#cépages

#cépages #hybrides

une chercheuse américaine a quelques doutes sur l’innocuité du produit :
►http://www.puyallup.wsu.edu/~linda%20chalker-scott/horticultural%20myths_files/myths/hydrogels.pdf

My initial concern with hydrogel usage is the public perception that it is a permanent fix. Hydrogels are routinely touted as pH-neutral, non-toxic, environmentally friendly compounds, which they are in their polymerized form. The fact remains that after five years virtually all hydrogel will be depolymerized
through natural decomposition processes. The rate of degradation is increased especially in the presence
of fertilizer salts (and no, it doesn’t make any difference if these are synthetic or organic fertilizers).
One is then left with the original soil conditions; in a permanent landscape, this can be problematic unless
other water-conserving steps are then implemented.
My second, and probably greatest, concern occurred when I discovered that hydrogels are constructed of
acrylamide units. When hydrogels break down, they release potassium acrylate and acrylamide.
Acrylamide is a lethal neurotoxin and has been found to cause cancer in laboratory animals. It readily
passes through the skin and can be inhaled as dust. Unfortunately, the chemical data sheets on hydrogels
do not mention the fact that within a few years they will be composed entirely of these acrylamide units.
Since polyacrylamide is defined as “not readily biodegradable” (less than 10% is degraded after 28 days),
some sellers of hydrogels actually promote their products as “nonbiodegradable!”

▻http://modernfarmer.com/2013/07/powdered-water-just-add-water

Solid Rain has been nominated twice for a Global Water Award by the Stockholm International Water Institute, it received the Ecology and Environment award from the Fundacion Miguel Aleman, and it’s been used in Mexico for a decade.

et une réponse (dans le forum) aux craintes exprimées sur l’acrylamide :

Potassium polyacrylate is a polymer (meaning, it has repeating units of) acrylic acid. Polyacrylamides are polymers of acrylamide. The basic units, acrylic acid and acrylamide, are similar - the former has a carboxylic acid functional group (carbonyl attached to an OH) and the latter has an amide (same thing but with a nitrogen-based group at the end instead of OH). That difference may seem small, but in organic chemistry terms, it is a very big difference. One that means one compound is toxic while the other is not. So, even though they sound the same (they both have acryl- prefixes), they really are quite different.

Donc, c’est plutôt une bonne idée, à l’arrivée.

Sinon, je regrette encore de n’avoir pas référencé correctement une autre news sur deux étudiants qui avaient trouvé le moyen génial de fabriquer des plaques photovoltaïques sur n’importe quel type de verre, des plaques grossières, de manière donc très économique et nettement plus écolo que ce qui se fait maintenant, le genre de truc qui permettrait à chacun de se faire son #photovoltaïque à la maison.
Je me disais que c’était l’idée du siècle, mais que, comme pour les #cépages_hybrides qui permettaient à tout le monde de faire son petit picrate à la maison sans un grand niveau d’expertise, il devait y avoir des entreprises qui n’avaient absolument pas envie que ça devienne trop facile de produire soi-même son énergie et qui ont dû tout faire pour que l’idée n’aboutisse pas.