Question
Stores in our area (Northeast Ohio) sell all 3 products and I have not been able to get any explanation from the people that work in the stores that satisfy my curiosity of when should I use one or the other - all I have gotten is that gypsum is better but noone can tell me why or why not limestone or lime.
My soil is all clay with about 1" of topsoil that I put on top. I am also surrounded by trees and lots of leaves which makes it acidic.
Thanks,
Bill

Answer
Northeast Ohio is just like the rest of the country when it comes to advice about these things.  People know the basics.  But there's more to it.  Not a lot more, just more.

Gypsum will loosen clay, yes.  But it's not your answer here.

Lime will lower the pH, yes.  Again, it's not your answer.

Limestone - depends, if it's pelletized lime, it will slowly alter the pH.  I prefer that to powdered Lime, which is a little cheaper and works faster but flies all over the place and does not help long term.

Your answer is right at the top of your question, next to the word Subject:  SOIL CONDITIONERS.

First, cogratulation yourself for getting a house with Clay Soil.  Because Clay is a wonderful thing to have in your garden.

Surprised?

I know, I know - people complain all the time about Clay.

It's hard to dig in.  It's slippery when wet.  It's so nonporous you can make soup bowls out of it.  And it's a lot of trouble to correct.

Besides, if it needs correcting, it must be a problem, right?

Truth is, that's all Urban Myth, my friend.

Clay is FILLED with vitamins and minerals!

The stuff is made of aluminosilicates (Al4Si4O10(OH)8).

And since Clay particles are NEGATIVELY charged, they are able to hold POSITIVELY charged ions.  And any soil that can do that is PACKED WITH NUTRIENTS.  Calcium, Magnesum, Potassium, and other plant nutrients are positively charged ions.

Scientists give this special quality a number.  It's called the Cation Exchange Capacity - the "CEC".  The MORE CLAY you have in your soil, the HIGHER your CEC.

Remember - The more Clay a soil has, the bigger the CEC will be.

Now that you know that, you can appreciate your clay.  It's a selling point when it's time to sell the house - tell the Realtor about the terrific CEC.

Sandy soil may be great for drainage.  But it's the BIGGEST LOSER when it comes to Cation Exchange Capacity.  It CAN'T hold nutrients.  Any fertilizer you put on grass you try to grow in sandy soil, well, it just washes right out as you
water it in.

So thank the Lord for your Clay.

Clay also binds soil particles and holds moisture in ways that Sandy soil can only dream of.  We won't go into that today.  Because we have other things to discuss.

First:  Your Clay needs Organic Matter.  That's not as easy as sprinkling your soil with gypsum.  The topsoil on top of it will shield it from anything you put over the two of those layers.  But tilling it in is not going to work, either, even if you did not care about destroying your lawn and starting from scratch.

You need to get Organic Matter down - Peat moss, Humus, Compost, AGED Manure in a ratio of 1:1.  These will correct the spaces between the molecules and fortify your Soil with Nitrogen.

Humus is especially critical here, Bill, because it injects microbes back into your soil, where they can complete the Nitrogen cycle and attract beneficial microbes, insects and earthworms.

Clay is not the biggest problem homeowners face when they try to grow grass in high Clay soil.

Nope.

The biggest problem is that the homeowners watch the TV commercials with happy families running around on grass treated with things called Weed and Feed, Turfbuilder, Grub B Gone, etc.  They think that RoundUp on the grass is just a responsible homeowner's way of taking care of their yard.

OK.  Maybe you prefer Waldbaums and Pathmark prices to the Whole Foods markups.  Maybe you simply think that organic gardening is for Granolaheads in California.

Tsk tsk, Bill.

Your grass CAN'T grow in purified soil.  

You NEED the balance of Nature - the Nitrogen cycle - the smooth, effortless, easy way that microbes and molecules work together to create a soft, healthy soil.  

So when you put grub killer (and why would you have grubs, anyway?  natural predators should be taking care of those) in the soil, you kill the microorganisms in your soil.  No more earthworms.  No more birds.  No more Nitrogen.  No tilth.  (You need tilth for healthy roots and healthy soil and moisture management.)

The soil is no longer healthy.

You don't have to buy lovebeads or weak moccasins.  You just have to do a few sensible, intelligent things, done by sensible, intelligent people all over the country.

Even if your yard is too shady to grow grass, Bill, you should still build up your soil.  It's good for Nature.

You'll know you're on the right track when all the birds flock to your lawn for breakfast.  You'll hear them in the morning.

For the acid, Pelletized Lime is best.  It takes a while to affect the soil so get started.  Put down a dose twice a year, since you have a tendency toward low-pH influences.  Unless you are growing Azaleas down there under the trees instead of grass.

There's a lot to digest here.  Sorry 'bout that.  If you need clarification, please let me know and I'll get into the Chemistry.  Hard to follow? Yes.  Will it work?  Absolutely.

Keep in touch.