34 
Vol. XXIII. No. I 
Journal of Agricultural Research 
Table III.— Hydrogen-ion concentration of cell sap as affected by the sulphate and the 
chlorid of potassium and other salts —Continued 
Fertilizer treatment of tobacco. 
Hy drogen-ion concentration of sap 
i collected at stated intervals. 
July ax. 
July 30. 
Aug. 6. 
Average. 
Special row tests: 
Control. 
200 pounds NaCl per acre. 
Control. 
Ph 
5.60 
! 5.85 
Pa 
5-43 
5 -63 
5.60 
5.62 
5-86 
5-85 
Ph 
5- 41 
5* 45 
Ph 
5-48 
5-64 
200 pounds NaaCog per acre. 
1 
Control. 
5- 79 
5- 95 
1,000 pounds CaCo 3 per acre. 
The complete fertilizer treatments of the plots used in the observations 
on hydrogen-ion concentration are given on pages 29 and 31. The 
data given in Table III show that there is a progressive increase in 
hydrogen-ion concentration of the leaf sap as the leaf advances toward 
maturity. This progressive increase in active acidity is markedly 
retarded by the sulphate of potassium and to a lesser degree by heavier 
applications of potassium and sodium chlorids. Neither calcium car¬ 
bonate nor sodium carbonate produced any marked effect. It is clear 
that the sulphate of potassium did not increase the active acidity and, 
in fact, it caused a considerable decrease in acidity. In these tests 
the leaves from plots treated with chlorids were free from sand drown, 
while the others, and especially those from the plots receiving sul¬ 
phates, showed evidences of the disease. Thus, while sulphates may 
promote the development of a pathological chlorosis they actually 
retard the normal yellowing of the leaf which is associated with ripening. 
The total calcium and the water-soluble sulphate (S0 4 ) were deter¬ 
mined in dried leaves from the plot treated with common salt and the 
control plot, as well as from the plots receiving 80 pounds potash per 
acre as sulphate and chlorid, respectively. The results are shown in 
Table IV. 
Table IV .—Influence of sulphates and chlorids on total calcium and 'water-soluble sul¬ 
phate in the dried leaf 
Fertilizer treatment of tobacco. 
t 
i 
Total ! Total 
ash in calcium 
leaves. | in leaves. 
1 
I 
Water- 
soluble 
sulphate 
(SOO in 
leaves. 
Control. 
200 pounds NaCl per acre.. 
! Per cent. 
! 13 - 06 
12.09 
8.89 
10. 50 
Per cent. 
1 3-46 
i -74 
1.40 j 
1.36 ! 
Per cent. 
I. 66 
♦67 
1 * 2 5 
I* 50 
80 pounds K z O per acre as chlorid. 
80 pounds K. 2 0 per acre as sulphate. 
It seems likely that the greatly increased growth of the plant resulting 
from the use of the sodium chlorid is largely responsible for the decrease 
in percentage content of calcium and soluble sulphate. The calcium 
content is the same in the plots treated with the sulphate and the chlorid 
