330 
Journal of Agricultural Research 
Vol. XXXI, No. 4 
1 gallon of solution per square foot. “ The solution should be put 
on with a watering pot with a rose and distributed as evenly as pos¬ 
sible over the bed so as to thoroughly wet the soil to a depth of a 
foot.” The writers’ experiments, carried out with various types of 
soil in different moisture conditions, show that there is considerable 
variation in the amount of solution necessary for thorough wetting 
of the soil to a given depth. Hartley (7, 8 , 9), the leading authority 
on damping-off diseases of forest-tree seedlings, recommends the 
application of 2 to 7 c. c. of concentrated sulphuric acid in 500 to 
1,000 c. c. of water per square foot of seed bed. He found that the 
amount of acid needed varies with the kind of soil, and the quantity 
of water required varies with the soil moisture. Hartley and Pierce 
say (8, p . 7): “ The disinfectant must be dissolved in sufficient water 
to permit its distribution through the soil to a depth of several inches, 
but within certain limits the concentration of the solution as applied 
does not appear to be an im por tant factor.” Most of the coniferous 
seed beds had sandy soils. Where the seed-bed soil was heavy and 
the addition of acia caused marked effervescence, indicating alka¬ 
linity, it was found that copper-sulphate solution gave better results 
than the sulphuric-acid application. 
Several others have earned on experimental work on the control of 
seed-bed and greenhouse diseases by complete or partial soil sterili¬ 
zation. 
Halstead ( 6 ) tried a variety of chemicals in soil treatments, but the 
applications of one-tenth gallon per square foot were inadequate for 
penetration beyond the surface few inches at most. None of the publi¬ 
cations consulted contain more than incidental and very general 
statements as to penetration. There were no data available that 
would enable one to plan soil treatments intelligently or with even 
a reasonable degree or assurance that important and variable factors 
had been taken into account. 
The present paper records the progress made in securing funda¬ 
mental data on the penetration of soil fungicides. The work mvolved 
the determination of satisfactory tests for the presence of certain 
chemicals in treated soil and the penetration of certain chemicals in 
different soils under different moisture conditions when different 
strengths and amounts of solution were used. Two improvements 
were made in the method of application of a water solution by the 
use of a cheap chemical to protect an expensive one in the solution, 
and by the application of these chemicals m part of the water followed 
by the remainder of the water to secure a more even distribution of 
the toxic chemical. 
APPARATUS, METHODS, AND MATERIALS 
A few preliminary experiments on formaldehyde penetration were 
made in the field near Freeland, Pa., in 1920. Most of the experi¬ 
ments were carried out in the laboratory at Washington, D. C. The 
use of laboratory methods and equipment made it possible to carry 
on the work during the winter and multiplied the amount and 
increased the accuracy of the data it was possible to secure. 
After consultation with some members of the staff of the Bureau of 
Soils, equipment was ordered, including soil tubes, sieves and shaker, 
compactors, balances, chemicals, and ordinary laboratory supplies of 
glassware. 
