
FIELD EXPERIMENTS WITH FERTILIZERS. 169 
be given ina later Report with those of future experiments. 
The experiment on soil improvement was begun during the 
past year, and is to be continued for several years. An account 
of the nature and plan of this work and the results of the pre- 
liminary experiment are given in the article following this one. 
SPECIAL NITROGEN EXPERIMENTS. 
The special nitrogen experiments of the past three years are 
an extension of a series which was begun in 1895 and con- 
tinued in 1896, as described in the Reports of the Station for 
those years. The crops with which the experiments are made 
are corn, cow peas, and soy beans. ‘These are grown on plots 
treated with fertilizers supplying nitrogen, phosphoric acid, and 
potash in different amounts and combinations, in the manner 
described in a later paragraph, the special purpose of the 
experiments being to study the effects of the nitrogen in the 
fertilizer upon the yields and the composition of the crops. 
The special nitrogen experiments with these crops are car- 
tied out on a series of plots which, prior to 1895, had been used 
for similar experiments with mixed grasses. For the earlier 
experiments with grasses the experimental field was divided into 
ten long, narrow plots, each one-eighth acre in size. These were 
numbered and fertilized as shown in the diagram on page 170. 
From this diagram it will be seen that two plots, Nos. o and 
oo, receive no fertilizer, while each of the other plots receives 
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. For con- 
venience this mixture of superphosphate and potash salt is 
called ‘‘ mixed minerals.”’ Plots 7, 8, and 9 received, in addi- 
tion to the mixed minerals, respectively 160, 320, and 480 
pounds of nitrate of soda, with 25, 50, and 75 pounds of nitro- 
gen, per acre, and are called the nitrate of soda group; while 
plots 10, 11, and 12 received, in addition to the mixed minerals, 
respectively 160, 320, and 480 pounds of sulphate of ammonia, 
with 25, 50, and 75 pounds of nitrogen, per acre, and are called 
the sulphate of ammonia group. ‘The adjoining plots are sep- 
arated from each other by narrow strips that are not fertilized. 
