346 
Journal of Agricultural Research 
Vol. XXVII, No. * 
Table I .—General plan of commercial fertilizer plats in 1915, 1916, and 1917 on Uni¬ 
versity Farm , St. Paul , Minn a 
Fertilizer. 
Fertilizer, kind and amount in pounds per acre. 
Kind. 
Amount 
per acre 
(pounds). 
Sodium nitrate. 
None. 
Potassium chlorid. 
1,000 
500 
250 
1,000 
500 
250 
2 , OOO 
1 
2 
3 
4 
5 
6 
7 
Acid phosphate. 
I, OOO 
8 
9 
10 
II 
12 
13 
14 
500 
15 
16 
U 
18 
*9 
20 
21 
None. 
22 
2 3 
24 
25 
26 
27 
28 
a The plats are numbered from left to right in all plat plans. 
It will be noted from Table I that there were 28 plats in the regular 
series. The fertilizers, and amounts applied, are indicated at the left 
of the horizontal columns and at the tops of the vertical ones. For 
instance, plat 3 (reading from the upper left-hand plat to the right), 
received an application of acid phosphate at the rate of 2,000 pounds 
per acre and sodium nitrate at the rate of 250 pounds per acre. Plat 
4 received only phosphate, and plat 25 is a control. Each of the three 
fertilizers was used alone in three concentrations, and combinations 
were made between acid phosphate and each of the other fertilizers. 
This plan was changed slightly in some of the experiments in order to 
make other combinations of fertilizers, and, on the poorer soils, a complete 
fertilizer also was used. In addition, experiments were made with 
barnyard manure in combination with other fertilizers. In 1915, plats 
were established at University Farm on cabbage, clover, and alfalfa 
soils. The details will be given under each experiment, as they vary 
considerably. 
The principal commercial fertilizers used in the tests made during the 
first four years were acid phosphate, sodium nitrate and potassium 
chlorid. In 1916, potassium chlorid could not be obtained, so potas¬ 
sium sulphate was used instead. The barnyard manure used was well 
rotted. 
The acid phosphate was worked thoroughly into the soil before seed¬ 
ing, while potassium chlorid and potassium sulphate were applied as a 
top dressing immediately after seeding. The sodium nitrate was applied 
as a top dressing shortly after the plants had emerged from the soil, 
and applications were made at two-week intervals, at the rate of 250 
pounds per acre, until the total amount had been applied to each plat. 
The manure, which always refers to well-rotted barnyard manure, was 
applied before seeding and was thoroughly worked into the soil. 
A resistant and a susceptible variety of wheat were sown in each 
plat in most of the experiments at University Farm. The varieties 
used and their average degree of resistance to stem rust under field 
conditions will be given under the description of each experiment. 
Under ordinary conditions a severe epidemic of stem rust is not sure 
to occur every year. Owing to location, no attempt was made to induce 
the development of artificial epidemics on the wheat in the plats on the 
Quinn farm, or at Anoka and the Crookston substation. Definite 
measures, however, were taken to produce a severe epidemic on the 
