LIMING OF SOILS FROM A PHYSIOLOGICAL STANDPOINT. 27 
In experiments with maize, Knop found that the lime requirement 
of this plant is relatively larger than that of barley. From the data 
given the suitable proportion of lime to magnesia would be 1:0.25. 
Stohmann differs, however, on this point, and applies the ratio of lime 
to magnesia as 1:0.6. 
As to the tobacco plant, cultivated for its abundant foliage and topped 
to prevent seed production, it is natural to suppose that it requires 
more lime in proportion to magnesia than the cereals generally do. 
The percentage amounts of lime and magnesia from a number of ash 
analyses of tobacco leaf may here be mentioned. In 100 parts of ash 
are contained: 
Percentage of lime and magnesia in ash of tobacco leaf. 
Per centof Per cent of 
i 
Leat. lime. magnesia. 
eT SO es Se ee ee 31.12 8.58 
VDE Day PNET 0) See Se ee 47.27 10.16 
ea ee 2 ee 32.56 14. 69 
Ra So 2 i 37.36 6.37 
ees Lae NR ss ee nee eae baka aS e = hte 39. 39 9.35 
SPER E EE EUNR RD te ee a ees pa anne ------| 24-1 t060:3 {6110248 
(He TEP Tee te ee eS ee ee 39.53 9.61 
1Kissling, der Tabak, p. 41. 2 Botan. Jahresber., 1881. 
It will be seen from these few data that while the amounts of lime 
and magnesia show a wide range there is always a considerable excess 
of the former over the latter. It might not be far from the truth to 
assume that the average lime content of the tobacco leaf is about four 
times that of magnesia. This would agree fairly well with the ratio 
shown by the analyses of H. Smith of Massachusetts tobaccos. The 
soils. however. should contain still more than four times the amount 
of lime compared with that of magnesia. 
Comparing that ratio with that found in the tobacco soils consider- 
able discrepancies are observed. From analyses of tobacco soils pub- 
lished by William Frear’ the following data relative to the lime and 
magnesia content may be quoted: 
Percentage of lime and magnesia content of certain tobacco soils. 
- : Granville 
F Mil- | “A : 
Laneaster, Pa. New Mil County, Sumatra. 
ford, Conn. N.¢ 
Element. - av. U. 
E LEE HT: BV: a 
Per cent. Per cent. Per cent. Per cent. Per cent. 
ME en ee ee 2 0. 61 0.41 0. 32 0.07 0.77 
PMCID Fee es et 1.26 2.05 0.78 0. 02 0.37 
1The soil of Lancaster County limestone belt in its relation to tobacco culture, 
Penn. State College Ann. Rept., 1894, p. 160. 
