CAN SODA REPLACE POTASH AS A MANURE. 53 
rendered the nitrate of soda almost as efficaceous as the nitrate of 
potash. If it be asked, why, under these conditions the two nitrates 
produce the same effects or nearly so—we reply, because they act, 
in this case, simply by their nitrogen ; the soil being already liberally 
supplied with potash by the addition of the silicate. 
The following table exhibits these results, and shews the amount of 
influence due under these new conditions to the potash of the nitrate. 
The grains of wheat sown, amounted, as before, to twenty. 
A. 
Soil treated with phosphate of 
lime, nitrate of potash, and 
silicate of potash. 
I. 
Straw and roots...17gr.70 \ germs. 
215 grains of wheat..5°35) 23:05 
Il. 
Straw and roots... 17gr. et 
21°73 
207 grains of wheat..4°65 
Mean. 
Straw and roots...17gr.39 ] grms. 
211 grains of wheat..5:00 } 22:39 
Be 
Soil treated with phosphate of 
lime, nitrate of soda, and silicate 
of potash. 
I. 
Straw and roots... 15gr.25 ) grms. 
220 grains of wheat..4-45 ) 19.70 
Mls 
Straw and roots... 16gr.14 \ germs. 
201 grains of wheat.4gr.90 5 21.04 
Mean. 
Straw and roots...15gr.70 | grms. 
210 grains of wheat..4°67 J 20:37 
From the experiments described above, the following conclusions 
may be deduced : 
1. So far as regards wheat, soda cannot be employed as a substitute 
for potash : nitrate of soda associated with phosphate of lime, consti- 
tutes a manure of little efficacy. 
2. An addition of potash imparts to the mixture an immediate 
activity. 
3. If in practice, nitrate of soda has shown itself to be beneficial, 
this arises from the natural presence of potash in the soil. 
E. J. C. 
