Mar. 1, 1925 
Effect of Sulphur and Gypsum on Palouse Silt Loam 461 
in plotting the curves shown in Figure 
1. The graph permits a comparison of 
the results obtained from both experi¬ 
ments, and also shows the relation of 
sulphofication to the availability of the 
soil potassium, magnesium, calcium, 
and nitrogen. 
By examining the curves represent¬ 
ing the different elements, and com¬ 
paring the inoculated sulphur with the 
uninoculated sulphur, it is seen that, 
in general, the line connecting the two 
sulphur treatments is nearly always 
parallel to the abscissa. Especially is 
this true for the small applications of 
sulphur. It seems well established, 
therefore, that the uninoculated sul¬ 
phur produced about the same effects 
in this soil as did the inoculated sul¬ 
phur. 
The curve representing the water- 
soluble calcium from the greenhouse 
pots follows the same general conform¬ 
ity as the sulphur curve for the green¬ 
house soils. This shows that with in¬ 
creased sulphofication there was a cor¬ 
responding increase in the loss of cal¬ 
cium from the soils receiving sulphur, 
and this loss was greater with the high 
applications of sulphur than with the 
low sulphur treatments. The calcium 
curve for the field pots is apparently 
abnormal, or contrary to what would 
be expected to follow from the applica¬ 
tion of sulphur to the soil. The po¬ 
tassium curves show that increased 
sulphofication was followed by a greater 
availability of the soil potassium. Gyp¬ 
sum caused no marked effect on the 
water-soluble potassium, except under 
greenhouse conditions. 
The curves representing the water- 
soluble magnesium obtained from the 
soils in both experiments show that the 
sulphur treatments had little effect on 
the loss of magnesium in the drainage 
water, except in the case of the large 
applications made on the greenhouse 
soils. The nitrogen curves likewise 
show that the applications of sulphur 
and gypsum had little effect upon nitri¬ 
fication. 
CONCLUSIONS 
From the data secured from this 
work on the Palouse silt loam, and 
presented in the foregoing tables and 
in Figure 1 (see p. 462), the following 
conclusions seem to be justified: 
(1) The Palouse silt loam has a 
naturally high sulphofying power, and 
uninoculated sulphur when added to 
this soil was just as efficient as inocu¬ 
lated sulphur in producing sulphates. 
(2) Under the conditions of the ex¬ 
periments the gypsum and sulphur 
used as fertilizers were readily leached 
out during the winter months. To 
guard against unnecessary losses of 
these materials it is advisable to apply 
them at a time when the crop has the 
greatest need for them. 
(3) All of the sulphur treatments 
increased the availability of the native 
soil potassium, as is evidenced by the 
increased amount of this element in the 
drainage water from the soils which 
were treated with sulphur. Gypsum 
increased the amount of soluble potas¬ 
sium under greenhouse conditions, but 
definite increases in soluble potassium 
were not obtained under field conditions. 
(4) Elemental sulphur, when oxi¬ 
dized in the soil under greenhouse 
conditions increased the loss of calcium 
in the leachings. The results on cal¬ 
cium obtained under field conditions 
vrere too irregular to point to any con¬ 
clusions. 
(5) Magnesium compounds in the 
soil were but little affected by sulphur 
or gypsum. 
(6) Both the sulphur and gypsum 
treatments had little effect upon 
nitrification in this soil. 
