8 STORRS AGRICULTURAL EXPERIMENT STATION. 
phosphoric acid, but neither has been much increased by 
potash. Potatoes have been benefited by all three ingredients, 
and especially helped by potash. 
Special nitrogen experiments.—Nitrogen in fertilizers may 
be of advantage in two ways: it may increase the total yield 
of the crop, and it may also increase the proportion of nitroge- 
nous compounds, 7. e., protein, in the crop. This latter effect 
of nitrogenous fertilizers has been but little understood in the 
past; the so-called ‘‘special nitrogen ’’ experiments carried on 
by the Station are helping to bring it out more clearly. The 
object of these experiments is to study the effects of the nitro- 
gen of different fertilizers upon the yield, and especially the 
composition of the crop. In making the experiments the crops 
are grown on a series of parallel plots, some of which are sup- 
plied with definite quantities of mineral fertilizers alone, while 
others have different quantities of nitrogen in addition to the 
minerals. The effect of the nitrogenous fertilizers upon the 
total yield of the crop is estimated by comparing the yields 
from the plots having the mineral fertilizers alone with the 
yields from the plots having the nitrogenous fertilizers in 
addition to the minerals. The effect of the nitrogen of the 
fertilizers upon the composition of the crop, and especially 
upon the proportion and amount of protein, is estimated in 
like manner by sampling and analyzing the crops from the 
different plots. “These experiments are carried out with corn, 
cow peas, and soy beans. They indicate that with the cereals 
the effect of the nitrogenous fertilizers is to increase not only 
the total yield of the crop, but also the proportion of protein, 
and thus, in a two-fold way, to increase their feeding value. 
With the legumes, on the other hand, the nitrogenous fertil- 
izers have very little effect upon either the amount or the 
composition of the crop. 
Experiments for the study of the effects of nitrogenous fer- 
tilizers upon the proportions of nitrogen in different species of 
plants have been made on a small scale in such a way that 
moisture and other external influences might be more com- 
pletely under control. In these experiments the plants are 
grown in pots by the use of the same kinds of nitrogenous and 
other fertilizers as are used in the plot experiments mentioned 
above, the total produce being weighed and taken for analysis. 
