322 
Journal of Agricultural Research 
VoI.XXIV, No. 4 
lives functioned in the same way. Sodium sulphate showed a very slight 
ameliorating action at i,ooo parts per million, at which concentration it 
appears to be decidedly stimulating to plant growth when added alone, 
but at higher concentrations it increased the toxicity of the carbonate 
(fig. 5, C). The mixtures of equal parts of two or three sulphates were 
all somewhat beneficial, but the presence of sodium sulphate noticeably 
reduced the corrective power of the mixture in proportion to its concen¬ 
tration (fig. 5, D). All the observations that have been made with the 
sandy soil can be readily explained by the simple ionic reactions between 
the added substances, and, accordingly, this case is not essentially differ¬ 
ent from a solution culture. 
I 
/o 
t 
/s 
/o 
I 
A/ao cqs 
200 ^ aooo 
> 
/ 
\ 
• 
/ 
Ml. 
tCC 
b 
Mg 
\l 
V 
V 
• 
\ 
• 
♦ 
< 
/? 
2000 5000 6000 
* 
A 
1 
0 
% 
9 no 
Mii 
0 
i 
% 
\* 
\o 
w 
% 
'On 
\6 
s 
!S&a 
/5 
to 
5 % 
B 
BBM. A/a,p CO3 
2000 5000 6000 
i 
- W<L. 
'o»o<|^^, 
tSO^-f-CeLSO, 
0^ f'Ox 
'Jr 
rwx 
loo 
Ck ' 
^ tl V 
/3 
Pio. 9.—Diagram showing the efifect on the growth of wheat plants of adding sulphates to sand impregnated 
with an equal total quantity of sodium carbonate. 
In figures 3 and 4 are shown the results obtained when the previously 
mentioned materials were added to Greenville loam and West Logan 
clay loam, respectively. Both soils behave similarly and may be 
conveniently discussed together. As in the case of sand, neither 
the sulphuric acid nor the calcium sulphate is toxic at any of the con¬ 
centrations used. The sodium sulphate begins to reduce the growth of 
the plants appreciably at about 5,000 parts per million, and the mixtures 
of this salt with sodium carbonate show decided additive toxicity except 
possibly at the lowest concentrations. For example, the dry weight 
per plant in Greenville soil is reduced to one-half normal (6.7 mgm.) 
