Yields compared with the check plot are all positive ; and although the 

 differences fail to be significant, they support previous statements as to 

 residual fertilizer effects on Jackson farm. It seems fairly certain, there- 

 fore, that the effect of lime and residual fertilizer are carried into the oat 

 crop ; and although the differences are not large and fail of significance be- 

 cause of variations among plots of the same series, the effect is none the 

 less present. 



In Table XVII, two series appear which have not previously been 

 discussed because of conflicting data in potato yields. These are plots fer- 

 tilized with a 4-8-7 fertilizer, the phosphoric acid of which came from basic 

 slag, and one which had added magnesium. 



Slag gave a very slight increase in potato yields, while magnesium over 

 the years has not shown consistent stimulating eft'ects. While magnesium 

 hunger has been noted on the plots treated with concentrated materials, as 

 previously discussed, and on other farms within the area, this element does 

 not seem to be a limiting factor on land that has been manured heavily 

 during past years. Farms in the Colebrook area on which no manure is 

 applied in the rotation do exhibit magnesium hunger. Farm manures used 

 on this land prior to our lease may account for the failure of magnesium 

 to increase yields. 



Yields of hay during the second period are shown in the summaries 

 which follow. 



TABLE XVIII. Summary of Jackson farm hay yields in pounds per acre. 



Treatment 



Yield per acre 



P. E. 



Difif. from check 



P. E. 



'Neutralized with aluminum sulphate and sulphur. 



