Just as humans need vitamins and minerals to maintain healthy bodies, grass requires various nutrients in which to grow healthy and strong. In fact, grass needs a minimum of 16 micro- and macronutrients for proper development. If it lacks any of these vital nutrients, the grass will not grow or develop as well as it could, leading to bald spots, brown patches and thinning throughout the landscape. These 16 nutrients include:
Grass always has plenty of carbon, hydrogen and oxygen as these nutrients are available through the air and in the water. However, it can never get enough calcium or magnesium. It may also need higher quantities of nitrogen, phosphorus and potassium – nutrients that aren't readily available without fertilization.
Every nutrient plays an important role in turfgrass development. For example, nitrogen helps the grass to resist diseases and to tolerate stresses while affecting its density, growth and color. Iron is important for photosynthesis and chlorophyll formation, and phosphorus affects root growth and maturation. Potassium is also important as it helps the grass to build a tolerance for cold weather, droughts and diseases.
Because grass can't get certain nutrients from the environment, it may not reach its full potential for color, thickness and hardiness. Fertilizer helps to fill in the gap, to boost turfgrass development and to maintain the lawn's health over time. It contains three important nutrients for growth: nitrogen, phosphate and potassium. These nutrients help the grass to thrive and to grow strong and vibrant while resisting traffic, pests and other stresses.
Fertilizers come with varying amounts of nitrogen, phosphate and potassium, so it's not recommended to purchase just any bag and to start applying it on the grass. The amount that's required on any particular grass depends on a few factors:
As mentioned in the previous section, fertilizers contain three main nutrients to improve turf growth and development: nitrogen, phosphate and potassium. These nutrients show up on the package in the form of three numbers. For example, a bag may have the numbers 20-5-10 on the front label.
Each number represents the percentage of the three main ingredients. So if a label reads 18-24-12, it contains exactly 18 percent nitrogen, 24 percent phosphate and 10 percent potassium in that order. The label may also include other micro- and macronutrients with their respective percentages. Nitrogen fertilizers are characterized by the speed in which they release nitrogen to turfgrass and plants.
Quick-release fertilizers supply the plants with nitrogen in just a few days and cause quick growth and color response. Because they have a higher nitrogen percentage, they work quickly and require less handling. They have numerous benefits but require special care to avoid damaging the turf and ornamentals.
Slow-release fertilizers gradually release nitrogen to the plant by way of microorganism breakdown. They contain either chemically stabilized nitrogen or a water-soluble or water-insoluble nitrogen that has a coating, which restricts solubility of the fertilizer.
Not everyone applies fertilizer at the most opportune time. In fact, people often apply it only when it fits their schedule and not when the conditions or the timing is right. Nitrogen is subject to environmental losses such as leaching to groundwater and denitrification, a process in which bacteria reduce nitrate and produce nitrite, nitric oxide or nitrous oxide.
Controlled-release means the same as slow-release and is used interchangeably. It's also possible to hear the term delayed-response when reading about fertilization. The preferred term for all of these products is fertilizer technologies.
One of the many fertilizers and plant growth regulators at Pedchem.
Fertilizer technologies are separated into three categories: uncoated, coated and bio-inhibitors. Each one has a special way of providing nitrogen through a controlled-release method:
Coated, controlled-release fertilizers use polymer, sulfur coatings or a combination of the two in order to deliver nitrogen to the plant.
Bio-inhibitors are not truly classified as slow-release fertilizers but do somewhat slowly release available nitrogen to the soil. They contain chemicals that cause microbes to convert the nitrogen to plant-available forms. This microbial process makes the nitrogen susceptible to environmental losses but also results in an increased availability to the plant. Bio-inhibitors come in two different types: urease and nitrification.
Urease inhibitors kill the soil enzyme known as urease. By inhibiting this enzyme, the urea will not decompose as quickly and will have a chance to move farther into the soil through rainfall. It's important to control volatilization and to incorporate the urea into the soil. If measures are not taken, it can result in as much as a 20 percent nitrogen loss.
Urease inhibitors have several benefits, such as being added to UAN, a urea-ammonium nitrate solution. They can also be added to urea and may inhibit the soil enzyme for two weeks or more depending on the conditions. However, warmer temperatures may cause the urease to repopulate more quickly, thus shortening the control.
Nitrification inhibitors slow the denitrification process by bacteria in the soil. They prevent ammonium-nitrogen from converting to nitrate-nitrogen and reduce overall environmental losses due to leaching. These inhibitors keep the nitrogen in a special form that isn't easy for the plants to absorb. They delay the conversion for up to four weeks depending on the temperature and the soil's pH.
It's not always easy to decide on a fertilizer to use with so many different blends available. In many cases, choosing a slow-release fertilizer will make the most sense and help to prevent burn while achieving positive results over time. With that said, making the choice comes down to two options: granular and liquid. Some of the more common granular slow-release nitrogen sources include:
Many different liquid nitrogen products also exist on the market and provide just as effective results, including:
Developing an annual fertilizer program comes down to a few things: the type of turf, the level of desired quality, the number of applications per season and the application technique.
With so many different grasses and plants in a yard, it's easy to see why there's a mass production of unique fertilizers. Not all fertilizers are the same, which is indicated by the numbers on the label. Each fertilizer has a different percentage of nitrogen, phosphate and potassium for specific uses. A fertilizer that may work great on new sod may severely damage mature grass. It's important to identify the turf, to understand the differences and the needs of cool- and warm-season grasses and to use the appropriate fertilizer for the situation.
The difference between a good lawn and a high-quality lawn is the work that's put into it. A good lawn may only need one application per year. The clippings can be returned to the stand, and the grass may never require irrigation. A high-quality lawn is irrigated and mowed regularly. It may also receive pesticide treatments and up to two or three fertilizer applications per year.
Lawns don't benefit from overfertilization. Too much fertilizer can kill the grass; too little can have no effect whatsoever. As a rule of thumb, never apply more than a pound of nitrogen in a 1,000-square-foot area. Whereas some people fertilize in the fall, others fertilize their lawns in the spring and the summer. For example, those who have Kentucky bluegrass can fertilize in April or May to have a vibrant lawn in the winter. It's also possible to apply fertilizer in the fall. It all depends on the grass, the location, the site conditions and the overall quality expectations.
Having options doesn't always make a decision easier, and the debate between liquid and granular fertilizers has a history. It's really a matter of choice and the effects that one hopes to achieve through fertilization. Liquid fertilizers offer several benefits, such as providing immediate results as the plants can easily take in the solution. However, liquid fertilizers have to be applied more frequently, may cause burning and can leach deep into the ground, resulting in loss.
Granular fertilizers don't have to be applied often. Just one application can provide up to nine months of residual absorption. The effects may not show up right away, but there's a low risk of burning the turf. The slow uptake may not help the turf to recover from any nutrient deficiencies, and the granules will need constant watering to work effectively.
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