Understanding Bermuda’s Nitrogen Requirements

Fertilizing your Bermuda grass lawn is a balancing act that requires a nuanced understanding of nutrient requirements, particularly nitrogen. While Bermuda grass is known for its love of nitrogen, too much of a good thing can lead to problems like rapid growth and thatch buildup. In this comprehensive guide, we’ll explore how to determine the right amount of nitrogen for your lawn, how to read fertilizer labels, and what types of nitrogen are available.

Nitrogen Requirements: How Much is Enough?

For Thin Lawns

If your Bermuda grass lawn is thin and needs filling in, aim for 1.0-1.5 lbs of Nitrogen per thousand square feet of lawn per month. This will encourage faster growth and help your lawn become denser.

For Mature Lawns

For lawns that are already mature and reasonably thick, a lower amount of 0.5 lbs of Nitrogen per thousand square feet per month should suffice. This will maintain your lawn without causing excessive growth.

Understanding NPK Ratios

While nitrogen is crucial, it’s not the only nutrient your lawn needs. Phosphorus (P) and Potassium (K) are also essential but are best determined through a soil sample test from your local extension office. As a rule of thumb, a 2:1 Nitrogen to Potassium ratio is generally safe, as Potassium tends to leach from the soil regularly. Phosphorus is rarely needed.

Reading Fertilizer Labels

The values of N-P-K are the percentage, by weight, of each of the 3 macronutrients in fertilizer: nitrogen, phosphorus and potassium. Let’s consider a Scotts Turf Builder with a 32-0-4 analysis. Here’s how to interpret it:

  • 32% Nitrogen: To get 1 lb of Nitrogen on your lawn, you would need to apply about 3 lbs of this product per thousand square feet.
  • 0% Phosphorus: This product contains no phosphorus which is great as too much phosphorus causes problems. However, not great if your soil test says your lawn needs it.
  • 4% Potassium: This means 4% of the fertilizer is potassium. It’s a low amount but you don’t need much. To put down 0.5 pound of potassium per 1000 sqft, you’d have to put down 12.5 pounds of fertilizer because 12.5 pounds x 0.04 = 0.5 pounds. However, 12.5 pounds of fertilizer would include too much nitrogen.

Types of Nitrogen: Slow vs. Fast Release

Slow Release Nitrogen

Usually coated Urea, slow-release nitrogen provides a steady supply of nutrients over 4-8 weeks. This is ideal for sustained, even growth.

Fast Release Nitrogen

Commonly found as Urea (46-0-0) or Ammonium Sulfate (21-0-0), fast-release nitrogen is quickly used up by the grass or lost through volatilization or leaching within 2-3 weeks. It’s generally cheaper but needs to be applied more frequently. It is ideal for pushing growth, and particularly used by those who don’t mind more maintenance in exchange for better results.

Nitrogen Frequency

For fast-release nitrogen like urea or ammonium sulfate, one might apply every 2-3 weeks to maintain grass vigor without leaching or volatilization losses. For slow-release forms such as polymer-coated urea, monthly applications are sufficient. The path you choose is based on your goals.

Spoon Feeding and Liquid Fertilization Techniques

Spoon feeding involves applying small amounts of nitrogen weekly, keeping your lawn consistently green and growing without peaks and troughs in nutrient availability. For liquid fertilization, dissolve urea or ammonium sulfate in water and apply no more than 0.25-0.5 lbs of nitrogen per 1000 sq ft. Water the lawn immediately post-application to enhance nutrient uptake and prevent burn. The more nitrogen you use, the quicker you need to water in. The application limits for liquid fertilizer are lower than if applied in granular form. The results are quicker and uptake is better via this foliar application. Granular applications rely on correct pH and other properties of the soil for efficient uptake, whereas foliar bypasses any soil inefficiencies.

Example Fertilizer Schedules

As you increase your frequency, you decrease the amount of nitrogen you apply per application. Here are some example schedules you might follow throughout the growing season. The examples use urea and ammonium sulfate, choose one based on your needs. You don’t have to use them, but they’re popular.

Goal: Maintain lawn

Week NumberOption 1
Urea Amount (lbs per 1000 sq ft)
Option 2
Ammonium Sulfate Amount (lbs per 1000 sq ft)
Week 11.09 lbs2.38 lbs
Week 20 lbs0 lbs
Week 30 lbs0 lbs
Week 40 lbs0 lbs
Week 50 lbs0 lbs
Week 60 lbs0 lbs
Week 71.09 lbs2.38 lbs
Week 80 lbs0 lbs
Week 90 lbs0 lbs
Week 100 lbs0 lbs
Week 110 lbs0 lbs
Week 120 lbs0 lbs

Goal: Push growth via granular application

Week NumberOption 1
Urea Amount (lbs per 1000 sq ft)
Option 2
Ammonium Sulfate Amount (lbs per 1000 sq ft)
Week 11.08 lbs2.14 lbs
Week 20 lbs0 lbs
Week 31.08 lbs2.14 lbs
Week 40 lbs0 lbs

Goal: Push maximum growth via liquid application

Week NumberOption 1
Urea Amount (lbs per 1000 sq ft)
Option 2
Ammonium Sulfate Amount (lbs per 1000 sq ft)
Week 10.82 lbs1.79 lbs
Week 20.82 lbs1.79 lbs
Week 30.82 lbs1.79 lbs
Week 40.82 lbs1.79 lbs

Conclusion

Fertilizing your Bermuda grass lawn is not a one-size-fits-all endeavor. The amount of nitrogen you need depends on the current state of your lawn and your goals for its appearance and health. By understanding how to read fertilizer labels and the differences between slow and fast-release nitrogen, you can make informed decisions that will help your Bermuda grass thrive. So grab that fertilizer bag, do some quick math, and get ready to give your lawn the nutrients it craves.


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