Hello Steve,

Good luck with your quack grass control regimen.

We could not find a soil test for you. Was it an MSU soil test? Grass is pretty accommodating of a wide range of pH values. At the rate you will be applying the nitrogen, the sulfur will not present a problem in the lawn: https://turf.purdue.edu/sulfur-is-not-effective-for-lowering-ph-of-turfed-soils/

The physics of a spreader makes the amount of product delivered quite variable even in two devices from the same company, so calibration of your specific spreader is important. The following article from Penn State is very good at explaining how to calibrate a spreader: https://extension.psu.edu/calibrating-your-fertilizer-spreader

Unfortunately, the product you chose would not have been my suggestion for light applications of fertilizer for two reasons. (1) While the sulfur will help lower soil pH, I would generally decouple the two applications and address the fertility with a x-0-0 fertilizer and apply sulfur separately at the rate suggested by the results of your soil test. (2) 21-0-0 fertilizer is pretty concentrated. Light applications of nitrogen will require a very small amount of product spread over a large area.

21-0-0 product means that each pound of fertilizer will contain .21 pounds of nitrogen. If you want to apply 20% of normal application rates of nitrogen to your lawn, you will want to apply 0.20 x (1 lb of nitrogen) or 0.2 lbs of nitrogen. This means that you will need to apply 1 pound of the 21-0-0 product per 1000 sq feet. To apply that small an amount with your spreader may be difficult to control and obtain even application.

A product with lower nitrogen percent, means that more product needs to be applied to reach the same 0.2 pounds per 1000 sq feet. For example, a 5-0-0 fertilizer yields 0.05 pounds of nitrogen per pound of product. To obtain 0.20 pounds of nitrogen, you would need to spread 4 pounds of product. The larger amount to apply would be easier to control and be more repeatable.

But you have the product already so measure out 1 pound of fertilizer, mark out 1000 sq feet of lawn and choose a small setting on your spreader and see if you use all the product or not before you cover the 1000 sq feet. Reset the product to 1lb in the spreader, increase the spreader setting and do another 1000 sq feet. Keep doing this until you are applying 1 pound of product in a 1000 sq foot section. When you reach that application rate, you have the correct setting on your spreader.

In the future, I would purchase a regular lawn product and apply 0.2 pounds of nitrogen at a time per the setting on the label. Or you could buy and use a “just nitrogen” product – x-0-0.

I hope this helps.

Steve,

Unless you have, or have access to, a professional fertilizer spray apparatus, your application would have to be made by a hose end sprayer. You would need to dilute the concentrate in the hose end sprayer and evenly spray all the area you wish to treat. Applying an even concentration of fertilizer in this manner may be even more difficult than calibrating a spreader. I could not even begin to give you a recipe for liquid fertilizer. For that type of product, using a dilute amount is “off label” use and we cannot condone that.