Clay soil can benefit greatly from aeration and nitrogen, but lime is only needed if the soil's pH level is low. Lime does not help clay soil in any other way. Adding compost (organic material) is also a benefit to clay soil, as is sand.

How much lime do I add to clay soil?

It takes 20 to 50 pounds (9-23 k.) of ground limestone per 1,000 square feet (93 m²) to correct a mildly acidic lawn. Strongly acidic or heavy clay soil may need as much as 100 pounds (46 k.).

Why does clay soil need more lime?

As soil acidity increases (the lower the pH), the more lime is needed to ameliorate acidity. More lime has to be added to clay soils and peaty soils than to sandy soils to achieve the same result because different soil types react in different ways to the application of lime.