What is NPK Fertilizer?
What does NPK mean? When you’re looking at grass fertilizer, you’ll see a series of three numbers separated by dashes on the label. All fertilizer labels are required to provide their nutrient content. That means the amount of Nitrogen fertilizer, Phosphorus fertilizer, Potassium, and micronutrients. N-P-K stands for Nitrogen, Phosphorus, and Potassium, and is expressed as three numbers that give the percentage (also called “ratio”) of each nutrient by weight.
Nitrogen Liquid Fertilizer
Nitrogen is the nutrient used in the largest quantity by plants, and is a key driver for greenness and leaf growth. If you’re looking to support growth, you should apply a Nitrogen liquid yard fertilizer, ensuring that the first number in the fertilizer is higher as long as your lawn is not suffering from pests, disease, or other ailments.
Phosphorus Lawn Fertilizer
Phosphorus helps regulate plant metabolism, is stored in seeds as phosphorus reserves called phytin, and buffers cell pH to maintain internal equilibrium. With all these essential processes and molecules with which phosphorus is associated, you’re probably halfway out the door to go apply some to your lawn right now, but not so fast.
Phosphorus is best applied in certain situations, including seeding or turf establishment, or if a soil test indicates a deficiency. In some states, phosphate applications are not permitted unless establishing a new lawn or unless your soil test indicates a deficiency.
Potassium Grass Fertilizer
One of the more recognized roles that potassium plays is its regulation of the opening and closing of plant stomata, or the tiny holes in the leaf surface that allow gas exchange. When potassium levels are sufficient, the plant can keep its stomata tightly closed during times of drought to prevent moisture loss. This reduction of respiration allows the plant to preserve much-needed energy during times of stress.
Soil Testing to Figure out What Liquid Yard Fertilizer to Apply
Soil testing your yard or lawn is the best way to understand what nutrients are in your soil. Soil quality varies significantly depending on your location, soil type, and more. Soil tests measure the nutrients available to your grass. Soil nutrients fluctuate throughout the growing season due to lawn growth, fertilizer, mulch, leaching, water, and weather. A soil test will determine the current status of your lawn.
There are several reasons why you should do a soil test:
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It gives you pH levels so you can correct them to unlock nutrients in the soil (Ideal lawn pH should be 6.0 - 7.0).
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Identifies if and which lawn care nutrients are needed.
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Responsible lawn care, preventing over-application of nutrients.
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Saves time, money, and frustration by identifying the root causes of your grass’s health (or lack of).
When our lawns are struggling, we may buy fertilizer or grab the hose to water the lawn. Many times, the problem is deeper than the blades of grass, though. A soil test gives you valuable information about the best way to care for your lawn and will identify why your lawn maintenance regimen might not be working.
Organic vs. Synthetic Liquid Lawn Fertilizer
Organic fertilizers contain carbon molecules and are derived from plant and animal matter. This matter, available from a variety of sources such as shale, manure, manufacturing waste, etc., contains plant nutrients that are bonded to carbon. When the fertilizer is applied, the nutrients separate from the carbon molecule or molecules and are absorbed by the plant. This first step is necessary as plants can’t directly uptake nutrients that are bound to carbon.
Synthetic fertilizers are the mined products of naturally occurring mineral deposits. They usually contain fewer quantities of nutrients that are in greater concentrations (OSU). Potassium chloride, the most widely used potassium fertilizer, is a naturally occurring salt that contains greater than 50% potassium. It can be applied on its own, or it can be combined with other nutrients through a manufacturing process. Many popular nitrogen fertilizers are produced via the Haber-Bosch process, which combines hydrogen atoms with nitrogen derived from the atmosphere to produce ammonia.
Granular vs. Liquid Fertilizer
Liquid Fertilizer
Liquid lawn fertilizer is a liquid concentrate of nutrients for your lawn. This concentration is added to water to create a nourishing solution of food for your plants and grass. It is a fast-absorbing way to fertilize your lawn and plants.
Granular Fertilizer
Granular lawn fertilizer is fertilizer known as dry pellets or solid fertilizer. As a solid, this fertilizer is scattered onto your lawn.
The Difference in Granular and Liquid Fertilizers
In terms of lawn care, plants need three basic nutrients for growth, root development, enhancing green, and strengthening. Those nutrients are nitrogen, phosphorus, and potassium. Both liquid lawn fertilizer and granular fertilizer contain these three main nutrients, and while a plant can’t tell the source of the nutrient, it could be sensitive to the rate and delivery method.
Most liquid lawn fertilizer delivers a quick release of nutrients, while granular fertilizer has a slow release for your plants. When comparing liquid lawn fertilizer to granular fertilizer, we can look at the difference in the distance from the fertilizer nutrients to the plant roots for absorption to take place. Phosphorus is not a very mobile nutrient, and it has a hard time moving from where the fertilizer was applied to the root of the plants. Liquid lawn fertilizers provide a better option for your grass, with nutrients quickly applied to the soil or directly to the leaves, resulting in easier plant absorption. Applying liquids directly to the leaf blades will allow for a more rapid response.
Most granular fertilizers are meant to be slow-release fertilizers. Granular fertilizers usually contain higher concentrations since the nutrients need to last longer. This high concentration also means granular fertilizer can have a higher salt content compared to liquid lawn fertilizer.
Choosing the Right Liquid Fertilizer for Grass
To choose the right fertilizer for your grass, consider the following:
Soil Test Results: Examine your soil test results before choosing a liquid fertilizer. If you’re soil is low on a particular nutrient, you generally will want to apply that missing nutrient.
Consider Grass Type: Some grass types need more nitrogen than others. For example, Bermudagrass has some of the highest nitrogen requirements..
Consider your Soil Type: Sandy soils have low nutrient retention and may need more frequent applications of Nitrogen and Potash fertilizers. Clay soils generally retain nutrients are a higher level, as long as the soil is not compacted. Grass living within or on compacted clay soil will struggle to absorb nutrients, no matter how much you apply. Aeration will help unlock Phosphorus and Potassium reserves. Rich, organic soils are generally fertile and will need less Nitrogen fertilizer.
Growing Season: The season and the stage of grass development play a huge role in how much and what type of fertilizer should be applied. Lawn nutrient needs change as the grass grows and as the weather shifts. In the spring and fall, cool-season grasses will need more Nitrogen fertilizer to support leaf growth during the peak growing season. In late spring and summer, warm-season grasses will also need more nitrogen for grass growth. Before times of dormancy (summer and winter for cool-season/ winter for warm-season) a Potash fertilizer is needed.
