208 SOILS AND FERTILIZERS 



time when it is most needed. There should be some 

 plant food in the soil in a highly available condition 

 for the use of young plants, after that stored up in the 

 seed has been exhausted. Before commercial fertilizers 

 are used, careful field trials should be made. 



281. Experimental Plots. A piece of land well 

 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 lofeet 8 inches, 

 area 2176 square feet. Between each plot a strip 3 

 feet wide is left. The plan is to apply one element 

 or a combination of elements to a plot and compare 

 the results with other plots treated differently. 70 



282. 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 

 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. 



