184 
Journal of Agricultural Research 
Vol. XXXI, No. 2 
The physical and chemical composition of this soil is quite uni¬ 
form to a depth of 10 feet. The soil is exceptionally rich in phos¬ 
phorus and potassium, but low in nitrogen and humus. The calcium 
and magnesium contents, mainly in the form of dolomite, are excep¬ 
tionally high. The soil is especially fertile when supplied with 
optimum moisture and organic matter. 
MANURE AND IRRIGATION 
The plats on which the corn was grown were 7 feet wide and 24 
feet long with a 4-foot walk dividing them. The land was plowed 
in the fall and left in that condition until spring when a mixture of 
fairly well-rotted horse and cow manure was applied to the various 
manured plats. In each ton of manure applied there were approxi¬ 
mately 738 pounds of dry matter, 3.04 pounds of phosphorus, 13.7 
pounds of potassium, and 16.08 pounds of nitrogen. The manure 
was thoroughly disked or plowed into the soil. Measured quantities 
of irrigation water were applied to the various plats as follows: 
4 plats received no water and no manure. 
2 plats received 5 inches of water and no manure; water applied in 2 equal appli- 
tions. 
2 plats received 10 inches of water and no manure; water applied in 2 equal 
applications. 
2 plats received 20 inches of water and no manure; water applied in 4 equal 
applicatons. 
2 plats received 30 inches of water and no manure; water applied in 6 equal 
applications. 
2 plats received 40 inches of water and no manure; water applied in 8 equal 
applications. 
On a duplicate series of plats, manure was applied at the rates of 
5 and 15 tons to the acre, the application of water being the same 
in every way as that on the unmanured plats. Hence the corn was 
grown on soils (1) without manure, (2) with 5 tons of manure to 
the acre, and (3) with 15 tons to the acre. The water applied 
varied from none to 40 inches, both with and without manure. How¬ 
ever, this does not represent the total water reaching the soil, for 
there was an annual average precipitation of about 18 inches which 
was the same for all plats. 
The irrigation water contained in each million parts 144 parts of 
calcium carbonate, 78 parts of magnesium bicarbonate, 3 parts 
of magnesium chloride, 7 parts of magnesium sulphate, 8 parts 
of sodium bicarbonate, 2 parts of sodium sulphate, and 2 parts 
of sodium chloride. Each acre-foot of the water carried to the soil 
2.2 pounds of potassium, 0.005 pound of phosphorus, and 1.1 pounds 
of sodium nitrate. Analyses of the son showed that during the 
course of the experiment, little of the nitrogen (7) and phos¬ 
phorus was being leached from the soil, but large quantities of 
the calcium magnesium and organic matter were disappearing. The 
analyses of the corn were made on composite samples taken from 
the various plats receiving the same treatment and from the 12 
yearly yields from 1911 to 1922. The analyses were all made in 
duplicate according to the official methods (f). 
NITROGEN 
The percentage composition of the dry corn kernel and the pounds 
per acre of nitrogen in the grain receiving various manure and irriga- 
