Choosing Between Drop
and Broadcast Spreaders There are two common types of lawn spreader:
drop or broadcast. The drop spreader is a familiar sight at garden
centers and hardware stores. If you are a homeowner with less than 5,000
sq.ft. of lawn area, an inexpensive drop spreader may be all you need.
Drop spreaders tend to be more manueverable in tight, awkward spaces and
are relatively easy to use.
Broadcast spreaders
throw the material out in a wider swath, sometimes as wide
as 8'. If you have a large area to cover, they can make
short work of it. They are, however, a little trickier to use, since you need to
keep up a steady walking
speed (usually 3 mph) and you need to be moving
when you activate the spreader. It's also harder to get a clean edge, although
some broadcast spreaders come with side deflectors, which let you get close
to sidewalks, beds and driveways without spreading
material on these adjacent areas. There are also small, handheld broadcast spreaders
suitable for smaller areas.
Calibrating Your
Spreader
It is always a good idea
to calibrate your own spreader, even if the manufacturer provides guidelines for
setting the spreader with different products. It's easy to calibrate
and, if you make a note of your results, you only have to do it
once for each product. Here's an example:
StepbyStep
Procedure 
Example 

We want to apply fertilizer at a rate
of 20 lbs per 1,000 sq.ft. The fertilizer comes in a 50 lb
bag. 
Take a sheet of plastic or a tarp
(ideally something bigger than 10' x 10' but smaller will work
too) and lay it on the ground. If it's breezy, put something
heavy on each corner to keep it in place. 

If your surface is big enough,
measure and mark an area of 10' x 10' on the
surface. An area of 10' x 10' ideal because it makes the
math easy, but it could be any dimension that gives you a convenient
square footage number  5' x 10' or 5' x 8', whatever you care to
make it. 
In our example, our area is 10' x 10'
or 100 square feet 
Set your spreader to the setting you
think will give you approximately the application rate you want. If
the material you want to spread is coarse and granular (for example,
corn gluten meal), set the spreader as wide open as it will go.
Don't worry about getting it right because you can adjust later.

Our fertilizer is fairly coarse,
granular material so we open it up about 3/4 of the
way. 
Empty a small amount of fertilizer or
other material into the spreader and run it over the area you marked
off as if you were making an application to your lawn.

We pour about 10 lbs of fertilizer
into the spreader. 
Carefully gather up the material you
spread on the surface. 

Take a container of some kind (you'll
use it to weigh the fertilizer you just spread) and weigh
it and using a household scale. 
Our bowl weighs 8 oz. 
Pour the material you spread into the
container and weigh it again. 
Bowl plus fertilizer weighs 32 oz
(or 2 lbs) 
Subtract the weight of the container.

Total weight (32 oz) minus weight
of bowl (8 oz) = 24 oz (or 1.5 lbs). 
Calculate the conversion factor for
1,000 square feet. (1,000 square feet divided by the square footage
of your test area). 
1,000 square feet divided by 100
square feet (size of our test area) = 10. Our conversion factor
is 10. 
Calculate the application rate of your
spreader for the current setting, using this material. Multiply
weight of applied fertilizer by conversion factor. 
Weight of fertilizer (1.5 lbs)
multiplied by conversion factor (10) = 15 lbs per 1,000
sq.ft. 
Adjust the spreader setting according
to your results. 
In our example, we want an application
rate of 20 lbs per 1,000 sq. ft., so we have two options.
We can either open up the spreader a
bit more to get the target application rate or we can close the
spreader a little and plan on making two passes with the spreader at
half the recommended rate. 
Write down the results so that next
time you'll know exactly what setting to use for this particular
product. 

Using Your
Spreader
Follow the
specific spreading instructions that come with your spreader. When working with spreaders, always load
a spreader on a surface where an accidental spill can be cleaned up
and won't matter (driveway, walkway, etc).
Common practice is to first run the
spreader around the periphery of the area you are treating; this ensures a
consistent application around the edge of your lawn. Next, you run the
spreader back and forth within the area bounded by your first perimeter
run. Always allow on overlap to avoid missed streaks or "holidays".
Ideally, apply your material at half the recommended rate and make two
sets of runs, first back and forth in one direction, then again another
set of runs at 90 degrees to the first set. This ensures a good consistent
coverage and it compensates for any uneven patches.
CleanUp and
Maintenance
The professionals
usually say that, after using a spreader, a thorough dry cleaning
beats a sloppy wet cleaning any day. It's certainly
a good idea to empty your spreader completely and shake out or
remove with a brush any remaining material. Keeping moving parts lubricated helps
too. 