16,5 Espino: Salt Requirements of Young Rice Plants 501 
Perhaps a recommendation as to the best set of salt propor- 
tions for this solution type for these young rice plants, etc., 
might be obtained by averaging these proportions, thus obtaining 
solution T1R1}S14, with molecular proportions 1:14:14:44. It 
may even be desirable to leave the relative value for magnesium 
sulphate as it is in R1S2 and R2S1 and allow the hypotheti- 
cally best solution to be T1R14S14, with molecular proportions 
1:13:14:4. Judging from the information at hand, either 
T1R14S14 or T1R14S14 should give excellent results for both 
tops and roots. There seems to be no reason for increasing 
the molecular proportional value of monopotassium phosphate 
above unity (one-eighth of the total molecular concentration of 
all salts taken together) for the hypothetical best set of propor- 
tions. 
From this generalization it appears that these young rice 
plants differ in their physiological salt requirements from many 
other plants, notably from wheat, buckwheat, and soy bean, es- 
pecially in the fact that the former need relatively a very high 
partial concentration of magnesium sulphate, and about equal 
and relatively very low partial concentrations of monopotassium 
phosphate and calcium nitrate. As has been seen, these rice 
plants are also peculiar in that they cannot develop satisfactorily 
when supplied with monopotassium phosphate, calcium nitrate, 
and magnesium sulphate in any possible proportions, but do 
develop excellently in the 4-salt solution type here employed, 
containing the three salts just mentioned and also ammonium 
sulphate. It may be of interest to note that the hypothetically 
best sets of salt proportions suggested above, TIR14S14 and 
T1IR14S14, are characterized by Ca:Mg ratio values of 14 : 43 
(1 : 3.250.308) and 14:4 (1 : 2.67=0.375), respectively. If 
we adopt the quite undesirable method of considering such ratio 
values as derived by considering the two metals as their oxides 
and employing the ratio of the weights of the oxides rather than 
the atomic or molecular ratio, it may be said that the atomic 
ratio Ca: Mg—0.308 is equivalent to the molecular ratio CaO :MgO 
=0.308, or the weight ratio CaO:MgO—0.375. The complete 
sets of atomic and ionic ratio values for the hypothetically 
best set of salt proportions T1R14S14 are as follows (neglecting 
the H-ion) : 
K: Ca: Mg: N: P: S=1: 14: 44: 54: 1: 5$. 
K: Ca: Mg: NH,: NO,: PO,: SO, = 1:14: 44: 23: 23: 1:53. 
