Some Observations on the Relations of Acidity Tests and Soil Types

Interest in soil acidity probably arose from agricultural necessity and the term apparently reflects a belief that low productivity which may be corrected "cy liming implies acidity of the soil. Chemical studies have shown so-called acidity by many tests even in soils which need no lime to grow good legume crops. Soil survey studies havt> covered part of $.he gap between laboratory research and practical agriculture, without, to my knowledge, ever using soil acidity as the basis of separation of two types in the classification. soils are mapped according to their visible physical features rather than invisible, little known chemical factors, r/e have, however, generally recognized the acidic or basic nature of parent materials; have recorded whether land was considered "sweet" or "sour" and have gained some ideas from laboratory tests of samples which were usually taken after a county was mapped. Benefits of these studies have been lessened by the mistake of supposing that the reaction of a soil should correspond to that of its parent material, and also because soil samples have too frequently mixed soil materials having very different reactions;.