Wednesday, September 12, 2012

Trees and Lawns–Water Both Deeply


Watering Is Essential

Ansel Ash – from Nebraska submitted these pictures recently on Facebook.  I really think they are shocking. The trees and lawns need to live and thrive.  I am amazed at the underground ecosystem that is being sabotaged by a well meaning homeowner.
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Ansel wrote “And if you wonder if lawn irrigation systems are doing a service for tree roots - this photo says it all. Frequent high intensity watering is great for turf grasses, but infrequent deep watering is necessary for tree roots to develop deeper, healthier root systems. We will see more of this in the future I am afraid throughout many of our landscapes.”

“Ever wonder what a healthy root system for a tree looks like? Well here ya go - in comparison to my last photo. Roots do not grown down like a carrot but spread out far beyond the canopy with deep anchoring roots which stabilize the tree and provide access to subsoil moisture. A vast majority of the roots (75% in most species) are located within the top 12" of the soil profile allowing the tree to  quickly capture and utilize available water and nutrients for health and vigor. This works great for trees in forested environments....but not so well for trees in our community landscapes. Turf grasses will out compete tree roots every time. So mulch and mulch and mulch and recreate that forested floor....but NOT TOO DEEP. Do not need any more of that volcano mulching!”
 
The volcano mulching looks like this. volcano mulch  The crown of the tree where the trunk meets the soil is suffocating.  Air cannot penetrate this heavy layer.  The moisture wrapped around the trunk is an invitation for fungal growth. It also weakens the bark which will promote a safe haven for insects.
mulch trees
These trees have mulch to cover the surface of the root, but allow air and water to find the root zone with a few inches of mulch. Mulch with a degradable material like wood chips or compost. Mulch and adding compost to the base of trees will add nutrients to the soil and will mimic the forest environment.
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Since landscape trees are not able to rely on the natural nutrition that the forest offers, it may be necessary to offer fertilizer to them.  Some symptoms that a tree is stressed include smaller than normal leaves, tip die back, dead branches, and leaf color that is not typical.  Frequently our trees are surrounded by concrete, sidewalks, drives, or streets.  These conditions limit the nutrients available to the tree.
There are professional tree services that can fertilize trees, or lawn and garden centers have products specifically for trees and shrubs for the homeowners to do themselves. 
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fertilizing-tree-roots  fertilizer stakes
 If the trees in the landscape are indicating a problem, don’t assume that fertilizer is the answer.  A soil test will tell the tale.  Send to a lab, and indicate what type of tree is growing in the area.  Different trees have unique nutritional needs, so by telling the lab what tree is being tested will allow the lab to name amendments to supplement the nutrient deficiencies. Soil pH may also be addressed.
Sometimes the tree health is threatened by improper planting.  The root ball was not unwrapped from cables or plastic.  This can cause the roots to grow in circles at the base and never stretch out into the soil. 
roots circleing base of tree
Construction on the site can also affect a tree’s health, if not it’s very life.  Since roots are not buried too deeply, as we can see in the above photo,  they can be damaged by heavy equipment by pushing out water from the soil and compacting the soil.
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A friend of mine recently built a new home with a woods coming up to the lawn at the rear of the lot.  In each of the next three years a tree on the lawn perimeter died - three trees in three years.  The arborist consulted blames the heavy equipment of the construction and grading of the lot as the cause of  unseen damage to the roots. 

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Thanks to Ansel Ash for bringing the picture of the lawn and downed tree.  With more drought conditions, and more irrigation in the home landscape, we may not have seen the end of this destructionWatering lawns more deeply and less frequently is the formula for not only a healthy lawn, but also, healthy trees.

Good gardening practices are going to pay great dividend in protecting our landscapes, trees and lawns.


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