Fertilizing Landscape Trees and Shrubs Part 3

Methods of Application

Fertilizers can be applied either directly or indirectly to plants. When turf is fertilized, tree and shrub roots that extend into the turf area absorb some of the fertilizer, and are therefore indirectly fertilized. Turf fertilization rates should be supplemented only if trees and shrubs are showing symptoms of nutrient deficiency.

Straight application of fertilizer could call for placement into the backfill soil or positioning in the planting hole at planting time. Nevertheless, the more common variant of direct fertilizer application, broadcasting, is typically the most useful, especially proportional to cost. Just broadcasting the fertilizer over the soil atop the tree and bush roots and watering it in is generally enough. Compressed soil should first be aerated or raked.

The most sensible and efficient way to fertilize large trees is to scatter granular fertilizer on the surface of the soil and allow rain or irrigation water to transport the nutrients  to the roots. Evenly broadcast the fertilizer over the area to be fertilized - that area covering the outer two-thirds of the distance between the trunk and the drip line and extending at least 50 percent of the crown radius beyond the dripline.

An alternative method is to position granular fertilizer into holes in the ground that are four to twelve inches deep. These holes are constructed in a regular pattern at 2- to 3-foot separationsl,  in the same expanse as broadcast fertilizer is applied. Divvy up the fertilizer amongst the holes. This process does not insure homogeneous coverage to all feeder rootsl, particularly in the upper few inches of the soil surface where the bulk of the roots occur. Strong concentrations of fertilizers in these holes can in addition injure roots located next to the hole.

A commonly used commercial method is to inject liquid fertilizers into the soil. A special injection rod is used and the fertilizer solution is injected under pressure. A comparable probe mechanism called a 'root feeder' is sold at most garden centers. The long probe attaches to a garden hose and water-soluble fertilizer cartridges distribute nutrients and water directly into the tree root zone. The tip of the injection needle should be inserted 4 to 12 inches into the soil at 2- to 3-foot intervals. Fertilizers suitable for liquid injection are typically more expensive per unit of nutrient and are frequently more difficult to apply than granular fertilizers.

Spikes are additional choice for tree or bush fertilization. These are rammed into the soil with a heavy hammer and can only be employed effectively when the soil is damp. The spikes don't evenly broadcast fertilizer around the tree's or bush's major feeder roots. Tree spikes are a pricey choice. Their popularity is founded on simplicity and ease of application.

Foliar feeding is a short-run answer when a nutrient inadequacy has been diagnosed. The leavesl, buds and green wood are able to absorb some nutrients.  Foliar nutrient sprays are put on with a pressure sprayer or siphon sprayer attached to a garden hose. The green-up from foliar spraying is fairly speedy but not long enduring.  Generally deficiencies of micronutrients including ironl, boron or manganese are rectified by seasonal foliar applications.

Micro-injection constitutes the direct injection of necessary nutrients into the trunk of the tree or bush. It's an acceptable commercial use for remedying or invigorating trees demonstrating stress or decline symptoms. Nutrients can as well be solidified into gelatin capsules and imbedded in holes in the trunk. Micro-injection research is comparatively limited and outcomes are often conflicting. Boring holes, imbedding or injecting fertilizer and sealing holes could lead to trunk disfigurement and decay. Foliar applications, injections or implants would better be used only when soil application of fertilizer is unrealistic.  These routines are regarded as short-term remedies for nutrient deficiencies and pest infestations. In the final analysis, suitable soil and foliar applications must be applied for a permanent cure.