44 HARPER: VEGETATION OF THE PINUS TAEDA BELT 
Data for estimating the average chemical composition of the 
soil are rather meager. In the Tenth Census, vol. 6, pp. 504 and 
556, are analyses of seven soils from this region (five from North 
Carolina and two from South Carolina), made by Hilgard’s five-day 
acid digestion method, which seems to give results more consistent 
with the vegetation and crops than any earlier or later method. 
Details of the locality, depth, vegetation, etc., of each soil are 
given in the work mentioned (under Nos, I and 9 on page 504 and 
II, 13, 15, 17 and 19 on page 556), and need not be repeated here. 
The averages of the seven analyses are given below. (With so 
few samples from South Carolina and none from Virginia it would 
hardly be worth while to give the averages for each state sepa- 
rately.) 
Per cent. 
Water and organic matter... ose esi ee os ees 2.940 
POUASIE CRON, aoe erie Set nc ooo res be bw ee I25 
RSA ON MO ec eae ees Ce oe de RE 052 
PoP CAG) iy ote Ae oe 2k eee CU nie 079 
agate Cte0) Ree either te eS ty i ga 076 
SIG TE WOn). Soc i a ones .082 
Suiphurfe acid sadicle (BOs) ee es -085 
Brown oxide of manganese (Mn:0,4)............ -068 
Peroxide. of ivot (hess) eeu at oe 1.684 
wc bistindtin CAN 2 ooo ens ve hao oe og ES 3-375 
Soluble silita. ¢ ioc e se can es ar ae 2.704 
Pnsoiuble ninttero. 0 er oo ek ee a 88.844 
These figures of course will mean little to one who is not accus- 
tomed to interpreting soil analyses, but those who are sufficiently 
interested may find it worth while to compare them with similar 
analyses from other states published in the same work and copied 
by the writer in recent easily accessible publications.* Even yet 
the significance of some of the figures cannot be explained, for 
lack of knowledge of the functions of some of the soil constituents 
in plant physiology; but there is no doubt that these soils are 
below the average for the United States in fertility. 
It seems very probable that the Virginia portion of this belt has 
a higher proportion of potassium in its soil than the rest, on 
account of the proximity to metamorphic rocks and the drier 
summers, and more humus on account of the richer soil and less 
* Bull. Torrey Club 40: 380-391. 1913; 41: 555- 1914; Rep. Fla. Geol. 
Surv. 6: 195, 230, 269, 328. 1914; 7: 123. IQI5. 
