Who would think that people would use dull tools for digging holes, cutting grass, branches, limbs or anything in the yard that needs cutting. But, I am here to say that I have seen it too many times to be astonished anymore. It just boggles the mind! The main use of, say a shovel, is to dig. To dig, means cutting small segments of dirt. If you "cut" the dirt with a sharp shovel, then you will do that task as fast as you can dig. But … If your shovel is dull, like I've seen a lot of people I know, then you're digging and using your weight to dig and dig and spending much of your time just spinning around and tiring yourself out.
If you have a project that requires cutting of any substance whether it be dirt, grass, branches of anything else, then sharpen the tools you are going to use for the task.
To sharpen your shovel, use a medium file and file about a 55-60 degree bevel on the top of the shovel. If you see any pits on the back side, then file them smooth at the same angle as the back of the shovel before filing on the front.
I sometimes use a rotary stone to grind my shovel instead of a file. Care must be taken to not grind too much material off the edge. Also, if you decide to use a grinder, take care to not let the cutting edge of the shovel get too hot while grinding. This can change the temperature of the metal and cause way more problems when you are digging.
One thing to remember. Dirt is the 800 pound gorilla when it comes to cutting. Dirt will dull any type of cutting tool faster than anything you can imagine. So if you have a need to cut through dirt, you should expect to be sharpening your tools more often than you would normally imagine.