This is important for two reasons. The solubility of the limestone increases as it is ground finer.
Limestone affects only a very small volume of soil around each particle.
Therefore, the finer limestone is ground, the more particles it has, and if there is adequate mixing, more of the soil will be in close contact with limestone and thus be neutralized. For example, in a situation where aglime is applied to neutralize the soil acidity to raise the pH to 7.0, material larger than 20 mesh was of little value for increasing soil pH and that only 100-mesh material came close to achieving that goal. Therefore, it would seem desirable to use only 100 mesh or smaller limestone. However, this decision must be balanced against the high cost of grinding limestone to finer than 100 mesh. A compromise must be reached so that the material is fine enough to be effective agronomically but still economically sound.