Fertilization Formulations Flashcards
Nitrogen Form (Synthetics):
By nature, synthetic fertilizers are salts with high water solubility and are characterized by a limited residual response. It is critical to recognize that fertilizers are salts. It is said that plants absorb only about 0.15 Kg of Nitrogen in any one application. As soon as the synthetic fertilizers are dissolved in solution, they are immediately available to the plant and are subject to leaching with the water they are dissolved in. Water is, therefore, the release mechanism. The fertilizers dissociate into their respective ions in solution
Nitrogen Blends:
Urea: 46-0-0
Anhydrous ammonia 82-0-0 (extremely dangerous)
Ammonium Nitrate: 34-0-0 (restricted in Canada in 2008)
Ammonium Sulfate 21-0-0-21 (additional of Sulphur, lowers pH)
Synthetic Slow Release:
Coated synthetic fertilizer in order to slow down the dissolving of nutrients and subsequent uptake by plant roots. At times, manufacturers will also blend the slow release with some immediately available synthetic fertilizer. In these cases, a percentage will be noted on the bag such as “75% PCU, 15.75% S, Fe, Mn, Cl”. This indicates that 75% of the contents are slow release (poly coated urea), with 15.75% being secondary nutrients that are immediately available, and the rest being inert filler.
Slow Release Nitrogen:
Water insoluble nitrogen: require microorganisms for decomposition.
Slowly soluble nitrogen: requires a constant presence of water.
Coated Fertilizers: As the coat cracks or is infiltrated by water, the nutrients are released. One example of a coated urea is Sulfur Coated Urea (SCU).
A newer technology in slow release fertilizers is Poly Coated Urea (PCU).
Organic Fertilizer:
The oldest method of fertilization in existence is the use of organic fertilizers. At the base of it, “Organic” simply means that it contains carbon, so there are many potential sources of organic fertilization. One of the obvious sources of this would be compost derived from animal waste or decomposed plant material. Other sources include peat moss, sewage sludge, dried blood or bone meal, rock powders, seaweed, diatomaceous earth, and mycelium inoculants. In golf courses, zeolites are often used to increase CEC of the sand without changing the structure of the mineral soil. These fertilizers require soil microorganisms to process the minerals in their natural states, and cannot be made available to plant roots in solution without appropriate temperatures, aeration, and moisture.
Fertilizers and Growth Cycles:
warm season and cool season grasses. In Alberta, the grasses used in turf applications are cool season grasses. As you can see in the diagram below, there are two natural peaks in growth and two natural dormancy periods in cool season turf. We noted in the identification module that Kentucky Bluegrass was particularly sensitive to the mid summer lull. When people see their grass turning brown in the heat of summer, they often immediately default to fertilizing. If the problem is the heat, and a lack of water necessary to cool the plant, then adding a salt based fertilizer will almost certainly exacerbate the problem.
Cold Season Grass:
As the weather warms to about 10 °C, the root system begins to deepen. With a deepening root system comes more access to moisture and minerals and vegetative growth increases as well. More vegetative growth, in turn, means more photosynthetic carbohydrate production and the plant as a whole gains vigor. As the weather warms, the cool season grasses are no longer in their peak growing conditions and the plant goes into a period of partial dormancy.
Bedding Plant Fertilization:
Fertilization practices for bedding plants will vary from that of the turf because their growth cycles more closely follow the Warm Season Turfgrass model of slowly gaining traction through the early summer, peaking when they are in full flower, and then eventually declining toward the Fall Frost.
Prior to purchase, the growers will have maximised growth in order to bring their product to market faster and have it looking as good as it possibly can. If the grower is a reputable one, they will taken measures to harden off bedding plants prior to sale in late spring
Time of Year and Nutrient Balance:
Light levels vary widely with the seasons. Fertilizer programs should consider the intensity of light reaching the crop and balance the nutrient application accordingly. If the plant is growing under very high light levels, it will tend to use a significantly higher quantity of fertilizer. This extra light stimulates photosynthesis and the production of more plant tissues, which will then require more fertilizer. Note that photosynthetically optimal air temperatures are 18-27 degrees C. In the summer, the grower can use large quantities of nitrogen because the plant is effectively using it. In the winter, lower light levels will find plants in a period of reduced growth unless the grower inputs significant artificial light and heat. Because of this, the plants may be stressed and more susceptible to disease and insect pests. To help offset these problems, potassium should be increased in these times, relative to nitrogen
Growth Cycles
Germination
Vegetative Growth
Maturation
Reproduction
Fertilizer: Rule of Thumb
Growing Season/Vegetative (Spring/Summer): 3:1:2
Hardening/Maturation (Fall): 1:2:3
Germination (Early Spring): 2:3:1
Fertilizer Requirements:
N Fertility Level Kg N per 100m2 / GM Turfgrass Species
Low 0.1-0.25 CRF
Medium 0.1-0.5 TF, PR
High 0.25-0.75 KB, AB, CBent
