Tree Health Management

In urban and suburban settings, there are fewer nutrients in the soil, thanks to prior construction and a lack of decaying organic matter. Unlike in forested settings, where plants, trees, leaves, sticks, moss, fungi, and other forms of life are constantly adding new nutrients into the soil, residential and commercial settings need some assistance.

That’s where fertilization comes in. Fertilizers add needed nutrients to the soil, helping trees, plants, and lawns stay healthy. In some cases, fertilization can help a struggling tree. In others, it might prevent some tree health issues.

Applying fertilizer at the correct time can be the difference between success and failure. Fertilizing at the wrong time can lead to runoff, unhealthy trees, and plants forced to grow when they should be focused on other functions.

There are exceptions, but in general, the best time to fertilize is during the spring and fall. Of course, first knowing the composition of the soil and what nutrients are lacking can make fertilization more effective, which is why we suggest a soil test.

Synthetic fertilizers contain nutrients that are created in a lab, whereas organic fertilizers are derived from minerals and animal or plant waste products.

Since the nutrients in synthetic fertilizers are from a lab and organic fertilizers are made with things found in nature, organic fertilizers tend to have more micro-nutrients than synthetic. They also tend to be more environmentally friendly and cause less harm to wildlife, water sources, and pets.

Organic fertilizers are usually slow-release and provide a steady amount of nutrients to your soil. Synthetic fertilizers tend to be quick-release, and often need to be applied more frequently. Because of their lower rate of decomposition, organic fertilizers can be gentler on trees and more consistent in releasing nutrients but are also less concentrated.

Organic fertilizers tend to cost more than synthetic and often rely on moisture and/or heat for the materials to properly break down.

The type of fertilizer used depends on your property goals, what your trees, lawn, or landscape plants need, and what the soil test reveals about the nutrients in your soil.

Based on that information, the best fertilizer is the one that matches your needs, budget, and soil health. Occasionally, more than one type of fertilizer may be used.

We recommend a soil test to determine what nutrients your soil has and which it lacks. Knowing the makeup of your property’s soil will help us determine which fertilizer (or fertilizers) would work best for your plants.

Granular fertilizer is often in the form of small pellets and is sometimes multi-colored. It’s commonly used in lawn fertilization and is generally less expensive than liquid fertilizer. The different colors of granules may represent different nutrients, depending on the type used. Granular fertilizer is applied to the soil surface and is slowly absorbed into the ground. It usually has more salt content than liquid fertilizer.

Liquid fertilizer can be applied by spraying or by injection into the soil, depending on the type and purpose of the fertilizer. The nutrients, which are mixed together, are much more quickly absorbed by plant roots, which means that plants receive the benefits of the liquid fertilizer soon after it is applied. Liquid fertilizer tends to contain less salt than granular fertilizer.

Deep root fertilization injects fertilizer directly into the soil around the roots, called the root zone. This reduces the chances of the fertilizer going anywhere other than where it needs to be and makes it easier for plant roots to quickly absorb the nutrients.

This method of application also often aerates the soil, providing needed oxygen to roots. This is especially helpful if the ground is compacted.

Nitrogen, phosphorus, and potassium (often referred to as NPK) are three macronutrients that are needed for plant life. So-called “complete” or “balanced” fertilizers will contain a mix all of three. However, if there is too much or too little of any of those nutrients, it can cause issues.

Unlike other nutrients, phosphorus does not naturally leach out of soils, so it can build up over time. This is often the result when manures or non-organic fertilizers are used multiple times in the same area.

If a soil test shows a build-up of phosphorus in your soil, your plants may have already shown signs of yellowing and withering. Phosphorus blocks a plant’s ability to take up other nutrients, such as iron and zinc.

When applied to the soil surface, such as with a granular lawn fertilizer, phosphorus can be spread to nearby streams, lakes, and other water bodies in runoff from irrigation or rain. Excess phosphorus stimulates the growth of weeds and algae ponds and waterways, resulting in green scum-covered waters and negatively affecting the entire ecosystem. Too much of this macronutrient also reduces the amount of dissolved oxygen in the water, with deadly outcomes for fish and other aquatic life.

It’s not possible to reduce the amount of phosphorus that is already in your soil, but you can restrict the use of fertilizers that contain phosphorus in the future.

We also recommend re-testing your soil once a year to check how the nutrient levels have changed.

Yes, it is possible for a tree to get too much nitrogen. When it does, some signs and symptoms seen in the tree and the surrounding area may include:

• an excess amount of leaves (or larger leaves)
• dehydrated leaves that look burnt (yellow or brown leaf edges that wilt)
• slowed root growth, which can lead to an unstable tree
• increased pest infestation
• root issues or disease
• groundwater pollution as nitrogen leaches out through water runoff

Again, a soil test can inform you if there is too much nitrogen in your soil. A professional from Riverbend Landscapes and Tree Service can help you with a fertilization plan to fix any nutrient issues.