Kitchen Garden Forum

Have just dug up my last leeks and was pleased to find that the water retention crystals I dug into the soil in the leek patch last Spring are still there and working effectively, some still entangled in the roots, so they do last a whole season. But I like to grow organically wherever possible so is using them violating my ethics?

I also wondered about this, and have been assured that they are biodegradable and quite O.K. to put on the compost where they decompose eventually, or leave in the ground. I am still trying to find out what they are made of, though.

What are they made of? They don't sound likely to be very organic.

Alan

The crystals are probably coming from the "super absorbent layer" found in most disposable diapers. This layer consists of paper fluff and a chemical absorbent called sodium polyacrylate. Sodium polyacrylate is an amazing water absorber -- it can absorb 200 to 300 times its weight in tap water (even more if the water is distilled) and hold it in a gooey gel.

Sodium polyacrylate is a polymer, meaning that it consists of chains of identical units (monomers). The monomer for sodium polyacrylate is:


--CH2--CH(CO2Na)--
It is a pretty cool polymer -- shake the crystals out of a new diaper (or buy the crystals at a garden center) and add water to them. Pretty amazing!

There is concern in certain circles about the use of sodium polyacrylate next to a child's skin. The concern is often used as an argument against disposable diapers. This diaper page talks about the issue briefly and will give you a sense of what people are concerned about.

These links will help you learn more:

Diaper Polymer
AP Chemistry Polymer Project - polymer experiments
Plant Gel - The other common use for sodium polyacrylate is as a water-retaining gel in houseplants.
Toxic Shock Syndrome and Tampons - The diaper page mentioned above talks about TSS and hints at a relation between TSS and sodium polyacrylate. This page offers a much clearer explanation of TSS.

A sodium polyacrylate superabsorbent polymer made by bulk polymerization and characterized as described herein is a superior gelling agent when provided at a suitable concentration in a gelled anode for an alkaline electrochemical cell. Suitable gelled anodes, alkaline electrochemical cells containing such gelled anodes, and methods for making and using same are also described.
Glad I am not organic I would not put this stuff in my lottie.

Certainly doesn't sound organic
As for "diapers", we used to call them "nappies", they were made of Terry towelling and they were washed - after scraping off the shit . Disposable nappies are a serious environmental threat, so I suppose the crystals fall into the same category.

Alan (old(ish) git, and getting grumpier by the hour )

Oh well, if any of the gel crystals remain entangled in the leek roots after I've eaten them, at least I won't need to wear a nappy to catch the contents when they come out at the other end !!

Dear Primrose, i suppose thats one way of looking at it, that did make me smile.