A tig, 15, 1925 
Soil Disinfection for Potato Wart 
353 
Table XVIII. — Penetration of various amounts of water in Leonardtown silt loam 
containing 5,73 per cent moisture 
Penetration 
Amount 
added 
per 
square 
foot 
After 1 day 
One quart per square 
foot added after 
measuring and an¬ 
other measurement 
made the following 
day 
Increased second day 
over first 
Range ° 
Average 
Range 
Average 
Range 
Average 
Quarts 
Inches 
Inches 
Inches 
Inches 
Inches 
Inches 
a 1 
2y to 3J4 
3 % 
5 to 6M 
5 K- 
iyto 2 y 
2H 
2 
±y to sy 2 
5 y 
7 to sy 
7%— 
234 to 234 
2y 
3 
7V 2 to 8 
7 y+ 
9H to ioy 
10+ 
2y to 3 
iyto 3 
2y 2 
4 
m to 10M 
10- 
liy to 12M 
12M 
2y 
5 
9 y 2 to 12 
u 
i2M to uy 
13 
into 3 y 
2y 
6 
13M to 14 
13 H 
Penetration through column without 
addition. 
_* 
° Each of the six lots consisted of six tubes. 
SOIL PENETRATION OF OTHER CHEMICALS TESTED 
Soil Penetration op Water Solutions op Copper Sulphate 
Copper sulphate is such an old and much-used fungicide that a 
few penetration tests were run with it notwithstanding the well- 
known fact that copper sulphate solutions soon lose their copper 
sulphate when applied to soil. A 1 per cent solution of CuS0 4 failed 
to give a positive test after percolation 13 through 14 inches of potting 
soil. A 2 per cent solution failed to give a positive test after perco¬ 
lation through 14}^ inches of Manor loam. Six tubes were used in 
each of the above sets. Other tests with varying strengths of CuS0 4 
seemed to indicate that attempts to get penetration with CuS0 4 
alone in a solution were certain to fail. Since the addition of NaCl 
to solutions of HgCl 2 insures mercury penetration, it was thought 
that similar results might be secured by adding a salt toCuS0 4 
solutions. 
The first test of CuS0 4 with a salt was made with six tubes of air- 
dry Leonardtown silt loam, three treated 1 + 1 with 2 per cent CuS0 4 
+10 per cent NaCl and three treated 1 + 1 with 2 per cent CuS0 4 + 
5 per cent Na 2 S0 4 . At the end of four days the tubes treated with 
CuS0 4 +NaCl gave positive tests for copper at 6 to 7 (2 tubes) and 
7 to 8 (1 tube) inches and the tubes treated with CuS0 4 gave positive 
tests at 4 to 5 (1 tube) and 5 to 6 (2 tubes) inches. The results 
seemed very encouraging, especially those obtained with NaCl, so 
that the experiments were continued. 
The results obtained with Na 2 S0 4 were so poor that few tests were 
made with it. 
The penetration of CuS0 4 + NaCl was tested in 74 additional tubes 
with Leondardtown silt loam containing from 10 to 21 per cent 
moisture. Applications were made at the rate of 1 gallon per square 
foot in each case. The penetration obtained in these tubes ranged 
from 3 to 4 inches up to 9 to 10 inches, distributed as follows: 3 to 4 
inches (4 tubes), 4 to 5 (12 tubes), 5 to 6 (19 tubes), 6 to 7 (27 tubes), 
7 to 8 (11 tubes), 9 to 10 (1 tube). The penetration secured did not 
warrant the hope that the copper sulphate and salt solution could be 
expected to give adequate soil penetration to permit its use as a 
fungicide for potato wart. 
13 In percolation tests tubes were kept continuously supplied with solution until liquid began to drop 
at the bottom of the tubes. 
