28 RELATION OF LIME AND MAGNESIA TO PLANT GROWTH. 
‘The lime content of these soils is not only very low when the high 
lime requirement of the tobacco leaf is considered, but in the first three 
cases of the five mentioned the soils contain less lime than magnesia. 
Lime would prove of great benefit here, avoiding, however, magnesian 
limestone. On soil IV, however, magnesian limestone may be suc- 
cessfully applied. ; 
Tobacco soils in general must possess not only a proper chemical 
composition, but also a very satisfactory mechanical condition.’ 
The rapid growth and the relatively large leaf surface make tobacco 
more susceptible to the mechanical condition of the soil than most 
crops, since the roots require conditions for a rapid spreading. It 
would. be of considerable interest in this regard to make a comparative 
investigation of the soils of Vuelta Abajo and Vuelta Ariba in Cuba. 
The two valleys are not separated by a great distance, but the former 
produces a tobacco far superior to that of the latter. 
That certain chemical qualities of tobacco are dependent upon a 
certain ratio of lime to magnesia seems to receive an illustration from 
the fact that in Italy the soils for raising tobacco are exceedingly rich 
in lime and sometimes very poor in magnesia. There it was observed 
that tobacco called Spagnuolo develops better odor (but not always a 
better aroma in smoking) when the amount of magnesia was increased 
by irrigating with water containing magnesium salts.” This is also 
asserted for the Shiras tobacco from Persia.’ 
The grape also requires a considerable amount of lime, exceeding 
very much that of magnesia, as seen from the following data taken 
from Wolff’s Tables: * 
Percentages of lime and magnesia required by the grape. 
| 
F . -= || otal ashi | 
= 4 >) y ag aS é | s 3 
Parts of vine, etc. | ae oete lagnesia 
F ; ae indry ~| 
| the ash. inthe ash. anit i 
Per cent. Per cent. Per cent. | 
Foliage (inpAwe ust) li e22 seis eee eee oh s ee eal 25. 69 10.30 | 1.45 | 
Wioo Gin Heb rulaiy)\ les Sees eee eeleere aae seta aeieee 30. 41 7.19 oT 
Wie URiesling titer tee sen a Ase soe te kee, sears eed 7.43 0.67 | 0. 28 
Upper wood ossoiar 22 Sake tee Sma oeie pe reee oe eee 40.17 6.17 2.91 
WOWErswiO0Odstisesae see ane e eee e Pe tet ee rere eae 37.92 8. 24 2.70 
Upper leaves ae eee ae nens PAGO LDC TWA pple 48.17 7e350 | 6.96 
ONE letnyCles eka cdsues -cdassscteaace eae ena See | 50. $9 7,00 | 8.47 
1 The soil from which these samples were derived contained 0.018 per cent of lime and 0.002 percent 
of magnesia, both soluble in cold concentrated hydrochloric acid. 
1Compare especially the publications of Milton Whitney on tobacco soils, Bul. No. 
4, Weather Bureau, and No. 11, Division of Soils, U. S. Dept. Agr. The above 
remarks are made for the condition that the hme and magnesia content are equally 
well assimilable in these soils. 
*Sparano, Guida Agrario-Meteorologica, Roma, 1899. 
3 Kew Garden Bulletin, 1895. 
* Aschen-Analysen, II, Berlin, 1880. 
