May 15,1925 
939 
Relation of Sulphur to Alfalfa Production 
determining the content of moisture, 
nitrogen, phosphorus, and sulphur. 
The method of treatment for the vari¬ 
ous series was as follows: 
No. 1, acid phosphate 400 lbs. per acre. 
No. 2, acid phosphate 400 lbs. and sulphur 384 lbs. 
per acre. 
No. 3, lime as calcium oxide 4,000 lbs. per acre. 
No. 4, sulphur 384 lbs. and lime 4,000 lbs. per acre. 
No. 5, sulphur 384 lbs. per acre. 
No. 6, 542 lbs. of N-P-K as 2-12-2, and lime 4,000 
lbs. per acre. 
No. 7, 542 lbs. of N-P-K as 2-12-2, 384 lbs. of sul¬ 
phur and 4,000 lbs. of lime. 
No. 8, manure 3,000 lbs. per acre. 
No. 9, manure 3,000 lbs. and sulphur 384 lbs. per 
acre. 
No. 10, manure 3,000 lbs., sulphur 384 lbs., and lime 
4,000 lbs. per acre. 
No. 11, control. 
No. 12, inoculated sulphur 384 lbs. per acre. 
The sources of fertilizing elements in 
the complete fertilizer were nitrogen 
from NaN0 3 , phosphorus from CaH 4 
(P0 4 )2, and potassium from KCl. The 
different materials were added to the 
pots and thoroughly incorporated with 
the soil before bringing the pots up to 
the optimum water condition. The 
alfalfa was then planted, November 
22 , 1922. Because of a delay in 
getting a supply of inoculated sulphur, 
series No. 12 was not seeded until 
December 6, 1922. Each pot was 
weighed twice per week and enough 
distilled water added to bring it up to 
weight. When the plants were about 
half grown they became infested with 
red spider. The only effective way of 
controlling this pest is a rather strong 
spray of cold water from a hose. The 
spraying has to be done every day the 
sun shines and, as a consequence, 
some water other than distilled water 
was applied in this way. The plants 
were allowed to grow until the majority 
were in full bloom when they were 
harvested, May 8, 1923. After record¬ 
ing the green weights, the samples 
were placed in a steam drying oven 
and the oven-dry weights determined. 
The method used in determining the 
content of nitrogen, phosphorus, and 
potassium was the same as stated in 
the manual of the Association of 
Official Agricultural Chemists, revised 
in 1919 ( 1 ). The magnesium nitrate 
method, as described by Swanson and 
Latshaw (17) was used in determining 
the sulphur content of the soil. The 
magnesium nitrate method, as de¬ 
scribed by Latshaw (8), was used in 
determining the sulphur in the roots 
and tops of the plants. The colori¬ 
metric method, as given by Schreiner 
and Failyer (14, p. 49), was used in 
determining the soluble sulphates of 
the soil. 
EXPERIMENTAL RESULTS 
The composition of the Oswego silt 
loam at the beginning of the experi¬ 
ment is as follows: Surface soil—total 
moisture, 19.31 per cent; nitrogen, 
0.228 per cent; phosphorus, 0.061 per 
cent; potassium, 2.119 per cent; total 
sulphur, 0.065 per cent; P H value, 7.016 
per cent; and soluble sulphates, 34.6 
parts per million. In general these 
figures agree rather favorably with re¬ 
sults of Swanson and Miller (16) but the 
potassium and sulphur content is some¬ 
what higher than that reported by 
these investigators. 
The mechanical analysis of Oswego 
silt loam as reported by the Bureau of 
Soils, United States Department of 
Agriculture, is as follows: Surface soil— 
fine gravel, 0.0 per cent; coarse sand, 
0.6 per cent; medium sand, 0.3 per 
cent; fine sand, 1.5 per cent; very fine 
sand, 6.9 per cent; silt, 71.8 per cent; 
and clay, 17.8 per cent. 
The daily minimum and maximum 
temperatures for the period of the ex¬ 
periment are shown in Table I. No 
records for the week ending December 
30, 1922, are available. 
The yields for the first and second 
cuttings of each treatment are given 
in Table II, in which it will be observed 
that the treatments which have given 
the greatest returns are lime, sulphur 
lime, and N-P-K with sulphur and 
lime (pi. 1). The difference in mean 
yield between the series named above 
in the respective order and the con¬ 
trol is 2.0, 3.0, and 3.9 gm. per pot. 
These treatments, however, do not 
give distinctly significant increases 
when the probable error calculated by 
Bessel’s formula is considered. 
The weight of roots for the various 
treatments are given in Table III. 
The probable errors calculated by 
Bessell’s formula are given for the 
yields but the numbers in which they 
are based are small and probably they 
should be used with caution in inter¬ 
preting the results. 
Acid phosphate and sulphur, sulphur, 
N-P-K with lime, manure, and in¬ 
oculated sulphur are treatments re¬ 
sulting in decreases in yield of alfalfa 
(pi. 2). Here again, the decreases are 
not significant on the basis of the 
probable error as calculated by Bessel’s 
formula. 
Considering root growth, as shown 
in Table III, there are not any signifi¬ 
cant increases in the effect of the 
various treatments, but three sig¬ 
nificant decreases: Acid phosphate; 
