Applying the right amount with a rotary broadcast spreader
Method 1
- Fill spreader with a weighed amount of fertilizer.
- Layout calibration area in length. 100', 50', 200', etc.
- Apply the fertilizer the length of the run.
- Measure the width of the spread.
- Weigh the remaining fertilizer in the spreader and subtract this amount from the amount you started with.
Now you have all the variables for calculation. Length, width, and amount of fertilizer used.
Calculation
Length x width = sq.ft. of area
Example 7' spread x 100' run = 700 sq.ft. of area If you applied 5 lbs. of fertilizer in this area, then you applied 5lbs./700 sq.ft. You can then use a ratio to find the rate/1,000 sq.ft. or rate/acre.
You spread 5 lbs./700 sq.ft.
5 lbs. :: X Cross multiply the ratio 700 x X = 5 x 1,000 or 700X = 5,000 700' 1,000' Then: X = 5,000 and X = 7.14 700
Thus: you applied a little more than 7 lbs. of fertilizer per 1000 sq.ft. If you were using Turf Supreme then the spreader setting would need to be closed to apply the recommended rate of 6.25lbs./1,000.
Method 2
- Fill spreader with fertilizer.
- Run spreader over a pre-marked area.
A) Area must be smaller than the spread pattern.
B) Use a small tarp to collect the applied fertilizer - Collect and weight the fertilizer that was applied to the tarp.
- The formula for the pounds of fertilizer that was applied is:
