There is much in the action of lime in the soil that is not known, but all that we really need to know is simple and easily comprehended. The purpose of this little book is to set down the things that we need to know in order that we may make and keep our land friendly to plant life so far as lime is necessarily concerned with such an undertaking.
Leaching. One cause that appears obvious and easy of acceptance is leaching. In the case of one Pennsylvania farm, lying in a limestone valley, the lime had been washed out by action of water so freely that caverns formed under the surface, and a test showed a marked deficiency in the top soil. This land ceased to grow clover, and plantain and sorrel abounded. This case, which is not an isolated one, showed an unusually rapid loss, but we always expect to find the water from wells and springs in a limestone country strongly impregnated with lime. Drainage waters contain it. The draft by action of water is continuous, and in some types could easily account for sufficient loss to change the nature of the soil. We may place undue emphasis upon this factor, as other causes are at work, but leaching is a leading source of loss.
Chemical Compounds. A serious cause of lime exhaustion that is being studied by soil chemists is the presence of compounds in the soil that combine