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Fertilizing Your Landscape Plants Properly
Marie Wakefield
Maintenance programs should be developed for trees and shrubs for your landscape. A good maintenance program includes monitoring and controlling insect and disease problems, suppressing weed competition, and making timely applications of water, mulch, and fertilizer.
Tree and bush fertilization is particularly crucial in urban and suburban areas of the country where soils have been changed due to building. These urban lands incline to be heavily compressed, poorly oxygenated, poorly drained, and short of organic matter. Even where soils haven't been stricken, fertilization is possibly needed as part of a sustainment program to step-up plant vigor or to improve root or crest growth.
Trees and bushes in residential and commercial landscape plantings are frequently fertilized to keep them flourishing and attractive. Over-fertilization is frequent, inducing excessive growtht, particularly in immature nursery stock. Trees growing in lawn expanses usually get some nutrients when the grass is fertilized. This is normally adequate to maintain most trees in prolific soil. However, fertilization could be required on altered soils wherever unconsolidated fill material has been superimposed or the topsoil has been removed. Managed urban areas where fallen leaves are dispatched may also call for a fertilization program to enrich soil and replenish nutrients.
Fertilizer is no stand-in for environmental factors, such as sunlight and water, which must be in balance if a tree or shrub is to grow into its full potential. Trees and shrubs that are healthy and growing robustly are less susceptible to attack by insects and diseases. An application of fertilizer may, in some instances, improve the plant's resistance to further infestations of certain pests. For example, maple trees will recover from mild cases of Verticillium wilt following applications of nitrogen fertilizer.
Fertilizer Objectives
How and when to fertilize landscape trees and shrubs depends on:
Maintenance objectives (stimulate new vs. maintain existing growth)
Tree and shrub ages (generally more for younger and less for older plants)
Plant stress levels
Time to Fertilize
The top time to fertilize trees extends from late fall, after the leaves have fallen, through the winter and into early spring before vigorous new growth occurs. Fertilizer applied in the fall has a longer time period to penetrate the soil enabling the roots to more efficiently absorb it. The fertilizer is taken up by the roots during the winter and is available to the plant for growth in the spring.
Trees that are fast growing should be fertilized yearly. Well-established, mature trees usually require fertilizer once every three to four years.
Fertilizing Newly Planted Trees
Freshly planted trees typically do not need fertilizer during the 1st growing season. Almost all transplanted trees produced in the nursery have elevated levels of nutrients that last through the 1st growing season. Exuberant fertilization during the first year could harm the tree and cut back its rate of development. After the 1st year, nitrogen can be utilized in a roughly 3ft area around each tree. This will assure a satisfactory supply for continued development. Don't apply fertilizer within 12 inches of the stem of the tree since fertilizer can burn and injure young stem tissue.
How to Determine Whether to Fertilize
Visual inspection of trees and shrubs is often the best overall factor to use in making fertilization decisions.
Look for:
Poor leaf color (pale green to yellow)
Reduced leaf size and retention
Premature fall coloration and leaf drop
Soil Test
18 nutrients are required by plants: carbon,oxygen, hydrogen, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur and 9 trace minerals: iron, boron, copper, manganese, molybdenum, zinc, cobalt , nickel and chlorine. Carbon , oxygen and hydrogen operate in the formation of plant cells and food fabrication, the first two furnished from the atmosphere and the latter received from water soaked up by roots.
A soil test furnishes specialised data on the potential for plant reaction to agricultural limestone and to phosphorus and potassium fertilizers. In addition it provides a verifiable basis for ascertaining how much of those elements to add once they are found to be lacking. A representative soil sampling can be a challenge to get, because most nutrient-absorbing roots of trees and bushes are in the upper six inches of the soil and may stretch out two or three times beyond the radius of the crown. Consequently, in determining the nutritional demands of trees and shrubs, it's also essential to look at soil and moisture conditions; the species, age and vigor of the plants; and previous fertilization.
Nitrogen, the most typically depleted soil nutrient, furnishes the greatest growth response. Unfortunately, soil tests or analyses for accessible nitrogen are not very dependable. Nitrogen is present in different forms (e.g. nitrate, ammonium, urea) and these forms can alter rapidly in the soil. All the same, overall tree growth, especially root and shoot elongation, leaf color and leaf size, can be heightened with increases of nitrogen. Be sure not to overfertilize with nitrogen. Don't overcompensate with greater amounts of nitrogen when fertilizing grass, bushes and trees. Nitrate leaches readily from numerous soils and can create water pollution problems.
Selecting a Fertilizer
A variety of fertilizer types exist:
Complete (N-P-K) vs. incomplete (one or more select nutrients)
Organic vs. inorganic
Fast release vs. slow release
Dry (granulated, pelletized, spikes, pulverized encapsulated) vs. liquid
To assist in determining the form of fertilizer to utilize, weigh these factors: type of flora, season, wanted rate of plant reaction, application program and equipment price, proximity to water sources, consequence of soil type and pH, type of deficiency, and outcomes of a soil test or additional sampling methods.
Nearly all landscape plants profit from a slow secreting nitrogen fertilizer that can be organic or inorganic. Remember that nitrogen is easily washed through the soil, but phosphorus and potassium are not, signifying they necessitate less frequent application.
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.
Direct application of fertilizer may involve incorporation into the backfill soil or placement in the planting hole at planting time. However, the most common form of direct fertilizer application, broadcasting, is generally the most effective, especially relative to cost. Simply placing the desired fertilizer over the soil atop the tree and shrub roots and watering it in is usually adequate. Compacted soil should first be aerated or raked.
The most serviceable and expeditious way to fertilize sizeable trees is to disseminate granular fertilizer on the surface of the dirt and permit rain or irrigation water to move the nutrients down to the roots. Uniformly disperse the fertilizer over the area to be fertilized - that expanse covering the outer two-thirds of the distance between the tree 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.
An often utilized commercial process is to inject liquid fertilizers into the soil. A specialised injection probe is utilized and the fertilizer solution is injected under pressure. A corresponding probe device known as a 'root feeder' is sold at nearly all garden centers. The elongated probe attaches to a garden hose and water-soluble plant food cartridges deliver nutrients and water directly into the tree root area. The tip of the injection needle ought to be entered four to twelve inches into the soil at two- to three-foot intervals. Fertilizers appropriate for fluid injection are usually costlier per unit of nutrient and are often harder to apply than granular fertilizers.
Spikes are another alternative for tree or shrub fertilization. These are pounded into the soil with a heavy hammer and can only be used successfully when the soil is moist. The spikes do not evenly distribute fertilizer around the tree's or shrub's major feeder roots. These spikes are an expensive alternative. Their reputation is based on simplicity and ease of application.
Foliar feeding is a quick-fix solution when a nutrient deficiency has been found. The leavesl, buds and green wood are capable of a little nutrient absorption. Foliar nutrient sprays are applied with a pressure sprayer or siphon sprayer attached to a garden hose. The greening from foliar spraying is fairly quick but not long lasting. More often than not deficiencies of micronutrients including ironl, boron or manganese are corrected 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.
Fertilizer Placement
Fertilizer shouldn't be focused around the base or trunk of a tree or bush, but should be put on as much of the plant's root zone as feasible. For trees and bushes, fertilizer ought to be put on an area double the crown spread. Because most landscape plant roots grow in the top foot of soil,shallow, not deep application, is suggested.
Factors Affecting Fertilizer Uptake
Many factors affect how well and well trees and shrubs absorb fertilizers. The most important uptake factors are:
Fertilizer form (inorganic, fast release, or liquid forms are absorbed faster than organic, slow-release,or dry forms)
Soil type (clay particles and organic matter soak up or bind more nutrients than sand, so fertilizer application needs to be more often in sandy soils, but with lower rates each time due to leaching potential)
Soil moisture content and soil warmth (nutrient uptake is faster in moist warm soils)
Plant vitality (plants under stress are less able to take up available nutrients due to damaged or reduced root systems)
Timing of Application
Fertilizer should be utilized when plants require it, when it will be most efficacious, and when plants can readily accept it. Late summertime and early autumn fertilization may hasten new growth that is not winter hardy, and summer drought could interfere with nutritive uptake, but spring, fall, and wintertime applications are satisfactory. A split application might be advantageous, applying half the annual rate in early spring and the balance in the fall as or after plants go dormant.
If water is unavailable, don't fertilize altogether - plants will be unable to assimilate the nutrients. (During a dry time of year, fertigation - application of fertilizer by means of an irrigation system can be beneficial.)
Tree and shrub fertilization is only one ingredient of total plant maintenance. Fertilization may not assist a plant if it is under stress from poor soil aeration or drainage, saturated soil, inadequate light or space, or excessive pest problems. All factors influencing plant growth should be kept at optimal levels to ensure plant vigor.
For healthy landscape and other better landscaping ideas visit http://www.better-landscaping.com/Site_Map.html
Article submitted Sunday, July 13, 2008
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