Year 



Fig. 3. Acidity of timothy plots as affected by plowing and by two and 

 four-ton applications of ground limestone per acre, 1925-31 



28 29 



YEAR 



Fig. 4. Upper section of graph illustrates lessened acidity due to top- 

 dressing with nitrate of soda. Lower part shotvs that manure decreased 



acidity on unlitned plots 



