Mature trees are an asset to your landscape and vital to the value and beauty of your property. Deep root fertilization is a professional technique that is performed to improve the health of mature trees. This technique is particularly useful when treating stressed trees. Mature trees located in urban or high traffic locations can suffer because the necessary oxygen, water, and nutrients do not reach the roots. Roots can only grow where oxygen, nutrients, and moisture can be found. Deep root fertilization improves the oxygen content, microbial activity, and nutrient levels around the roots. The proper treatment will increase antioxidant production, photosynthetic capacity and respiration in the tree, and rejuvenate and strengthen the root base.
Deep root fertilization is a process where a high quality nutrient solution is injected into the root zone of trees. Done properly, this technique can improve the quality and increase the lifespan of a tree. If applied inappropriately, this technique may not benefit the tree at all and may even damage it and other surrounding plants. Research in this field is ongoing, and state-of-the-art techniques, as well as knowledge in the field combine to provide the best results. The art behind deep root fertilization is to apply the proper nutrient balance with the correct method for the appropriate duration. The wrong nutrient balance, incorrect depth, or incorrect administration, can end up causing harm to the tree, the surrounding plants, and other ecological activity.
There also are times that such treatment is unnecessary. Mature trees do not always require fertilization. By hiring an ISA Board Certified Master Arborist, you can be assured that he or she will take into account the specific requirements of your tree and its surroundings, and avoid costly mistakes.
Usually, the improvement solution includes both fertilizer and concentrated composted materials. The mixture is a combination of nutrients that is uniquely blended and can be amended as necessary. There are several factors that determine which fertilizer to use and how and when to properly administer.Your soil conditions, especially the pH and organic matter content, are considerations. Additionally, since tree roots coexist with turf roots, the right balance of fertilizer needs to be addressed. An experienced arborist can determine the actual size and extent of a tree’s root system and determine how much, what type, and where to best apply the fertilizer.
There are several ways to treat a tree's root base. The materials can be injected into the root zone either by air (pneumatic) or by water (hydro). A professional can decide which method is most appropriate based on the nature of the root growth and the severity of the soil compaction. The soil injection begins just below the surface and can be as shallow as four inches or as deep as twelve to fourteen inches. Soil injection sites are usually placed two to three feet apart in a grid pattern under the canopy area and beyond the drip line.
Normally, fertilization programs should be repeated once or twice a year. There will be instances where severe root damage has occurred, soil compaction is severe, or other problems are present. In some cases, it may be recommended to increase the frequency of the treatments in order to improve the overall health and vigor of the tree. In other situations, surface treatments may augment a treatment plan.
Sterling Churgin is an ISA Board certified Master Arborist. The ISA Board Certified Master Arborist designation is the highest level of certification that is offered by the International Society of Arborists, a world-wide association of arborists. It is intended to recognize certified arborists who have reached the pinnacle of their profession. In addition to passing an extensive computer-based exam, applicants need to abide by a Standard of Practice which is intended to insure work quality. Less than 2% of Certified Arborists currently hold this certification. ISA certifications are obtained by successfully passing the exam and can be maintained with continued education.
