An easy thing to spot will be the lower leaves in these plants will appear yellow. You may also find it hard to grow plants as root systems with a lack of nitrogen may not provide the support needed for healthy new growth. Excess nitrogen burns the grass by scorching the plant tissue resulting in large dead patches in your lawn shortly after fertilizing. This is where slow vs quick-release fertilizer comes into consideration.
Just remember to always read and follow the instructions on the label of products you purchase as too much nitrogen can have disastrous effects. How much is too much? According to Cornell University , you should never apply more than one pound of available nitrogen per 1, square feet at one time. Most lawn care experts will recommend that using slightly less fertilizer than you need is much safer than overusing too much. The first step before applying any product to your lawn is understanding what you are actually using.
This starts with figuring out what those numbers on the front of the fertilizer bag or bottle mean. This is the fertilizer grade. The first number indicates the percentage of nitrogen in the fertilizer, the second number is the percentage of phosphorus and the third is the percentage of potassium.
Many simply call this series of numbers the N-P-K. These fertilizers are considered straight fertilizers, as they only contain nitrogen. Along with having different ratios of nutrients some fertilizers are made from different source ingredients. There are many sources of nitrogen including various organic and inorganic materials.
Inorganic nitrogen fertilizers are made from mineral sources and contain high levels of nitrate. The most common options include:. The soil absorbs the nutrients fast, but there is a greater risk of burning the lawn unless there is the proper ratio of slow to fast release nitrogen in place. The nitrates also pass through the soil rapidly, producing quicker results for those in a pinch. We typically recommend homeowners do their best to stay away from these types of products and opt to use some form of an organic fertilizer.
Reason being organic fertilizers are typically safer to use and better for the environment. They recommend the application of 2. The label on the fertilizer bag is required to show the percentage by weight of nitrogen, available phosphate commonly referred to as phosphorus and sulfate of potash commonly referred to as potassium :.
Nitrogen, phosphorous and potassium are also sometimes referred to as N-P-K. To understand how much of each nutrient is being applied to your lawn, you must multiply the weight of the fertilizer bag by the percentage of each nutrient. For example, a 30 lb. Take the total pounds of nitrogen in the bag and divide by the number of thousands of square feet the bag covers.
Since we have already calculated 7. For the 5, sq. So, applying 7. There is no one perfect or absolute best fertilizer to purchase for your lawn, but there are many good ones available. Nitrogen is the most important nutrient; percent nitrogen is expressed as the first number in the series of three on the fertilizer bag.
What kind of nitrogen in the product is the key information, as there are fast-release and controlled-release nitrogen sources. To find the answer, look in the guaranteed analysis section on the back of the bag. Key terms to look for include controlled-release, slow-release, slowly-available, or water-insoluble nitrogen.
Some specific types that may be listed include ureaform, sulfur-coated urea, polymer-coated urea, and IBDU isobutylidenediurea. Several organic nitrogen sources are controlled-release. Most quality lawn fertilizers offer a balance of fast and controlled release sources to offer a fertilizer that will provide some quick color without a big surge of growth and some long-lasting nitrogen.
The high percentage of nitrogen by itself is not a problem, assuming the amount put down on the lawn is adjusted accordingly. The higher the percent nitrogen, the less product is needed on the lawn to supply the one pound per 1, square feet rate suggested.
In addition, if the material is controlled-release, the risk of burning the lawn is low even though the percentage nitrogen in the product may be high. Balanced fertilizers, such as a , have a N:P:K ratio of The reason these are not suggested for repeated use on lawns is the amount of phosphorus applied, when supplying the one pound of nitrogen per 1, square feet, becomes quite high. Excess phosphorus may lead to potential runoff problems and more weeds in the lawn.
Also, many of the all-purpose balanced fertilizers have only fast-release nitrogen as the nitrogen component, so the risk of burn may be higher. Whether a fertilizer is organic or synthetic, after applied to the lawn it must convert to a form the plant can use. Once converted, the plant does not know the difference as to the nitrogen source. Nitrogen promotes vigorous grass growth and attractive green color. Where nitrogen is lacking, grass becomes pale and thin, with slowed growth and increased vulnerability to some diseases.
Phosphorus is important for root growth and early plant vigor, while potassium regulates physiological processes in the grass plants and permits more efficient use of nitrogen. In general, Clemson Cooperative Extension Service says fertilizers with , or or similar ratios supply nitrogen, phosphorus and potassium in the correct proportions for healthy grass growth. For example, a fertilizer contains the three primary macronutrients in a ratio and is a suitable selection for lawn application.
Whatever the NPK number or percentages of nutrients by weight you select, the quantity of product that should be applied is based on supplying the grass with nitrogen at the correct rate.
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