Examples
Example1
Consider our 15' diameter tree that had an area of 176.71 square feet, but now let's say it's in medium soil and with a 60% wetting requirement for its area.
The Factors
Area of Plant = 176.71 sq. ft.
% to be wetted (as a decimal = .60
Minimum wetted area medium soil= 21 sq. ft. from table
The Formula
176.71 x .60 = # Of emitters
21
reduced to:
106 = 5 emitters
21
Example 2
The shrub area that has 3' x 3' spacing 60% wetted area desired Coarse sandy soil
The Factors
Plant area = 9 sq. ft.
60% wetted area desired = .60
Minimum sandy soil wetted pattern = 5 sq. ft. from the table
The Formula
9 x .6 = 1.08 or one emitter
5
If our answer had been significantly larger than the whole number we would have rounded up to the next number (i.e. 1.4 would be 2 emitters).
Try the two practical exercises on the following pages to help familiarize yourself with the emitters per plant formula.
Practical Exercise
Number of Emitters per Plant
Example 1
Tree roses singly spaced with 2.5 foot canopy diameters in medium (loam) grade soil. 100% of root area to be wetted.
The Factors
Plant area = _____________sq. ft.
% to be wetted (as a decimal)= __________
Minimum area wetted medium soil=___________sq. ft. from table
The Formula
X = emitters
Rounding up to the next whole number of emitters, how many will you use per plant?
____________emitter (s).
Example 2
An orange tree with a 25 foot diameter across its drip line in clay-like fine soil with 60% wetting required for plant area.
The Factors
Plant area=_________sq. ft.
% to be wetted (decimal)=__________
Minimum area wetted/emitter fine soil =_________________ sq. ft.from table
The Formula
X = emitters
Rounding up to the next whole number of emitters, how many will you use per plant?
____________emitter (s).
Answers to Excercises
Example 1
The Factors
Plant area = 4.9
of area to be wetted (decimal) = 1.0
Minimum area wetted medium soil = 21 sq. ft. from table
The Formula
4.9 x 1.0 = .23 emitters
21
Rounding up to the next whole number of emitters, how many will you use per plant? one
emitter (s).
Example 2
The Factors
Plant Area = 490.875 sq. ft.
% to be wetted (decimal) =.60
Minimum area wetted/emitter for fine soil =65 sq. ft. from table
The Formula
490.87 x .6 = 4.5 emitters
65
Rounding up to the next whole number of emitters, how many would you specify per tree? 5 emitters.
