EFFECT OF NITROGENOUS FERTILIZERS. ata 
of the experiments, 

Size of plots. | No. of No. of plots. No. of 






experiments. analyses. 
20 sq. rods 3 25 46 
2 sq. rods 7 28 28 
2 sq. rods i 28 28 
2 sq. rods | 5 20 20 
64 sq. feet | I 2 2 
2 sq. rods 2 8 8 
64 sq. feet 2 4 4 
2 sq. rods 2 8 | 8 
2 sq. rods 2 8 8 
64 sq. feet I 2 2 
64 sq. feet I 2 2 
64 sq. feet I 2 ae 
64 sq. feet I 2 2 
8, 13%, 16, or 20 sq. rods 4 39 35 
8, 135, 16, or 20 sq. rods | 4 39 35 
3 2, 8, or 16 sq. rods 8 129. 117 
3.2, 8, or 16 sq, rods 8 129 hy 
13% Sq. rods I 12 12 
8 or 16 sq. rods 2 26 26 
8 or 16 sq. rods 2 26 26 
6.4 sq. rods 4 40 51 
6.4 sq. rods 4 40 33 
72 619 612 



straw, because the plants dropped their leaves to large extent 
before the seeds were fully matured. 
Soil Test Experiments — The experiments which have been 
called “soil tests’’ were undertaken primarily to learn the 
deficiencies of the soils in regard to the essential ingredients of 
plant food, especially the phosphoric acid, potash, or nitrogen 
needed to produce the given crop. The plan of the experi- 
ments for soil tests consists in applying, upon parallel plots of 
land, fertilizers containing nitrogen, phosphoric acid, and pot- 
ash. The quantities were generally such as to supply about 
25 pounds of nitrogen, 53 pounds of phosphoric acid (PO); 
and 82 pounds of potash (K,O) per acre. These ingredients 
were applied to different plots singly, in all combinations of 
two, and finally all three together. The arrangement of the 
