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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. Determinethe area of each of those pieces.
Large rectangle:
67' X 130' = 8,710 ft2
From the formula: Area of a square/rectangle = Length XWidth
Triangle:
| 130' | 45' | 87' | ||||||
| -85' | -25' | -67' | ||||||
| 45' | 20' | = Leg 1 | 20' | = Leg 2 |
Leg 1 runs parallel to the 130' line and Leg 2 runsperpendicular 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 XWidth
B.) Add the pieces together.
| 8,710 ft2 | |
| +200 ft2 | |
| +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 byLawn
A.) Measure the area (Length X Width) of all spaces notcovered 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 WithFertilizer
Subtract the area of the property from the area not to becovered by lawn:
|
Property Area |
= |
9,410.0 ft2 | ||
|
Area Not Covered by Lawn |
= |
-4,857.5 ft2 | ||
| 4,552.5 ft2 |
= |
4,550 ft2 |
Therefore, there are 4,550 square feet of lawn tofertilize.
The University of Maryland recommendation for a lawnfertilizer application is one pound of NITROGEN per 1,000 squarefeet per application. This means that only one pound of actualnitrogen should be applied during any one application. Most coolseason grasses only need two pounds of Nitrogen per year. Mostlawns are not exactly 1,000 square feet. Since allUniversity of Maryland recommendations are based on per 1,000square feet, a conversion factor is needed. This conversion factoris already built into the formula below.
Step 4: Calculate the Amount of FertilizerNeeded
In reality, the question is: How much fertilizer is neededto maintain this lawn? In relation to the University'srecommendations, the question should be: How much Nitrogen isneeded to maintain this lawn? Technically, the question shouldbe: How much fertilizer is needed to add one pound ofactual 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 oneapplication to the 4,550 ft2 lawn.
For more information, contact Wanda MacLachlan
Last updated: 04/29/2009