26 
Journal of Agricultural Research 
Vol. VIII, No. i 
The average variation (i part in 25) in the potash content is well 
within the experimental error, when the lack of uniformity in the soil 
and the analytical difficulties are considered. There is no evidence that 
the addition of calcium sulphate modified to a measurable degree the 
solubility of the potash in this soil. 
Another soil from the Oatman tract, about 7 miles from Riverside, 
was treated with calcium-sulphate solutions in the same way. This soil, 
which had been under cultivation for a number of years, was more 
granitic in character and less weathered than the virgin soil. The potash 
solubility in varying concentrations of calcium sulphate is shown in 
Table VII. Here, again, there is no indication of any replacement of 
potash by the lime; but, on the contrary, the addition of calcium sulphate 
depresses the solubility of the potash, as was found in the case of orthoclase 
(Table IV). 
Table VII .—Effect of solutions of calcium sulphate on the solubility of potash in Oatman 
soil 
Solution No. 
Calcium sul¬ 
phate in 100 c. c. 
of solution. 
Potassium 
oxid in 
solution. 
I. 
Gm. 
0, 00 
P. p. m . 
8.6 
8.6 
8. 0 
A. -2 
2 . 
. 017 
. 0*1/1 
2 , , ’. 
A . 
. 068 
c... 
. 102 
2 , 2 
6. 
. 136 
. I70 
a . 210 
2.2 
7. 
2.4 
4.2 
S. 
a Solid phase present. 
LeClerc and Breazeale 1 have shown that the sprouting seedling of 
wheat manifests a strong demand for potash, entirely out of proportion 
to its demand for nitrogen and phosphoric acid. When potash is pres¬ 
ent in a readily available form, the young wheat seedlings, during the 
first three weeks of growth, will often take up an amount of potash 
(K 2 0 ) equivalent to 8 per cent or more of their dry weight. This 
avidity of the plant for potash was made use of in the following manner: 
Wheat seeds were sprouted on perforated aluminum disks floating in 
large pans. Each pan contained about 1,000 seeds. When the shoots 
had reached a length of about 2 cm., the plants were taken up, a few 
at a time, and transplanted to other disks, floating in the various solu¬ 
tions listed in Table VIII. In this way all the unsprouted seeds were 
eliminated, which would otherwise have become a source of.potash. 
The solutions in the pans were stirred frequently and the plants were 
1 LeClerc, J. A., and Breazeale, J. F. Translocation of plant food and elaboration of organic plant mate¬ 
rial in wheat seedlings. U. S. Dept. Agr. Bur. Chenl., Bui. 138, 32 p., 2 fig. 1911. 
