16, 6 
Espino: Salt Requirements of Young Rice Plants 483 
phate, while calcium nitrate seems to constitute a corresponding 
limit for rice; if the soy-bean diagram were rotated a third of 
a revolution in the clockwise direction it would correspond very 
closely to the rice diagram. 
The points just brought out emphasize what seems likely to 
be a very important general principle in the science of plant 
nutrition ; namely, that different plant forms may require entirely 
Shive, wheat, 1.75 atmospheres. Shive, soy bean, 2.5 atmospheres. 
Shive, buckwheat, 1 .75 atmospheres. Espino, rice, 0.23 atmosphees. 
Fig. 3. Good and poor sets of salt proportions for four plant forms. 
different sets of salt proportions for good physiological balance. 
The comparison just made involves only four plants and no two 
show a tendency to agree as to the solution characteristics that 
give best growth. It is of course to be expected that, as the 
salt requirements of other plants are made known, and as those 
of the plants here considered become better understood, it will 
be found that there are a number of types of salt requirement. 
