Proper fertilization is one of the essential management tools for maintaining a beautiful, healthy lawn. When used properly, a high quality fertilizer can provide the nutrients needed to create the lush, green landscape you seek for the coming summer months.
There are 16 essential nutrients for proper plant health. Some are considered macronutrients (used in larger quantities by plants). Others are micronutrients (required in smaller amounts).
I will focus on the macronutrient that is normally needed in the greatest amounts – nitrogen.
Nitrogen has many functions in plants related to chlorophyll, amino acids, proteins, nucleic acids, and enzymes. It’s important for plant growth and maintains the healthy green color that everyone loves.
Unfortunately, nitrogen is not only used in large quantities, it is also mobile in soils. This means that it may be present in the root zone of the lawn one day and disappeared the next due to heavy rainfall or watering. It can leach down past your roots.
We see this more in sandy soils, but it can happen in clay soils like we have here in the San Angelo area. This can lead to a lack of nitrogen and a terrible yellowing effect throughout the lawn. In most cases, the yellowing begins on the older leaves and then moves to the center of the grass plant where the new leaves form.
Another problem that addresses rainfall or irrigation affects locations that do not drain well and whose soils remain excessively moist for extended periods of time. The oxygen in the soil profile is limited in these saturated soils, resulting in a loss of nitrogen known as denitrification.
Other forms of nitrogen loss are erosion and runoff problems.
When should you fertilize your lawn?
Don’t be surprised if your local kindergarten or county extension agent recommends fertilizer use this time of year. Experts recommend your first application about 30 days after the last death frost and the last fertilization about 30 days before the first death frost.
When making a decision, be aware that inorganic and organic sources can cause enormous environmental problems if used improperly. Nitrogen and phosphorus ending up on the streets and in storm sewers can lead to algal blooms and dead fish.
So please take the time to apply a good, even application with the correct fertilizer.
How do you choose the right fertilizer and determine how much to apply?
Taking a soil sample is a good first step. It provides useful information about the nutrient levels of your soil and can help you develop an environmentally conscious approach to nutrient management.
Note that the three numbers on the fertilizer bag represent NPK (Nitrogen-Phosphorus-Potassium) and these numbers are percentages. In other words, a 15-5-10 fertilizer would have 15 percent nitrogen, 5 percent phosphorus, and 10 percent potassium. So a 50 pound bag of this fertilizer would contain 7.5 pounds of nitrogen (50 pounds x 0.15), 2.5 pounds of phosphorus, and 5 pounds of potassium.
Apply fertilizer to your lawn in measured amounts. This means you need to know the surface area (in square feet) of your location and how much nutrient your particular lawn grass needs in a given application and in a given year.
Remember that not all lawn grasses require the same fertility (i.e. nitrogen). The type of lawn grass, the analysis of the soil sample, the desired quality and the use of the site will determine the number of fertilizations you will make in a given growing season.
For example, a Bermuda lawn may use 3 pounds to 5 pounds of nitrogen per 1,000 square feet per year. A Zoysia grass or St. Augustine lawn may only need 2 to 4 pounds of nitrogen per 1,000 square feet per year.
A more detailed explanation of lawn fertilization can be found at cosatx.us/parks. We have published an expansion publication on lawn fertilization.
The website also has lists, descriptions and maps of all the parks that you and your family can enjoy here in San Angelo.
Roger Havlak is the Senior Manager of Parks for the City of San Angelo. Contact him at 325-659-8563 or [email protected].
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