12 



MASS. EXPERIMENT STATION BULLETIN 333 



Table 7. — Yields of Corn in 1922 and 1923 

 Pounds per Acre 



Plot 



Southwest 



Northwest 



Southeast 



Northeast 



Ears Stover Ears Stover Ears Stover Ears Stover 



1922 



5 Ammonia 9 



6 Ammonia 7 



7 None 79 



8 Ammonia 116 



9 None 106 



10 Dry fish 118 



1923 



5 66 



6 62 



7 73 



8 102 



9 69 



10 115 



PERIODICAL TREATMENT WITH LIME 



The soil reaction of each subplot was measured periodically and application 

 of limestone made in accordance with the results obtained. The values for 

 pH on Plots 7, 9, and 10 fluctuated from 6 to 7, but most of the time at inter- 

 mediate points between. Plot 8 with its sulfate of ammonia lost its reserve 

 of carbonate of lime more quickly and Plots 5 and 6 formerly treated with the 

 same fertilizer also showed similar exhaustion, manifested by the drop of pH 

 values to 5.4 as the low point. 



In 1927 the low pH values were found before corn was planted, and 1000 

 pounds per acre of ground limestone were applied to the west half of every 

 plot. Again in October, 1930, the low pH of 5.5 was observed on the same 

 three plots. The following spring, 1931, 2000 pounds per acre of ground lime- 

 stone were applied over all plots. Because alfalfa was to be seeded in 1933, 

 2000 pounds of limestone per acre were again applied throughout all plots. 

 In 1934, pH values ranged from 6.4 to 7.0 throughout the field. The west 

 half of Plot 5 was at the lower limit and Plot 9 at the higher limit on all sub- 

 plots. The nitrogen fertilizers applied in 1933 were calcium nitrate on Plot 5, 

 leunaphos on Plot 8, and calurea on Plot 10, equivalent to 45 pounds of ni- 

 trogen per acre for each chemical. A like application was made in 1935. 





NITROGEN AND ORGANIC MATTER IN SOIL AND SUBSOIL 



To supplement the evidence obtained by analyzing the crops for nitrogen, 

 the soil of every subplot was analyzed in 1924, 1927, 1931, and 1934. Each 

 sample was taken from the center and four corners of the square rod at the 

 center of the subplot. Conditions at these five points were considered to 

 change similarly to the average changes on the whole subplot in the intervals 

 between samples. 



