2l8 SOILS AND FERTILIZERS 



tilled and of uniform texture, should be used for field 

 trials with fertilizers. After preparation for the crop, 

 small plots, 1/20 of an acre, are staked off. A con- 

 venient size is, length 204 feet, width 10 feet 8 inches, 

 area 2176 square feet. Between each plot a strip 3 

 feet wide should be left. In these experiments the 

 plan is to apply one element or a combination of 

 elements to a plot and compare the results with other 

 plots treated differently. 69 



279. Preliminary Trials. It is best to make pre- 

 liminary trials one year and verify the conclusions the 

 next. In making the tests the first year eight plots 

 are necessary and fertilizers are applied in the follow- 

 ing way : 



The first plot receives no fertilizer and is used as the 

 basis for comparison. 



The second plot receives a dressing of 8 pounds of 

 nitrate of soda, 16 pounds acid phosphate, and 8 

 pounds sulphate or muriate of potash. 



The third plot receives nitrogen and phosphoric 

 acid. 



The fourth plot receives nitrogen and potash. 



The fifth plot receives nitrogen. 



The sixth plot receives phosphoric acid and potash. 



The seventh plot receives potash. 



The eighth plot receives phosphoric acid. 



