EXPERIMENTAL STUDY. 49 
It will be observed that the amounts of soluble salts in this experi- 
ment were very largely in excess of the needs of the plants. They 
were made so in order to thoroughly test the capacity of the lime in 
counteracting the noxious influence of the magnesia, and the bases 
were not added with the view of conserving the best conditions of 
plant growth or with the idea of bringing them to their full develop- 
ment. 
- The experiments tend to show that the most favorable condition for 
the growth of wheat is in the soil where the amount of available lime 
is in moderate excess over the amount of available magnesia. If the 
amount of magnesia is too small in the presence of a larger percentage 
of lime the plant shows phenomena, apparently, of starvation. If the 
amount of magnesia is excessive, with a deficiency of lime, the mag- 
nesia exerts a poisonous influence upon the plant. 
The Deutsche Landwirtschaftliche Presse’ states that calcium car- 
bonate in the soil to the amount of 0.46 per cent had an injurious effect 
upon lupins, and that this was overcome by an application of kainit. 
The action of kainit in this case was probably due to its magnesia 
content. 
In a trial with oats in these series of pots the results were as with 
_ wheat—the germination was quickest and growth best in the pots with 
MgO 0.4 and CaO 0.5 per cent. 
EXPERIMENTS WITH COWPEAS. 
After the removal of the wheat one series of pots was planted to 
cowpeas and one to tobacco. With the cowpeas the results of the 
most favorable ratio of lime to magnesia was the same as with wheat. 
The seed germinated in the same order, the ratio of CaO 0.5 and MgO 
0.4 being the more favorable, and the growth of plants decreasing 
from that pot to the two extremes. The cowpeas, however, appeared 
to be more tolerant of the excess of the two salts in the extreme pots, 
and after germination the plants grew better than the wheat plants. 
Since the cowpea contains more of the mineral nutrients stored up in 
its seeds than wheat grains, the evil effects of an excess of magnesia 
or lack of lime in the soil can be better counteracted up to a certain 
stage in the development of the plant. 
EXPERIMENTS WITH TOBACCO. 
To the second series of eight pots tobacco plants about 5 em. high 
were transplanted from soil. Beginning with the pot containing 
~ CaO 0.8 and MgO 0.1 per cent, the plant started into quickest growth, 
showing the greediness of this plant for lime. Later, however, this 
plant became spindling and of light color, while the plants in the pots 
1Vol. 23, Nos. 91 and 92. 
4(84—_ No. 1—01——4 
