December 21, 2015

avalanche column

December 3, 2015

One of the ways to protect crops from freezing is the use of water.

For freeze protection to work, the water needs to sprinkle on the plants for the whole event. This must start before the freezing begins and continue until the temperatures rise above freezing.

This is chemistry and a wonderful property of water. When water freezes it expands. Put a jar of water in the freezer and neglect to leave enough head space for the water to expand. When the jar is removed (if you are lucky) just the lid has been forced off. A glass jar with a screw on lid will be shattered. Luckily until the jar thaws it will stay in tack.

It is this expansion that traps air in the ice and thus insolates whatever is underneath.

A very interesting thing happened when MOUNT St. Helens erupted in Washington State in 1980. It was in the spring before any of the spring thaw started. All of the lakes and ponds were frozen solid. I recall a very small pond where the landscape was reduced to bare dirt but because the small pond was frozen all of the fury of the explosion just passed over this pond leaving all of the aquatic life under the ice in tack. In the spring when all the rest of the landscape was destroyed there was this little jewel in the middle of all this destruction. This is a wonderful example of the amazing properties of ice.

Back to crop protection, how does it protect the crops and why must the water remain on for the duration of the event. Time for very basic chemistry, when water begins to freeze there is a very little amount of heat that is generated just as the water converts to ice. In order for this to protect the plants and to continue “generating” this heat of cooling, the water must remain on.

This is why if you see fields of strawberries that this method of freeze protection has been used, the field looks like a very bumpy ice skating rink.

Recently we had a couple of very interesting weather events collide over the top of West Texas. There were the remnants of a hurricane from the west coast of Mexico and a strong Artic cold front. Luckily the hurricane arrived before the Arctic cold front.  The rain started before it became freezing and continued until the freezing ended. Sound familiar from above. And so the ice built throughout the night.

 I recently decided to finish harvesting the rest of my tomatoes. I did not have a chance to pull the plants. In regards to freezes, this event never got too cold, 31 degrees. Maybe the hurricane scoured out some of the cold with the excess rain. But how surprising to come home from market to see live tomato plants that were all uncovered and very healthy looking.

Questions? I can be contacted at markdirtfarmer@gmail.com. Or more garden notes at redwagonfarm.blogsot.com