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Making sure your lawn receives the proper nutrients is an important part of lawn care.

A key component of lawn care is providing the lawn with the nutrients it needs to grow.  Each nutrient is involved in different plant processes.  Nutrients are loosely grouped into two categories:  Macronutrients and micronutrients.  The nutrients listed under Macronutrients are almost always in lawn fertilizers.  Potassium, calcium, magnesium and sulfur are sometimes categorized as macronutrients, and other times as micro-nutrients.  Each has its specific function in plant growth and development.

Macronutrients

• Nitrogen
• Phosphorous
• Potassium

Micronutrients

• Calcium
• Magnesium
• Sulfur
• Iron
• Manganese
• Copper
• Zinc
• Boron

Lawn Fertilizer Analysis

Most lawn fertilizers contain the macronutrients, or what you could call “the big three:” Nitrogen (N), Phosphorous (P), and Potassium (K).  The fertilizer bags have their N-P-K analysis, or numbers that tell consumers how much of each nutrients is in the fertilizer, by percentage.  This can also tell you how many pounds of active ingredient are in each type of fertilizer.  For example, a 10-10-10 fertilizer has the same percentage of each ingredient.  100 lbs of the fertilizer would have 10 lbs of each active ingredient.  Here’s what each of the “big three” do for plants:

Nitrogen:  The basis of all protein and DNA.  Used mostly for growth.  Nitrogen application is said to “green up the grass” because it is incorporated into the leaf tissue.

Phosphorous:  This nutrient plays an integral part in photosynthesis, energy transfer and flower/fruit growth.  Plants without enough phosphorous do not produce many fruits, and their seeds can be deformed or not fully formed.

Potassium:  Many processes within the plant use potassium.  Sugar movement, cell division, root development and water retention all require potassium.

Micronutrients are just as Important

Even though most fertilizers contain only Nitrogen, Phosphorous and Potassium, the micronutrients are just as important for healthy plant growth, and lawn grass will show the affects of an imbalance, or too little of any of these nutrients.

Calcium:  Plants without enough calcium have thick, woody stems and poor root development.  Lack of calcium can give the grass a yellowish hue.  The ratio of calcium to magnesium must be 7:1 for proper plant growth.

Magnesium:  Chlorophyll is partially made of magnesium, and needs this nutrient to function.  Too much Potassium in the soil can prevent magnesium from being present in the soil in a form that is available to plants.

Sulfur:  proteins have sulfur components in them.  Peppers, onions, cherries and plums need plenty of sulfur to bloom and produce good fruit set.  Many lawn grass fertilizers have a sulfur component.

Iron:  Iron uptake is affected by the amount and form of manganese.  Iron can bond tightly with soil particles.  Addition of a light layer of compost raked into the grass can re-introduce iron into lawns where it is deficient.

Manganese:  Plants require manganese to oxidize enzymes.  Acid soils (lower pH) tend to make more manganese available than alkaline (high pH) soils.

Copper:  Copper is a catalyst for specific enzymes within plants.  Many plant growth processes rely on sufficient copper.

Zinc:  Protein and starch building processes require zinc.  Too much Phosphorous in a lawn can bind up Zinc and make it unavailable to plants.

Boron:  Flowering, fruit and seed formation are affected by boron.

Identifying Specific Lawn Nutrient Needs

Before applying fertilizer to the lawn, it is always a good idea to have a soil test done.  You can pick up soil test boxes at your local cooperative extension office, along with instructions about how to collect a representative sample and prepare it for testing.  Fertilizer is expensive, and over-use of nutrients can cause pollution.  Getting a soil test will ensure that you are supplying your lawn with the right nutrients in the right amounts for healthy growth.

Source: http://www.ctahr.hawaii.edu

Plants need balanced nutrition to thrive, just like people.  One of the important nutrients for plant growth and development is Potassium (K), which is a component of most standard lawn fertilizers.  To use Potassium fertilizers correctly, it is important to understand how Potassium functions in plants, and how to recognize the signs of Potassium deficiency.

Potassium in Fertilizer

Potassium is one of the “big three” nutrients found in most lawn fertilizers.  Most fertilizer analysis gives the N-P-K number, which indicates what percentage of each nutrient is in the fertilizer.  The percentage of Potassium is indicated by the last number in the N-P-K analysis.

Potassium Function in Plants

Potassium is integral to many growth processes in plants, including:

• Photosynthesis
• Starch and protein production
• Enzyme reactions
• Water movement
• Protein synthesis
• Cell wall components
• Fruit development

Recognizing Potassium Deficiencies

(See above picture.)

Potassium deficiency is a serious problem for all plants, because it is involved in so many different plant processes.  Plants experiencing potassium deficiencies will show the following symptoms:

• Yellowing and curling of edges of lower (older) leaves
• Sometimes leaves will turn purple
• More likely to occur in times of drought stress
• Leaf edges looked burned

There are a number of things that can cause potassium deficiency.  Sandy soils tend to be more deficient in potassium, because it is leached easily from soils that do not have a high CEC (Cation Exchange Capacity).  Adding organic matter to the soil can help in potassium retention.  Soils with a low pH (acidic soils) sometimes have enough Potassium, but it is not available to plants.  It is important to test the soil pH to see if the potassium is there, but not available.

Correct Application of Fertilizers

Many soils are deficient in Potassium, but it is always a good idea to look at the soil test before adding any fertilizer.  Flowers, fruits and vegetables need more potassium fertilizers during flowering and fruiting.  General lawn fertilizers will usually have a balanced analysis, and will have enough Potassium for the average lawn, unless the soil is severely depleted or the pH is off.  Apply potassium fertilizers that are balanced with Nitrogen and Phosphorous, and your soil will receive its necessary requirements to support plant growth.

Nitrogen is a nutrient that all types of grass need. If nitrogen levels are low try using nitrogen fertilizer to help you lawn return to a healthy state.

Grass is notorious for needing a lot of nitrogen fertilizer.  Nitrogen is a macronutrient that all plants need.  It is the basis for proteins in plants and animals, and is present in the chloroplasts, which are the molecules within plants that perform photosynthesis, making food for the plants.  If plants do not have enough nitrogen, they turn yellow, in part because the chloroplasts are not functioning properly. Some plants require more than others.  Most species of grass are what are called “heavy feeders” and require a lot of nitrogen.  You will often hear people say their lawn has “greened up” after an application of fertilizer.  After fertilization, the nitrogen levels in the plants are higher, including inside the chloroplasts, hence the greener color.

Forms of Nitrogen Fertilizers

Organic nitrogen is found in decaying plant and animal material.  This is why compost is a good addition to soil.  Commercially synthesized nitrogen generally includes either nitrate or ammonium.  In the form of nitrate, plants can quickly and easily absorb nitrogen, but it leaches, or is washed, from the soil quickly.  The ammonium form bonds tightly with soil particles, so it moves through the soil to plants more slowly.  To provide your lawn with the nitrogen it needs, use fertilizers that have both forms of nitrogen, or alternate applications of each type.

Organic forms of nitrogen are beneficial to the lawn, but take longer to break down and become available for plants.  Inorganic forms such as nitrate or ammonium are more quickly available to plants, but can be lost into the groundwater, causing pollution problems downstream, if not applied correctly.

When to use Nitrogen Fertilizer

“More is better” is not the name of the game when fertilizing a lawn.  To much of a good thing is not, in fact, a good thing, when it comes to fertilizer.  Over-fertilized plants produce soft, weak growth.  When more nitrogen (or any nutrient) is added to the soil than can bond with the soil, it will move through the soil, and can cause imbalances away from the site it was added.  Many factors affect the ability of plants to take in nutrients.  Weather, soil pH, plant type, and stage of growth all influence the way plants take in and use nutrients.

Each species of grass has different fertilizing requirements.  Usually, nitrogen fertilizer also includes phosphorous and potassium.  These formulations are called “N-P-K” fertilizers.  The ratio of each nutrient to the other is indicated by a number.  This is called the “fertilizer analysis.”  You could buy a 10-10-10 fertilizer, which has equal parts of each nutrient.  A 20-10-10 would have twice as much nitrogen as phosphorous and potassium.  The numbers also correspond to percentage by weight in the particular fertilizer.  A 10-10-10 fertilizer is made of 10% of each nutrient.  The additional 70% of ingredients are inert, or inactive.  A higher number corresponds to a larger amount of active ingredient in the fertilizer.

Nitrogen is important in overall plant health. Phosphorous is integral in root formation.  Potassium regulates water movement.  If you are just establishing a lawn, you might want to use fertilizer that has more phosphorous by percentage than nitrogen or potassium, so the plants can establish a healthy root system.  During the summer, when the grass is actively growing, you may want to use a fertilizer with more nitrogen.  Always apply nitrogen fertilizers at the rate recommended for your growing conditions and the species of grass that you grow.  A plant can only use so much fertilizer.  Any excess will be waste-in terms of money spent, and in terms of a resource that is underutilized.  Nitrogen, in particular, is harmful when over-applied, as extra nitrogen will seep through groundwater, into streams and continuing to rivers causing algal blooms and other environmental impacts.

Nitrogen fertilizer is an important part of a lawn maintenance plant.  When applied in the proper form at the proper time, it will help maintain a lawn in peak condition.