FERTILIZING YOUR LAWN
Everyone wants a healthy lawn and though lawns gets nutrients from the soil they often need a little help during the growing season. Fertilizer can help your lawn stay healthy, encourage leaf and root growth, reduce troublesome weeds, aid in recovering lost nutrients and help the lawn recover from numerous activities.
Fertilizers are organic or inorganic materials that are applied to the soil or the plant to improve its health and provide sufficient mineral nutrient elements. Plants obtain three of the essential elements they need for growth - carbon, hydrogen and oxygen - from water and the carbon dioxide in the air. The other nutrients plants need are found in the soil and absorbed by the plant’s root system. These nutrients are grouped into two categories, macronutrients and micronutrients.
There are three main macronutrients – nitrogen (N), phosphorus (P) and potassium (K).
- Nitrogen promotes rapid growth, leaf development, chlorophyll formation and protein synthesis.
- Phosphorus plays a key role in early root growth, hastens maturity, stimulates blooming and aids seed formation.
- Potassium increases resistance to drought and disease and also plays a part in root growth as well as in stem development.
You will find the NPK content in the description printed on the front of bags of fertilizer. The description may not expressly say "NPK" (it may simply be implied), but you will at least see a series of three numbers, which correspond, respectively, to the nitrogen, phosphorus and potassium content of the fertilizer. They are always listed in that order.
Along with N, P and K, any of the other nutrients contained will be listed on the fertilizer label. The numbers shown for each nutrient give the percentage, by weight, of that nutrient compared to the total contents of the bag.
Macronutrients are essential for plant growth and needed in relatively large amounts by plants. NPK are among the macronutrients along with calcium (Ca), magnesium (Mg), and sulfur (S).
Micronutrients also are essential for plant growth, but are needed in minute amounts. The micronutrients are: boron (B), copper (Cu), iron (Fe), chloride (Cl), manganese (Mn), molybdenum (Mo) and zinc (Zn). The fertilizer may contain some of these other nutrients, as well as NPK. You’ll find a more detailed breakdown of the fertilizer’s contents on the fertilizer label.
The two most important pieces of information here are the guaranteed fertilizer analysis and the type(s) of nitrogen the fertilizer contains.
The types of nitrogen listed indicate which are a quick-release or a slow-release form of N. Along with N, P and K, any of the other nutrients contained will be listed along with the numbers that give the percentage, by weight, of that nutrient compared to the total contents of the bag.
Fertilizers – Quick-Release and Slow-Release Nitrogen
What's the difference?
There are two basic types of nitrogen sources contained in lawn fertilizers – slow-release and quick-release – and it’s important to know the pros and cons of both.
Quick-release nitrogen in fertilizers is useful because the nutrients are immediately available to plants. This water-soluble nitrogen (WSN) becomes available when it is dissolved in water, either through irrigation or rainfall, when it is applied. There are several benefits of quick-release fertilizers - nutrients are immediately available to plants and they stimulate quick shoot growth and greening.
On the down side, they rapidly deteriorate from the soil through the leaching of nitrates; they last only two to four weeks; and if they are over applied they can cause burning to the grass plant.
There are several benefits of slow-release nitrogen in fertilizers. They provide more uniform grass growth. They are less likely to burn the lawn or other plants. They can last 6 to 8 weeks or longer so they don't need to be applied as frequently as fertilizers with quick-release nitrogen.
On the downside, nutrients are not immediately available to plants. They are generally more expensive per pound than quick-release fertilizers. They may not work as well in cold soil. They require heavier irrigation during periods of high temperatures and too much irrigation may speed-up the release of nutrients.
The fertilizer bag will include details on when and how to apply the product.
Apply the fertilizer with either a drop or broadcast spreader.
A drop spreader delivers the fertilizer to the lawn through an opening at the bottom of a spreader hopper. The fertilizer is evenly spread across the width of this opening.
A broadcast spreader has a spinning device just below the opening at the bottom of the spreader hopper. Fertilizer is spread across a wider area of the lawn by the rotary action of the spinning device.
Each type spreader will have an application dial or other device that allows you to set the amount of fertilizer that moves through the opening.
As you make the application, be sure to position each pass with the spreader so there are no gaps or excessive overlaps in the fertilizer distribution pattern. You want to apply the fertilizer evenly over the entire surface of the lawn.
To help assure more even and thorough coverage, the fertilizer bag also may include spreader settings to split the recommended amount of fertilizer equally between two, half-rate applications.
In this case, adjust the spreader application dial to distribute one-half of the fertilizer bag’s recommended rate. Make the first application in a north to south pattern, covering the entire lawn. Begin the second application immediately, in an east to west pattern to cover the entire lawn.
If you purchased more fertilizer than you need, store the unused portion in a sealed container in a cool, dry place. If properly stored, it will be just as effective even one year later.
If you have questions about how to properly apply the product with the type of lawn spreader you will be using, ask the specialist at your garden center before making your purchase.
It’s important to note that not all grass varieties have the same nutrient requirements, and you can sometimes do more harm than good when applying fertilizers arbitrarily.
A soil test is recommended to identify the precise needs of your lawn. The soil test will include your soil P and K and other nutrient levels, along with other factors important to the health of your lawn, such as acidity or alkalinity (pH) and Cation Exchange Capacity (CEC). Though soil testing for N levels is possible, such testing is seldom conducted as those levels change quickly. A soil test also can provide a fertilization recommendation based on your turfgrass species.
Always read the label on the fertilizer container and follow the instructions provided.