The Value of Deep Root Fertilization

A fertilization technician applying deep root fertilization.

Published January 1, 2015 By RUSSELL PETERS

We thought it would be helpful to discuss the value of some of the components in our formulated custom organic mixture which are the foundation of our deep root fertilizer programs.

Arborilogical Services injects our custom-formulated, organic mixture as a liquid suspension into the top eight to twelve inches of soil where the majority of a tree’s fine feeder root system develops.

The material is injected into the root zone at approximately 250 psi, or pounds of pressure per square inch. The fertilizer injection process also aerates, or adds oxygen, to the critical soil area around your tree where it is most beneficial. The high pressure also acts to open the pore spaces in the soil, allowing additional air to more easily enter the soil profile, especially in the top eight to twelve inches of soil. The oxygen begins its journey into the tree’s vascular system as if the root system was the tree’s lungs. This oxygen is extremely beneficial in a multitude of chemical reactions and processes your tree carries out every second of every day.

Our fertilizer mixture is not a complex mystery of magical goodies of which we hold the secret formula. It is a fertilizer consisting of tried and true organic properties proven to be effective by top arborists around the world, as being the most important organic materials for healthy root growth for all plants and trees.

One of the most prevalent components of our fertilizer mix is humates. Humates provide a multitude of benefits to both the soil and the tree. Think of them as high-quality compost or organic matter. Humates, in a native forest, are the materials supplied by the decomposing leaves in a nutrient-rich forest floor. A few of the many benefits of humates are as follows:

• Humates increase the absorption efficiency of plant nutrients which reduces the need to continuously add synthetic nitrogen and phosphorous to your soil for root growth.
• Humates increase soil aeration; i.e., increases the oxygen content of your soil.
• Humates promote a greener leaf color and increase the density of foliage.
• Humates promote root respiration and absorption of oxygen.
• Humates promote better drainage in heavy clay soils.
• Humates have additional growth-promoting compounds.
• Humates help make nutrients normally unavailable, in high pH soils such as ours in North Texas, available to your trees.

These are just the highlights of what humates offer to your plants and trees. They are not a quick-fix for soil and tree problems, but over time, offer the most benefit when they are used consistently. Humates become more and more beneficial the longer they are used.

Since 1999, when we began using this formula, our staff has monitored the health of all trees with consistent fertilization and recorded incredible improvements in all trees studied.  We found improved health in those trees we commonly address that are damaged from construction or some other negative impact on the root systems or the environments in which trees are growing.

Another component, making up about a fifth of the material, is soluble potash. Potash is responsible for the following:

• Improving the disease resistance of a tree
• Promoting winter hardiness
• Increasing root growth
• Improving your tree’s drought resistance
• Helping to retard soil-borne plants diseases
• Aiding in photosynthesis
• Building cellulose
• Activating over 60 other plant enzymes

The humates and potash make up nearly 50% of our custom organic mixture. Our fertilization blend also contains a yucca extract to promote a more even soil distribution of all of the materials in your soil. We also add Seaweed extract to supply a myriad of minor nutrients. A small percentage of sugars and other materials that promote microbiological activity are also included. We also add a small portion of growth-promoting bacteria. This component is difficult to quantify or measure; however, we do know that all of these bacteria help plant and tree roots to adhere to and to absorb certain plant nutrients. Growth-promoting bacteria cause no harm, as all of them are found to be is associated with healthy plant roots in the wild.

Two other important components of our mixture are sulfur and iron. Sulfur is a material that aids in moving salts that accumulate in our soils further down in the soil and out of reach of plant roots. These sodium salts have the potential to burn roots, or at the very least, discourage development and survival of the vital fine feeder roots.  The sulfur is added as a liquid component that brings the total amount of sulfur to between 5-10% of our total mixture. Sulfur also has properties that help to reduce our high soil pH levels, making it slightly more acidic. Plants require about as much sulfur as they do phosphorous; and, phosphorous is considered a major nutrient for plants. Our soils contain adequate amounts of phosphorous without needing to add any with our mixture.

In addition, we add iron to our formula. This helps trees produce energy from the process known as photosynthesis. Iron is also partly responsible for the chlorophyll that gives leaves their green color and is a necessary component of photosynthesis. The majority of soil tests performed on North Texas soils will reveal adequate amounts of iron present in the soil. The problem with our soils is that the high pH or alkalinity ties up that iron, so it is no longer available, making it unavailable to plant roots. When we add additional iron along with liquid sulfur, it creates an environment allowing the nutrients to be available to plant roots.

We are very pleased with our custom deep root fertilizer blend and with the positive results our client’s trees experience when they are on any of our custom deep root fertilization programs. We hope that your trees are already on an on-going program. If your trees are not, please contact one of our Certified Arborists to provide a program designed specifically for your trees.

We are often asked, “When is the best time to have the deep root fertilization”? The answer is simple. If you are not on a consistent program, now is the best time to get started. If you are on a regular program, then it is important to consistently have applications made annually, and as often as four times a year depending on the needs of your trees.