Oct. 4. 19IS 
Effect of Alkali Salts in Soils on Crops 
9 
Table VI.— Percentage of germination of New Zealand wheat in soil containing alkali 
salts in different quantities. Salts added dry 
Sodium chlorid. 
Sodium car¬ 
bonate. 
Sodium sul¬ 
phate. 
Magnesium sul¬ 
phate. 
Equal parts of 
sodium chlorid, 
sodium carbon¬ 
ate, sodium sul¬ 
phate, and mag¬ 
nesium sul¬ 
phate. 
Equal parts of 
sodium chlorid, 
sodium carbon¬ 
ate, sodium sul¬ 
phate, and mag¬ 
nesium sulphate 
+ 1 per cent of 
calcium sul¬ 
phate. 
Seed 
Seed 
Seed 
Seed 
Seed 
Seed 
ger- 
ger- 
ger- 
ger- 
ger- 
ger- 
P. p. m. 
mi- 
P. p. m. 
mi- 
P. p. m. 
mi- 
P. p. m. 
mi- 
P. p. m. 
mi- 
P. p. m. 
mi- 
21 a- 
na- 
na- 
na- 
na- 
na- 
tion. 
tion. 
tion. 
tion. 
tion. 
tion. 
P. ct. 
P. ct. 
P. ct. 
P. ct. 
P. ct. 
P. cf. 
None. 
92 
None. 
92 
None. 
92 
None. 
92 
None. 
92 
None. 
92 
800 
81 
10,000 
81 
2,000 
80 
12,000 
86 
4,000 
77 
1,000 
77 
1,600 
82 
11,100 
64 
4,000 
83 
14,000 
79 
5,000 
78 
2,000 
79 
2, 400 
76 
12,200 
66 
6,000 
85 
16,000 
75 
6,000 
54 
3,000 
79 
3,200 
50 
i3>3°o 
32 
8,000 
79 
18,000 
82 
7,000 
5 i 
4,000 
79 
4,000 
13 
14,400 
So 
10,000 
69 
20,000 
81 
8,000 
76 
5,000 
73 
4,800 
6 
15 , 500 
3<5 
12,000 
43 
22,000 
78 
9,000 
19 
6,000 
75 
5,600 
7 
16,600 
3» 
14, 000 
20 
24,000 
87 
10,000 
12 
7,000 
68 
6,400 
0 
17, 700 
23 
16, 000 
16 
26,000 
66 
11,000 
6 
8,000 
46 
7, 200 
0 
18,800 
r 3 
18,000 
3 
28,000 
S<5 
12,000 
10 
9,000 
38 
8,000 
0 
19,900 
1 
20,000 
0 
30,000 
57 
13,000 
1 
10,000 
13 
An examination of Table VI, in agreement with Table V, shows the 
germination to be greatly reduced by sodium chlorid in concentrations 
above 3,000 p. p. m., while it ceases entirely at about 6,000 p. p. m. 
With sodium carbonate a large reduction in germination occurred at 
about 10,000 p. p. m., but a few plants survived at about 20,000 p. p. m. 
The sodium sulphate showed about the same results as the sodium car¬ 
bonate, while the magnesium sulphate gave over a 50 per cent germina¬ 
tion at a concentration of 30,000 p. p. m. In the mixed salts the gyp¬ 
sum (calcium sulphate) did not have any great effect, possibly owing to 
the slowness with which gypsum dissolves. 
On comparing the data in Tables V and VI with those reported in 
Table I and also others given later in the paper, where the salts were 
first dissolved and added in solution, it will be found that the salts were 
more toxic when added in solution than when mixed with the dry soil. 
This may be due to the slow solution and diffusion of the salt when added 
dry, which probably helps to explain the common observation that 
crops can sometimes be made to grow in a soil the analysis of which 
shows a very high total alkali content. It also explains why it is that 
crops growing on alkali land may look healthy and be growing vigor¬ 
ously until irrigated, when they are immediately killed. 
In order to determine more exactly the effect of soil moisture on the 
toxicity of alkali salts, sand was placed in tin plates, as previously 
