FIELD EXPERIMENTS WITH FERTILIZERS. * 935 
years have been given.* The present account of the experi- 
ments of 1900 is designed as a brief report of progress. The 
experiments of the first and second classes mentioned above 
are described in the present article, and those of the fourth class 
in the article succeeding this. Those of the third class will 
probably be given in a future Report. 
SPECIAL NITROGEN EXPERIMENTS. 
The special nitrogen experiments on corn, cow peas and soy 
beans conducted by the Station in preceding years were con- 
tinued during 1900. The purpose of these experiments is to 
study the effect of nitrogenous fertilizers upon the yields and 
composition of the crops. The plan of the experiments has 
been described in detail in former reports.+ It consists, briefly, 
in growing the crops on a series of plots treated with mineral 
fertilizers supplying phosphoric acid and potash in definite 
amounts, and nitrogenous fertilizers supplying nitrogen in dif- 
ferent amounts, and comparing the weights and analyses of 
the crops from the different plots. The diagram on the next 
page and the discussion following it illustrate the methods of 
the experiment. 
The field used for the experiments is divided into ten long, 
narrow, parallel plots. These are indicated by the numbers 
oO, 7, 8, etc., at the north and south ends of the plots. The 
plots numbered o and oo receive no fertilizer. Plots 6a and 
66 receive dissolved bone-black at the rate of 320 pounds, with 
53 pounds of phosphoric acid per acre, and muriate of potash 
at the rate of 160 pounds, with 82 pounds of potash per acre, 
this mixture being called for convenience ‘‘mixed minerals.’’ 
Plots 7, 8 and 9 receive in addition to the minerals respectively 
160, 320 and 480 pounds of nitrate of soda, with 25, 50 and 75 
pounds of nitrogen per acre, while plots 10, 11 and 12 receive 
in addition to the mixed minerals respectively 160, 320 and 
A480 pounds of sulphate of ammonia, with 25, 50 and 75 pounds 
of nitrogen per acre. ‘The adjoining plots are separated from 
each other by narrow strips that are not fertilized. 

* See especially Reports for 1898 and 1899. + ldem. 
