BULLETIN 278 

 SOIL TEST EXPERIMENT AT AROOSTOOK FARM 



SECOND REPORT 



Chas. D. Woods 

 SUMMARY 



This soil test experiment is conducted on Caribou loam 

 on Aroostook Farm. While the results are probably of more 

 or less general application to this type of soil they have no 

 bearing on the fertilizer needs of other types of soil. 



In this test available ammonia (nitrogen), available phos- 

 phoric acid, (phosphorus), and water soluble potash (potas- 

 sium) were used singly, in combination by twos and by threes, 

 in amounts varying from none to 240 pounds per acre. 



This is a long term experiment designed to extend over 

 many years. 



The crops used are potatoes, oats and clover in a 3 year 

 rotation. 



Each plot and series of plots are in triplicate. 



Two crops have been grown on each series of plots. 



The yields of clover have been too uneven to make con- 

 clusions possible. 



The oat stand in 1917 was very uneven. That of 1918 was 

 fairly uniform on each plot. 



The potatoes on each plot were quite uniform in both 1917 

 and 1918. 



While only tentative conclusions can be drawn ammonia 

 seems to be the limiting factor on this soil for oats, while 

 neither phosphoric acid nor potash have much effect upon the 

 yield of grain. Ammonia is also the limiting factor in potato 

 yields, small amounts of potash increase the yield and phos- 

 phoric acid has no effect. 



For Caribou loam on Aroostook Farm this soil test indi- 

 cates that: 



