Sunday, May 25, 2014

Capillary Water

Capillary Water

Water is a fascinating substance, renowned for its chemical properties.  This is the reason scientists believe it is essential for life, and so much of our search for life elsewhere is based on finding water first.  Detailed here is one of the less understood but utterly essential properties of water - capillary action.

Capillary action is the ability of water to lift itself up the sides of narrow tubes.  Water does this by forming bonds (called hydrogen bonds) with the sides of the tube it resides in.  This property of water - binding to another substance - is called adhesion, while water's bonding to itself is called cohesion.  This is very evident in a glass rain gauge, where the water on the sides of the glass curves upward (making the water form a concave meniscus).  This effect is more pronounced the thinner the tube, lessening the depressing effects of gravity in the center of the meniscus.  A somewhat opposite effect is seen with the element mercury, which is more attracted to itself than to the glass walls of a tube.  

File:Capillarity.svg
From Messer Woland via Wikipedia
Without water's capillary action, life would not be possible.  Trees and other plants rely on capillary action to "wick" up water from the soil in narrow tubes called xylem.  The water is released from the leaves in a process called transpiration.  Water, which is itself necessary to the plant, is also an excellent solvent and carries nutrients to where the plant needs without a pump.  

The soil is also dependent on capillary action, as it has many small pathways formed by microorganisms.  This is the way in water is able to spread both laterally throughout the soil, as well as from deeper (where aquifers are present) to higher up.  This water then evaporates from the top layer of the soil unless something blocks the sun.  This is clearly evident by lifting up a stepping stone on a hot sunny day, and feeling the soil beneath it versus the soil around it.  The ground underneath the stepping stone is moist, while the ground around it is dry.  

 Nature doesn't need to dig a well and insert an electric pump to move water; it uses this capillary action.  We ignore Nature's wisdom when we ignore this phenomenon.  Nature does rain, but this can be infrequent, and it doesn't need daily or even weekly watering of seeds to keep them alive because seedlings can get water from the ground via capillary action.

 Capillary action can be easily demonstrated by placing colored water in a bowl, and then inserting a strip of paper towel as below:


You can see water working against gravity climbing up the paper towel.  The same process happens in the soil through the capillary channels already established there.  Feel free to try this simple experiment at home to help children (or yourself) understand capillary action.

It is important to note that capillary water is not ground water in the traditional sense.  Capillary water is water held by physical forces only a few (<10) feet from the surface, while ground water is much deeper where there is enough water to saturate the soil.  Plant roots rarely reach ground water (except in places with a high water table) but still do very well by accessing capillary water.  In deserts where the water table (ground water level) is extremely deep (if present at all), trees survive by roots accessing capillary water.

So consider the traditional tree planting method in light of what you learned above.  You buy a tree from a nursery in a pot.  You dig a large hole for that pot (with current recommendations being as deep and twice as wide as the root ball) - disturbing both the bottom and side capillary channels in the soil - essentially guaranteeing that the tree will quickly dry out without watering from above (namely, you or an irrigation system).  You then have two choices for preventing evaporation of the water from the soil around the tree.  Choice one is wood mulch, which works fair but allows weeds and grass to grow through, robbing the tree of water and space.  Also, mulch is made of wood, and wood is porous to water, so you still get considerable evaporation.  Your second choice is the rather expensive rubber tree mats made from old tires.  The good news is that these vulcanized rubber mats are almost completely impermeable to water, preventing evaporation of water from the soil.  The bad news is that the vulcanized rubber mats are almost completely impermeable to water, preventing almost all rainwater from reaching the roots beneath them.  All of this means that the tree will need to be watered by human intervention until the roots grow down to capillary water and the tree canopy becomes large enough to cast a shadow on the soil beneath it, preventing evaporation from the soil.  We will call the method just described the electric water pump method of tree planting because it uses a great deal of unnecessary energy and materials to replicate a system Nature has already perfected.

From Groasis.com, explaining the benefits of capillary water and the problem with traditional planting of trees

Compare this to planting a seed or small bare root tree with the Groasis Waterboxx.  The Groasis Waterboxx is a brilliantly conceived water battery for trees, which uses the principle of capillary water to plant trees in dry climates. If planting a seed with the Waterboxx, the seed is placed directly on the existing soil and in contact with the capillary channels of the soil.  The primary root sprouts, and is sustained both by water coming up from the soil as well as water dripping down to it from the reservoir of the Waterboxx (the Waterboxx is refilled with dew and rain water, without human intervention).  The specialized UV resistant plastic of the Waterboxx prevents evaporation and drying out of the soil beneath it (like the rubber mat).  However, unlike the mat, it channels rainwater directly to the roots (like the wood mulch) with its lotus leaf inspired lid.  Unlike the wood mulch, the Waterboxx prevents grass and weed growth around the tree, will last for many years, and can be reused.  The Waterboxx combines the best features of both the synthetic and the natural.

If planting a small bare root tree, the principles are the same as planting a seed, but the primary root is inserted directly into a small hole in the soil beneath the Waterboxx.  The primary root (taproot) receives enough water from the Waterboxx to grow, and roots grow only where there is water, so its primary root pushes deeper until it reaches deeper underground capillary water. The Waterboxx is removed at this time (which is usually evidenced by a growth spurt). We will call this method the Natural Method, or perhaps the Efficient Method.

It is small wonder that the Waterboxx both increases tree survival rate and increases the rate of tree growth.  The Groasis Waterboxx took seven years and 7.1 million dollars to develop, with every possible consideration given.  It has successfully been used to grow trees in the Sahara desert with 88% success rate.  The Waterboxx can be purchased here.

In addition to increasing the survival rate of trees, the Groasis Waterboxx also helps landowners conserve water.  If you do decide to try out the Waterboxx, check the cost of your water bill for a given month before the Waterboxx and after.  The Waterboxx can have a significant positive effect, rainfall and other variables being kept equal.  You can use our Waterboxx cost calculator here.

We document the success of the Waterboxx growing many things elsewhere on this site, from Giant Sequoia and red oak, to pear trees and pumpkins.   We have more information on the Waterboxx at hour main Dew Harvest site here.   You can also buy the Waterboxx at our website.  Be the first in your area to start growing plants with the Groasis Waterboxx today.

For more information about capillary action, please see our sources: 

http://science.jrank.org/pages/1182/Capillary-Action.html
http://www.ec.gc.ca/eau-water/default.asp?lang=En&n=BCCCF74B-1#tension
http://en.wikipedia.org/wiki/Capillary_action
http://www.madsci.org/posts/archives/1998-02/887637827.Ch.r.html
http://www.biologylessons.sdsu.edu/classes/lab1/semnet/hydrogen_bonding.htm

http://ga.water.usgs.gov/edu/capillaryaction.html

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