More than you ever wanted to know about water movemnet in soil

I want to apologize about the recent "update" on this blog posting that seemed to be incomplete.  It was!  What happened was I was working on this posting behind the scenes, but didn't publish it.  Then one of my friends told me about a new Ipad app that would allow me to work on the blog via my Ipad "on the fly" so to speak.  So I downloaded it and tried it last night...it didn't turn out so well.  I hit the wrong button, what I was working on got posted, and when I tried to fix it the app froze up.  Below is the finalized version of what I was working on.  Sorry for the confusion, but here we go....Soil Hydraulics, fasten your seat belt!

It has been often said amongst turf professionals that if you want a good golf course it takes three things...drainage, drainage, drainage.  If you think about the game of golf the concept is very true.  Good drainage promotes a firmer surface, better growing media for the grass and all of that translates into a happier golfer.  Nobody has ever been turned away from a tee time because the Superintendent has said "Sorry, the course is closed because we just drain too fast and the playing conditions are too firm."

We have all seen drains and we all know their purpose, water goes in the drain and is piped to the lakes.  What is usually unknown is what happens to water in the soil and why do wet spots occur.  In my last posting I explained what we were doing about wet spots and showed you how I was fixing the problem by installing some physical improvements.  This time I want to try and explain why we needed to do what was done.

The most important concept to remember in dealing with water movement through soil is that water does not like layers.  When water being pulled downward by gravity hits a layer, it stops!   Look at the picture to the left and you can see an illustration of what I am talking about.  In the top picture you can see an inverted bottle of water resting on the top of the soil.  If you look at the curved lines and follow them to the left you will see numbers representing time in minutes.  Now notice after 50 minutes the water is not moving any farther down.  The reason is that the water in the soil has hit a horizontal layer.  Notice in the top picture that the water seems to be "boxed in" on the sides.  This is due to vertical layers on each side. Another important rule in soil hydraulics is that water will not move through a layer until the entire uniform soil profile is filled up.  This is why the water filled the entire soil profile within the "box" surrounded by the layers before it moved laterally again.

In the bottom picture, if you  look at the numbers on the left (sorry for such a small picture, it was the only one I could find) and correlate them to the top you can conclude that it took 50 minutes for the water to move straight down from the initial infiltration point, but due to the different layers in the soil it took almost 200 minutes for the water to fill the "box" and move through the vertical layers and begin moving downward again. 

Now that you have the basic concepts of how water is going to move through the soil, imagine the tortured path water has to traverse in the soil on the golf course where the soil profile looks like a bucket of vanilla / chocolate swirled ice cream.  This layer issue is one reason why wet spots form and why after a rain I restrict golf carts for a while.  Even though the surface water has made it's way into the drain basins, the soil water needs time to drain before carts drive over the soggy soil.

A natural question would be "Why is it an issue now when it wasn't right after the course opened?"  Initially when the golf course was built the soil was loose and soil water moved much quicker.  In construction terms, it had fluff in it.  Now that the golf course is a couple years old the soils are tightening up and soil structure is changing a little bit.  Don't worry, adding spot drainage is something that is very normal and needs to be addressed annually as the course matures.  Next year we will do more drainage, the year after that too, and so on.  Remember, to have a great golf course your have to have three very important things...