142 MASS. EXPERIMENT STATION BULLETIN 212. 



In 1S97 and 1902 for potatoes, in 1898, 1899, 1900 and 1901 for onions, 

 and in 1903 and 1904 for grass and clover, the fertilizer applications were 

 doubled. In 1899 lime was applied to the west half of the field, and was 

 repeated in 1904, 1907 and 1916, a total of 4| tons per acre of lime in 

 one form or another being applied over a period of eighteen years. 



Table IV of the Appendix gives the record of yields over the period 

 of the experiment. 



Variation in Checks. 



The check plots were verj'' variable. The j'ields of grass and clover on 

 the limed and unlimed halves of the field illustrate this fact. 



Table 7. — Grass and Clover Yields on Check Plots (Yields per Acre, 



Pounds) . 



The highest yielding plots in each year are bold-faced type. 



Plot 1 on the limed and unlimed portions of the field is seemingly 

 superior, at least in its ability to grow grass and clover, to Plots 4 and 8. 

 Plot 12, unlimed, is the poorest of the checks, while on the limed portion 

 of the field it is superior to Plot 1. Owing to this variation in different 

 parts of the field, the data presented in Table IV of the Appendix do not 

 permit of clear-cut numerical discussion. They serve to indicate ten- 

 dencies rather than to furnish statistical proof. It is probable, also, that 

 the natural variation in the checks has been exaggerated somewhat by the 

 fact that there has been cross washing on this field, the soil working in a 

 more or less diagonal direction from the unlimed portion of Plot 12 to the 

 limed half of Plot 1. 



Effect of Lime and of Fertilizer Applications. 



Even though the uniformity of conditions is not as great as could be 

 desired, the results from the use of many of the plant food and lune com- 

 binations are so striking as to be beyond the range of probable experi- 

 mental error. Table 8 has accordingly been prepared, showing the com- 

 parisons for a number of the more important crops grown. From this 

 table the following facts are developed: — 



