The potential toxicity of hydrogels is not something that a botanist
would have the expertise to answer. The company Download page has a
Material Safety Data Sheet (MSDS) which lists some toxicity tests on
fish and bacteria. The chief hazard would seem to be possible
inhalation of dust during handling. That can be avoided with proper
equipment. Any toxicity would be much more likely to affect the
factory workers or workers who apply the material to the soil than
consumers of crops produced in hydrogel amended soil.

The bigger question is whether the material is effective and cost-
effective. The company webpage on History shows three photos of a
field supposedly improved by hydrogels. However, there are no photos
of a control field that received no hydrogels. Thus, there is no way a
scientist can judge the effect of the hydrogels. There are also no
numerical data indicating the percent increase in biomass with
hydrogel compared to no hydrogel.

From a scientist's perspective the company website is very vague. It
says the product significantly improves plant growth and soil water
content but provides no numbers, i.e. is it 1% or 10%? Does the yield
increase pay for the cost of the hydrogel?

It strikes me as odd that if the product is so effective for
subsistence agriculture in arid areas, why is the website only
marketing it to for mainly aesthetic uses such as sports turf,
landscaping, horticulture and home and garden.

The site has a section for press clippings, although none are listed
there. Where are peer-reviewed scientific articles evaluating the
product?

Potassium hydrogels also act as a potassium fertilizer so the control
treatment must also supply the same amount of potassium. Was this
done? This product also contains substantial amount of "NPK
fertilizers and trace elements." Are the effects mainly due to the
fertilizer or the water absorbent properties?

The claim that this is a proprietary mixture of polymers begs the
question of how many combinations were field tested before coming up
with the ideal mixture and how much more effective is the mixture
compared to existing single hydrogels?

I know of a research study that evaluated a hydrogel used in container
growing media. The study found that for about the same cost, organic
matter could provide the same amount of increased water holding
capacity as the hydrogel.

There are other low tech methods of conserving soil moisture such as
mulching, adding organic matter to soil and fallowing fields between
crops. Is hydrogel more cost-effective than these techniques?

Google scholar can be used to locate scientific articles on hydrogel
effects on soils.
http://scholar.google.com/scholar?hl...il&btnG=Search

David R. Hershey, Ph.D.
http://www.angelfire.com/ab6/hershey/bio.htm















On Nov 17, 11:55 am, "fedrik de beul" wrote:
Hello,

I am journalist studying the question of the use of polymers in soil
conditioners such as Terracottem.

The company (seewww.terracottem.com) says it is non-toxic, but is that
really so? How sure can we be?

Other question : this soil conditioner is highly expensive, supposedly so
because of the price of non-toxic polymers : can that be be true, or is that
fake excuse for selling their product at as high a price as possible (a
pity, since it could be a solution for erosion and drought problems in arid
regions - which, as we know, are most often poor).

Don't know if I came to the right person with this question, but would be
most thankful if there would be a reply or piece of advice....

F (brussels, Belgium)