This is the time of year many of us are probably thinking about fertilizing our lawn. The only way to see what your lawn requires is to pull a soil sample and let the Extension office send it off for analysis. Otherwise you are just guessing.

There are two types of spreaders for seed and fertilizer. The first type is a drop spreader. This type of spreader just drops the product the width of the spreader, which is good around areas that you do no need to add grass seed or fertilizer, like flower beds or driveways.

The second type of spreader is a rotary spreader. This type is good for large areas because it slings the product out in a circular pattern and allows you to cover much more area at one time.

Though the fertilizer manufacture has settings to use for the most popular spreaders, these are approximations at best. So the best thing that you can do is to calibrate your spreader to make sure you are putting out the right amount of product on your yard.

For a drop spreader, make a box out of cardboard to fit under the spreader and catch the fertilizer as it comes out. Set the spreader to the manufacturer's suggested setting, add spreader width by the distance that give you 100. Weigh the fertilizer that you catch and multiply by 10.

This will be the amount of fertilizer spread over 1,000 square feet. Adjust the setting until you get the right amount of fertilizer caught in your box. Your soil test report will tell you the amount of fertilizer to add per 1,000 square feet.

A broadcast spreader is more difficult to calibrate since you cannot catch the fertilizer that it throws out. To calibrate, first weigh out an amount of fertilizer to cover 100 square feet. Mark a starting point, then push the spreader several feet to measure the width over which the fertilizer is spread.

Now calculate and mark off 100 square feet and finish spreading the fertilizer over the area. Increase the setting number if there is still some material in the hopper, or decrease the setting if you run out before the end. Move across the yard so you do not over apply the fertilizer in one place.

With both methods, remember to record the setting so you will not have to do the calibration again next year. Also make sure not to calibrate in the driveway. This will keep fertilizer running into the streets and in the streams.

Michael Wheeler is coordinator for the Hall County Cooperative Extension Office. His column appears Fridays and at gainesvilletimes.com/life.