688 
Journal of Agricultural Research voi. xxvii, no. 9 
injurious concentrations in the soil. Where the soil is rich in calcium 
carbonate, the use of either sulphuric acid or elemental sulphur may be 
expected to result in the solution of calcium with consequent beneficial 
effects. 
It seems certain that when sulphuric acid is applied to the soil either 
directly or through the use of elemental sulphur, the reactions are not 
confined to the soil solution. For example, if it were found by analysis 
that a certain soil contained a certain proportion of dissolved bases in 
excess of the dissolved acids, that is, carbonates, and a quantity of 
sulphuric acid equal to that excess were added to the soil, it would be 
found that only part of the acid had displaced the carbonate from the 
solution and that the remainder had reacted with the soil to bring an 
additional quantity of bases into solution. If one were to extract a 
sample of the soil solution from that soil and add the acid to the solution 
the carbonates would be completely displaced and the solution made 
neutral, but when the solution remains in the soil this is not the case. 
This point deserves special emphasis because it has not been clearly 
understood. It has been natural to regard the soil as a mass of inert 
material holding a certain quantity of a solution, very much as a solution 
is held in a beaker, and that this solution could be titrated in the field 
in quite the same way as it could be titrated in the laboratory. 
The experiments of Kelley and Thomas already referred to afford an 
excellent opportunity to illustrate this point that the acid reacts not only 
with the solution but also with the soil. One of these experiments 
involved the application of elemental sulphur to a sample of soil which 
was then moistened to optimum condition and kept at room temperature 
for 15 weeks. The soil was analyzed for all its water-soluble constituents 
before treatment. After treatment the water soluble C 0 3 , HC 0 3 , S 0 4r 
and Ca were determined. The analyses before treatment showed that 
the total of the reacting values of the soluble acids was 169.2 per million 
of dry soil. The soil also contained calcium as calcium carbonate in¬ 
soluble in water but soluble in 4 per cent HC 1 equivalent to a reacting 
value of 282 per million. Equal portions of the soil were treated with 
three different quantities of elemental sulphur, as shown in Table XXX, 
which also gives the quantities of the soluble constituents identified at 
the conclusion of the experiment. 
Table XXX .—Effect of elemental sulphur on alkali soil, the sulphur used and the solu¬ 
tion constitutents being expressed as reacting values based on the dry soil. a 
Soil No. 
Sulphur 
added. 
r Acid 
required. 
Loss. 
r Ca. 
Gain. 
r SO4. 
Gain. 
905 . 
None. 
12. 5 
25. 0 
5 o* 0 
17. 0 
10.3 
8.5 
7. 6 
6. 7 
8-5 
9. 4 
0. 25 
I. 70 
3. 00 
6. 60 
!-45 
2- 7 S 
6 -35 
74. O 
86. 1 
94 - 5 
120. 7 
12. I 
20. K 
46. 7 
o From Kelley and Thomas. 
The results given in Table XXX show that a large proportion of the 
sulphur applied to the soil was oxidized into S 0 4 , which enriched the solu¬ 
tion correspondingly. In the sample of soil to which 12.5 units of sulphur 
were added the dissolved sulphates were increased 12.1 units. The solution 
