Chapter 5: Tree Nutrition and Fertilization Flashcards
essential element
17 minerals essential to the growth and development of trees; these minerals are essential because plants cannot complete their life cycle without them; chemical constituent that is involved in the metabolism of the tree or that is necessary for the tree to complete its life cycle
Benefits of fertilizing trees?
increase growth, reduce susceptibility to certain diseases and insect pests, and even help reverse declining health
macronutrient
essential element that is required by plants in relatively large quantities
What is often the most limiting macronutrient and the one required in the largest quantity?
Nitrogen (N); a constituent of proteins and chlorophyll and is critical to photosynthesis and other plant processes
leaching
tendency for elements or compounds to wash down through the soil; tendency for elements or compounds to wash into the soil; volatilization; washing of chemicals down through the soil
chlorosis
whitish or yellowish leaf discoloration caused by lack of chlorophyll; often caused by nutrient deficiency
signs of Nitrogen deficiency
reduced growth, smaller leaves, and yellowing (chlorosis) of the older leaves
Examples of macronutrients
Nitrogen (N), Phosphorus (P), Potassium (K), and Sulfure (S)
secondary nutrients
mineral element required in moderate amounts by plants
Examples of secondary nutrients
Magnesium (Mg) and Calcium (Ca)
micronutrients
essential element that is required by plants in relatively small quantities; may actually be toxic at high levels
iron chlorosis
condition that results when trees are not absorbing sufficient quantities of iron, often because iron in the soil is in a form that roots cannot absorb
Examples of micronutrients
Iron, Manganese (Mn), Zinc (Zn), molybdenum, copper, chlorine, nickel, and boron
complete fertilizer
fertilizer containing the three primary elements: nitrogen (N), phosphorus (P), and potassium (K)
fertilizer analysis
percentage of primary elements [nitrogen (N), phosphorus (P), and potassium (K)] in a fertilizer; expresses the composition of the fertilizer as a percentage by weight of the total nitrogen (N), available phosphoric acid (P2O5), and soluble potash (K2O) always listed in the same order
order of the fertilizer analysis
- ) nitrogen
- ) phosphorus
- ) potassium
organic
in chemistry, a substance containing carbon; in applied arboricultural context, a substance, especially a fertilizer or pesticide, of animal or vegetable origin
inorganic
not containing carbon; not containing organic material
inorganic fertilizer
fertilizer not containing organic material that releases elements relatively quickly when dissolved in water
organic fertilizer
fertilizer of animal or vegetable origin that releases inorganic ions more slowly as materials decompose and molecules are hydrolyzed in the soil; composed of carbon-based molecules and can be either synthetic or natural
Examples of synthetic organic fertilizers
urea formaldehyde (UF) and isobutylidene diurea (IBDU)
Examples of natural organic fertilizers
manure, sewage sludge, fish hydrolysates, blood, and bone meal
Advantage of organic fertilizers?
They must be converted to inorganic ions before absorption, therefore they are not leached as readily from the soil
Advantage of inorganic fertilizers?
The solubility is less affected by temperature
slow release fertilizers
fertilizer that is at least 50% water-insoluble nitrogen (WIN), rate of release may vary depending on soil moisture and temperature; release nutrients (nitrogen) over an extended period of time which reduces the amount of nutrients that may be leached and also reduces salt and fertilizer burn problem
fertilizer “burn”
injury to a plant resulting from excess fertilizer salts in the surrounding soil
Example of slow-release fertilizer
sulfur-coated urea; has a coating that breaks down slowly to release the inner fertilizer over an extended period of time
water-insoluble nitrogen
WIN; nitrogen fertilizer in a form that is not readily soluble in water
What rate should fertilizer be applied?
Dependent on the tree (age, health, and species), form of the fertilizer, method of application, site conditions, and the goal to be achieved; create a fertilizer prescription based on foliar, soil, and pH analysis
How much supplemental nitrogen is needed?
General recommendation for slow-release fertilizers is 2-4 pounds of actual nitrogen per 1,000 square feet of root area; for quick-release fertilizers is 1-3 pounds of actual nitrogen per 1,000 square feet per application
cation exchange capacity
CEC; ability of a soil to adsorb and hold cations; affected by soil pH; measures soil fertility, clay composition, and engineering characteristics
What frequency should fertilizer be applied?
Dependent on the tree, soil conditions, and fertilizer type
Clay soils have a high cation exchange capacity (CEC), what does that mean?
Clay soils readily attract, adsorb, and exchange positively charged minerals; less possibility of leaching
surface application
placement of fertilizer or other material on the ground surface; broadcast; fertilizer is applied over the soil surface using a spreader with dry formulations or sprayer with liquid formulations, calibrated to apply the desired amount of nitrogen per 1,000 square feet
Advantages of surface fertilizer application?
requires the least amount of time for application, does not require sophisticated equipment, delivers nitrogen to the upper surface and if there is enough water applied it may penetrate into the upper 6 inches of soil, where most of the trees actively absorbing roots are located
volatilization
conversion of a solid or liquid into a gas or vapor
Disadvantages of surface fertilizer application?
potential for volatilization or runoff into nearby rivers and streams, which contaminates the water
subsurface application
placement of fertilizer or other material below the soil surface; designed to place fertilizer below the majority of the turfgrass roots
drill-hole method (of fertilization)
applying fertilizer by drilling holes in the soil within the root zone; uses granular fertilizer; drill holes 2-4 inches in diameter spaced 12-36 inches apart around the tree in concentric circles or in a grid pattern; begin holes several feet out from the trunk to avoid damaging the buttress roots and extend holes to the drip line
drip line
imaginary line defined by the branch spread of a single plant or group of plants
liquid injection fertilization
applying liquid formulations of fertilizer by injection into the root zone of a tree; uses fertilizer dissolved or suspended in water injected under hydraulic pressure using a soil injector; focus application in the upper inches of the soil
foliar application fertilization
applying a fertilizer, pesticide, or other substance directly to the foliage; used to correct minor element deficiencies
chelate
chemical compound that keeps plant nutrients [usually iron (Fe)] soluble and available for plant absorption over a broad range of pH
chelated iron sprays
used to provide rapid, although temporary, treatment of iron chlorosis; method not efficient for introduction of other essential elements, such as nitrogen
When are micronutrient spray applications most effective?
Just before period of active growth
implants
device, capsule, or pellet inserted into the tree’s xylem system to treat or prevent diseases, disorders, or pest problems; requires a relatively large diameter and deep hole in the trunk; rely on transpirational stream to move materials systemically within the xylem; used to treat minor micronutrient deficiencies
injections
method of putting a liquid fertilizer or pesticide directly into the soil or plant’s tissues; rely on transpirational stream to move materials systemically within the xylem; used to treat minor micronutrient deficiencies
Where to place implants or make injections?
Below the bark and cambium, directly into the first two rings of the xylem; do not reuse injection wounds from previous applications
Long-term benefits of organic mulches?
improved soil structure, increased water and nutrient-holding capacity, and improved aeration and water infiltration
salt index
relative scale (compared with sodium nitrate) on some fertilizer labels that indicates the likelihood to cause burning
reverse osmosis
a phenomenon in which water is “drawn out” of the roots because the concentration of salts within the surrounding soil is greater than the concentration of solutes (salt) in the root due to excessive fertilization without proper irrigation; causes root “burn”
How to minimize leaching?
apply only the amount of fertilizer needed, use organic or slow-release forms, and avoid over irrigating sandy soils; otherwise leached nutrients can also pollute groundwater, lakes, and streams
How does pH limit the uptake of certain elements?
Soil pH can influence solubility of certain elements by causing them to form insoluble salts
prescription fertilization
philosophy of basing fertilization recommendations on plant needs, which are primarily determined by soil or tissue testing; requires laboratory analyses of the soil and leaves to determine the nutrient needs of a tree
soil analysis
analysis of soil to determine pH, mineral composition, structure, salinity, and other characteristics
foliar analysis
laboratory analysis of the mineral content of foliage; must account for seasonal and species fluctuations in foliar nutrient content
texture analysis
determines the amount of sand, silt, and clay present in the soil; useful in assessing the physical characteristics of the soil