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Example of How to Determine Amount of Fertilizer Needed to Fertilize a Lawn
Bay-Wise Landscape Management
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Step 1: Calculate the Area of the Property
This is what a typical home landscape basemap may look like:
A.) Break the property into easily measurable pieces. Determine the area of each of those pieces.
Large rectangle:
67' X 130' = 8,710 ft2
From the formula: Area of a square/rectangle = Length X Width
Triangle:
| 130' | Â 45' | Â 87' | ||||||
| -85' | -25' | -67' | ||||||
| Â 45' | Â 20' | = Leg 1 | Â 20' | = Leg 2 |
Leg 1 runs parallel to the 130' line and Leg 2 runs perpendicular to Leg 1
1/2 (20' X 20') = 1/2 (400') = 200 ft2
From the formula: Area of a triangle = 1/2 Base X Height
Small "Square":
20' X 25' = 500 ft2
From the formula: Area of a square/rectangle = Length X Width
B.) Add the pieces together.
| Â 8,710 ft2 | |
| Â +200 ft2 | |
| Â +500 ft2 | |
| 9,410 ft2 | This is the total area of the property. |
However, a typical landscape may actually look like this:
Step 2: Calculate the Area of All Areas Not Covered by Lawn
A.) Measure the area (Length X Width) of all spaces not covered by lawn:
See column one and two of table.
B.) Add those totals together
See column three of table.
Step 3: Figure the Area of Lawn to be Covered With Fertilizer
Subtract the area of the property from the area not to be covered by lawn:
|
Property Area |
= |
9,410.0 ft2 | ||
|
Area Not Covered by Lawn |
= |
-4,857.5 ft2 | ||
| Â 4,552.5 ft2 |
= |
4,550 ft2 |
Therefore, there are 4,550 square feet of lawn to fertilize.
The University of Maryland recommendation for a lawn fertilizer application is one pound of NITROGEN per 1,000 square feet per application. This means that only one pound of actual nitrogen should be applied during any one application. Most cool season grasses only need two pounds of Nitrogen per year. Most lawns are not exactly 1,000 square feet. Since all University of Maryland recommendations are based on per 1,000 square feet, a conversion factor is needed. This conversion factor is already built into the formula below.
Step 4: Calculate the Amount of Fertilizer Needed
In reality, the question is: How much fertilizer is needed to maintain this lawn? In relation to the University's recommendations, the question should be: How much Nitrogen is needed to maintain this lawn? Technically, the question should be: How much fertilizer is needed to add one pound of actual Nitrogen to the lawn?
| Lawn size |
= |
4,550 ft2 |
| Fertilizer Formulation |
= |
24-2-12 |
| Application rate |
= |
1 pound of actual Nitrogen per 1000 ft2 |
From the formula:
| Total Fertilizer Needed = | N application rate in lb/1000 ft2 |
X |
Lawn size in ft2 |
| N content of fertilizer as a decimal | 1,000 |
Solve:
|
1 |
X |
4,550 |
= |
4.55 |
= |
18.96 lb of 24-2-12 |
|
.24 |
1,000 |
.24 |
So, 19 pounds of 24-2-12 fertilizer is needed to make one application to the 4,550 ft2 lawn.
For more information, contact Wanda MacLachlan
Last updated: 05/11/2006