1882.] EXPERIMENTS WITH FERTILIZERS. 347 



This duplicating the " mixed mineral " serves the three-fold purpose 

 of testing the uniformity of the soil, replacing unmanui'ed plots, 

 and showing more accurately the actual effects of the nitrogen. 



DIRECTIONS. 



Read carefully the explanations herewith, and the " Directions 

 for the Experiment," and "Condensed Directions," which go with 

 each set of fertilizers. The main points are to (1.) Select level 

 or nearly level and uniform land. (2.) Lay out the plots accurately 

 (see figures for calculating dimensions in " Condensed Directions "). 

 (3.) Distribute the fertilizers evenly over the plots. (4.) Conduct 

 the experiment carefully, and (5.) Make an accurate report, for 

 which blanks will be sent in due season. 



Please indicate the boundaries of the plot, by strong stakes, and, 

 if convenient, arrange to repeat the experiment with the same fertili- 

 zers on the savie p)lots through a series of years and crops. 



SIZE OF EXPERIMENTAL FIELD. "ONE ACRE " AND "TWO ACRE " 



EXPERIMENTS. 



Experience implies that, under ordinary circumstances, plots of 

 one-twentieth acre each, making one acre for the twenty plots, will 

 suffice. Where convenient, however, it would be well to use two 

 acres. This has been done to advantage when two crops, as corn 

 and potatoes, have been grown side by side on each plot for com- 

 parison, an excellent plan for testing the comparative feeding ca- 

 pacities of the plants. 



If practicable leave an unmanured strip, say three feet wide, 

 between each two plots, to prevent the roots of each from feeding 

 on fertilizers of the next. This will increase the whole area, but 

 will make the experiment much more valuable. 



KIND OF CROP. 



The kind of crop will, of course, be selected by the experimenter. 

 Experiments are needed upon all our ordinary crops, but especially 

 on wheat, barley, rye, oats, corn, sorghum, grass, clover, onions, 

 potatoes, roots, and in the South, sugar cane and cotton. 



