(1) The experiment as a whole showed that pH determinations may be made at any time throughout the year with assurance of being reliable as a relative indicator of lime requirement. (2) A comparison of the pH determinations made in 1928 with those made in 1930-31, show that the plats have become more acid. (3) The pH values of the soil paralleled the quantity of lime applied. Where no lime was applied the soil was found to be very acid, but increasing applications of lime brought the reaction gradually to the neutral point. (4) There appears to be a definite relation between pH and crop yield. For each crop the yields increased up to a certain pH; beyond which they decreased again. The optimum pH for the crops grown in the experiment reported here are as follows; Alsike clover 5.8 Red clover 6.3 Sweet clover 6.5 Soybeans 6.3 Wheat 6.2 Barley 6.2 Rye 5.9 Corn 6.3 Potatoes 5.4 / M.S.