1922] WOODARD—SOIL FERTILITY gI 
experiments were conducted in Indiana and Kentucky on the fields 
from which the soil samples were taken. 
SOIL ANALYSIS 
METHODS OF SAMPLING.—The soil samples from Michigan and 
Ohio (nos. 1-9) were taken by Dr. WiLtt1AM CrOcKER and those 
from Wisconsin (nos. ro-11) by Mr. E. H. Hatt. The samples 
were taken in the usual way by means of a soil auger. The samples 
from Indiana and Kentucky were taken when the soil was very 
wet, and as only the surface soil was sampled, it was believed that 
more accurate sampling could be done by using a spade or shovel. 
Some soil was removed to a depth of seven inches, leaving one side 
of the hole vertical, then a thin slice of soil was cut with the spade 
to the full depth of seven inches. A narrow strip of this extending 
from top to bottom was removed for the sample. Three or four 
such samples from different parts of the field were taken and mixed 
to form a composite sample. The samples from Indiana were 
taken by Joun Wooparp, except no. 18, which was taken by Mr. 
V. G. Mann, and those from Kentucky by Jon Wooparp, except 
nos. 32-34, which were taken by Mr. J. C. Gentry. All the soil 
samples were air dried, sifted through a 2 mm. sieve, and thoroughly 
mixed. 
ANALYTICAL METHODS.—Phosphorus was determined according 
to the official magnesium nitrate method of the Official Agricultural 
Chemists. A blank determination was run to determine the 
Possible presence of phosphorus in the chemicals, but no phos- 
Phorus was found. 
Sulphur was determined by a modification of the methods of 
SHEDD and of Brown and Kettocc. In preliminary work it was 
found that higher results were obtained when the iron and aluminum 
were removed. In soils low in sulphur the barium sulphate pre- 
cipitated very slowly, so, at the suggestion of Dr. FREDERICK 
Kocu,* rocc. of approximately N/1o H,SO, was added immedi- 
ately before heating the solution and adding the barium chloride. 
This sulphuric acid was measured in a burette, and exactly the 
* Unpublished work of Dr. FREDERICK Kocu. 
