EFFECT OF NITROGENOUS FERTILIZERS. 155 
SUMMARY OF EXPERIMENTS AND RESULTS. 
Summary. — The experiments on the effects of nitrogenous 
fertilizers were undertaken for the study of two problems: 
first, the relative economy of the use of nitrogen in different 
amounts and combinations in the production of grasses, grains, 
and legumes ; and second, the effect of the nitrogen of the fer- 
tilizer on the proportion of nitrogen compounds (protein) in 
the crop. These experiments have been made on the Station 
farm, and on a large number of farms throughout the State. 
The experiments were of two kinds, called “ special nitro- 
gen” and “soil test”” experiments. The number of soil test 
experiments in which chemical analyses of samples were made 
was quite limited, but the results have been incorporated with 
those from the special nitrogen experiments whenever it was 
thought that they would add to the general value of the work. 
The experiments here reported consisted, first, of special 
nitrogen field experiments upon mixed grasses, corn, oats, cow 
peas, and soy beans; and second, of a modified form of the 
same class of experiments, conducted on small plots with dis- 
tinct species of grasses; and third, of a small number of soil 
test experiments with corn and oats. 
The special nitrogen field experiments were conducted 
upon a series of plots, all of which, except two without any fer- 
tilizer, were treated with uniform quantities of mineral fertilizer 
(phosphoric acid and potash). In addition to the mineral fer- 
 tilizer different materials supplying nitrogen were used in vary- 
ing amounts, sufficient to furnish 25, 50, and 75 pounds of 
nitrogen per acre. The materials in which nitrogen was sup- 
plied were nitrate of soda and sulphate of ammonia, and in a 
few cases dried blood. The plots were generally from one- 
tenth to one-twentieth acre each. All in a given experiment 
were of the same size. 
The experiments on distinct species of grasses were con- 
ducted, in most cases, upon plots one-eightieth of an acre in 
size, and were similar to the special nitrogen field experiments 
except that lack of space prevented the use of so many plots. - 
The plots used were those receiving no fertilizer, those receiv- 
ing mineral fertilizers only, and those receiving mineral fer- 
tilizers plus nitrogen at the rate of 25 and 75 pounds per acre. 
The soil test experiments were undertaken primarily to 
study the fertilizer requirements of different soils and crops. 
They were generally laid out on a series of plots of from one- 
