find useful.

Seems to me growing a plant only in this material would be a perfect test would it not?

http://www.watercrystals.com/soillessplants.htm

I may try this myself. Some means of fertilizing will be needed naturally.

solanaceae,

No, it would not be perfect test a myriad of reasons listed in my previous two posts. And do to the fact hydrogels have been tested to death by scientists. Here a few problems with hydrogels:

air porosity issues
nutrient uptake issues
decomposition issues
etc, etc, etc
While some people use it as an amendment and fewer use it as the sole substrate. I would suggest not using it at all...