Aug. i 9 ,1918 Availability of Potash in Soil-Forming Minerals 
3°7 
Xabl3 VII .—Weight of soybean crop and potash removed from soil —Continued 
Dry matter (grams). 
Potash removed from soil (grams). 
Treatment. 
Seed. 
Hay. 
Total, 
Aver¬ 
age 
total. 
Rela¬ 
tive 
rank 
of av¬ 
erage. 
Seed. 
Hay. 
Total. 
Aver¬ 
age 
total. 
Gain 
over 
no 
pot¬ 
ash. 
2*0 
11.0 
10 .8 
13-0 
12 .8 
1 
[O.046 
{ *oS 3 
0.086 
0.132 
[0.136 
p 0 ' . 
J- 13*6 
10.9 
.072 
• 125 
Do. 
3.6 
12.6 
15.2 
1 .062 
.091 
• i 53 
J 
Control (no potash) plus cal- 
S-o 
4.6 
17.6 
16.0 
22.6 
I 
[ .065 
.100 
.165 
l .161 
Do .. . 
20.6 
> 21.6 
i 7-3 
\ .058 
.096 
• 154 
0.025 
Do . 
4.0 
16.6 
20.6 
j 
| .062 
. 102 
.163 
J 
Control (no potash) plus 2 cal- 
4.2 
16.0 
20.2 
1 
f .062 
. 102 
. 164 
[ .166 
T)n . 
5 - 6 
18.3 
17-4 
23-9 
21.5 
> 21.8 
17-5 
-j .069 
. 106 
.175 
.030 
Do. 
4-0 
1 .060 
.099 
.159 
I 
The results shown in 
Table VII follow the 
same order regarding 
the relative availabil¬ 
ity of the insoluble pot- 
ashaswiththeoatcrop. 
Greatest growth has 
been obtained from bi- 
otite, then muscovite, 
orthoclase, and the 
least from microcline. 
Calcium carbonate 
has materially in¬ 
creased plant growth 
and the potash recov¬ 
ered in the crop when 
supplied with potas¬ 
sium sulphate, biotite, 
and muscovite; but 
to a much lesser extent 
with the feldspar and 
where no potash was 
added. This should 
not be taken to indi¬ 
cate that lime has been 
exchanged directly for 
potash in the applied 
minerals, but has pro 
2 POrASS/Wf SVIPPATE 
2 POTASS/i/Af SULPPATE+Ca CO3 
2 B/Or/TE 
2 BADT/TE+ Ca COj 
2MUSCOV/TE 
2 fiasco V/TE+ Ca co 3 | 
]* OPTNOCLASE 
|i? OPTHOCLASE+Ca CO 3 
J 2 M/CPOGL/PE 
1 SM/CPQCJJA/E+Ga CO 3 
] CQMTPOL 
COA/rPOL +Ca CO 3 
Fig. 2.—Rate of growth of soybeans under similar conditions fertilized 
with double applications of potash minerals and calcium carbonate. 
duced conditions in the soil more favorable to the growth of the legume. 
In this way hardier plants are produced which are capable of extracting 
more of this constituent from the minerals in which it is not so securely held. 
Figure 2 shows graphically the rates of the growth of soybeans ferti¬ 
lized with double applications of potash and lime. (See also PI. 49, B.) 
