Arsenic Toxicity Studies— Clements and Munson 
16! 
* SO/L - CULTURE CAM MUM BCR 
Fig. 1 . Green weights and arsenic content of tomato plants grown in red soil with arsenic content 
ranging from 15 ppm (Can 1) to 3,014 ppm (Can 24) of As 2 0 3 . The difference in levels of the two 
green-weight curves is due to the season in which the plants were grown and is not related to treat¬ 
ment. (For As 2 0 3 increments, see Table 7.) 
was added weekly to the soil. Each crop 
was allowed to grow 31 days from the time 
of transplanting, after which the plant tops 
were collected and green weights obtained. 
The material was dried, ground in a Wiley 
mill, and stored for future analysis. 4 
After the removal of one crop, the soil 
was allowed to dry thoroughly, after which 
each can was emptied and the soil pulver¬ 
ized, mixed, and returned. Roots were in 
each case returned to the bottom of the can. 
Results and discussion: Tomato .—The data 
4 All the arsenic analyses made in connection 
with these soil studies were made by the Chemis¬ 
try Department of the Experiment Station, Ha¬ 
waiian Sugar Planters’ Association. The depart¬ 
ment is directed by Dr. F. E. Hance, to whom sin¬ 
cere thanks are due. 
presented in Table 7 and shown in Figure 1 
for tomato plants in red soil reveal the rela¬ 
tive tolerance of young plants to soil arsenic 
up to approximately 514 ppm. At higher 
levels the ability of the plant to grow is dras¬ 
tically reduced to what would be growth 
failure in a commercial field. 
At levels below 514 ppm, growth of the 
tomato is approximately at uniform levels, 
no matter what the level of arsenic in the 
soil. While there may be some slight evi¬ 
dence of stimulation, it is very inconclusive. 
The arsenic content of the plant tissues 
varies between 2 and 3 ppm for soil levels 
of arsenic between 15 and 314 ppm. Between 
this point and approximately 414 ppm of 
soil arsenic, the arsenic level rises gradually 
