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From the Holy Cow Department: Instant Water!

By Christie Nicholson - August 7, 2013

in Materials

The most talented creative minds can draw connections between seemingly unrelated things—like diapers and a field of crops--in order to produce new solutions. That's how Mexican chemical engineer Sergio Jesus Vaelasco created Solid Rain, a highly absorbent polymer scientifically known as potassium polyacrylate. Originally intended to make diapers more absorbent, Vaelasco's blend can soak up water to about 500 times its size, and it looks like large salt crystals:

For landscape architects and environments designers it could mean more creative options for plants in drought-heavy areas. Solid Rain could ensure that green landscapes exist and thrive even in water-scarce urban areas, and other places where greenery has a tougher time surviving and so is conspicuously missing.

And the stuff is fairly inexpensive: For $25 you can buy a pound of it, which can go a long way—10 grams of the crystals can absorb up to a liter of water.

When full of water the crystals form a translucent gel blob that can then provide moisture to plants for up to one year, depending on the size and amount of Solid Rain used. The water never evaporates or runs off—it is only absorbed by the roots of plants. And the plants don't absorb the polymer because it is, oddly enough, insoluble in water.

On Mexican farms, Solid Rain has showed a proven increase in crop yields by up to 300 percent. Because the product is highly efficient, doses are quite low, making them profitable for farmers. You can use 25kg per acre for a surprisingly-long stretch of up to 10 years.

Homeowners or anyone in landscape design will also find the product easy to use: For a lawn, you just mow it, make holes, place either hydrated Solid Rain or have it mixed with soil—and then bury it in the holes, cover and water. The benefits are shown here with a side-by-side comparison of two lawns. The very green one, treated with Solid Rain, is watered only 35 times per year, while the untreated, dry one, sucks up 300 waterings annually.

While the greener grass or more abundant crops is something you can see in the photos, there is an additional benefit that you can't see:

A great benefit beyond the added moisture is the preservation of nitrogen in the soil. Because little watering is needed, the nitrogen is not as likely to be washed away. It's been nominated for a Global Water Award by the Stockholm International Water Institute. And it's been used in Mexico for more than a decade. It only arrived in the U.S. less than a year ago.

Since climate change is creating an increasing and troubling uncertainty in global weather patterns, Vaelasco's invention may continue to be a critical solution for areas hit by unexpected droughts. Of course, any water conservation project is a good thing, so Solid Rain may inspire new designs for distributing the crystals in ways that could help us all—regardless of climate.

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Rebekah

11 years ago

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As much as I can get behind the idea of steadier supplies of water to crops, I worry about the product itself and the long-term effects of something like this being put in the soil. What happens to the product after a year, or five, or ten, in terms of chemical breakdown? Does it absorb only water, or will pesticides and other chemicals (spills from floods, urine, etc) be absorbed and the feed the plants as well?

Obviously this will provide water for plants, but not enrich the soil with nutrients, so once crops are rotated or the land is repurposed, perhaps for housing or commercial real estate, how will it change the architectural needs (possibilities for sinkholes, quicksand, foundation problems, etc)?

Hopefully there are people more knowledgeable than I who are already thinking about these aspects of the product and its usefulness. This would be a great boon to farmers, especially in drought-prone areas.
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Evan Jones

11 years ago

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Wow, that's exciting! BUT I went and dug some more and... check out this response from a PhD horticulturist. Basically, within 5 years, the gel breaks down into carcinogenic and neurotoxic acrylamide and the soil stops absorbing water.

http://puyallup.wsu.edu/~linda%20chalker-scott/horticultural%20myths_files/myths/hydrogels.pdf
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Tal

11 years ago

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Possibly not so straight forward: http://puyallup.wsu.edu/~linda%20chalker-scott/horticultural%20myths_files/myths/hydrogels.pdf (as linked to by Grist http://grist.org/list/solid-rain-keeps-plant-hydrated-even-in-droughts/)
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Luke

11 years ago

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That's weird. Moss gardeners have been using sodium polyacrylate for decades (just do a Google search for "moss milkshake"). I've personally been using it for grass on my desk for years now, and I've heard of people using it in their vegetable gardens too.

I find it a little hard to believe that it's only now being applied to large-scale agriculture, even after being used in fighting wildfires. If true, though, props to Vaelasco for finally commercializing this. It's so obvious that I just took for granted its agricultural uses.

Keep in mind, though, that this isn't a magic bullet that'll solve all the world's agricultural woes. As useful as it is, I'm skeptical about its ability to keep plants quite so green and healthy; I don't personally see results like that with my grass planters. Also note that plants which require well-drained soil could well be harmed by this substance.
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