Extensive investigations have been conducted to determine the influence of lime on acid soils, but there is still much to be learned regarding the reactions involved and the effects of additions of various kinds and amounts of lime on different soils. Soils vary widely in physical, chemical and bacteriological properties, and hence lime rarely has the same effect on different types. It has been noted that soils with practically the same hydrogen ion concentration may require different amounts of lime to neutralize the acidity. The organic matter and colloidal content are quite variable and will affect not only the need of soils for lime but also the reactions which occur as a result of the treatment.