110 
weight of K, 575 of Ca, 163 of Mg, 80 of N0 3 , 69 of HPO,, and 125 of SO,, and yet 
in each of these trials the layer of material through which the solution percolated 
was only about three-sixteenths of an inch thick. The solution passed through each 
time in less than fifteen minutes, and was in contact with the soil grains less than 
forty-live minutes. 
In other words, by using a solution of the same order of strength as that which the 
soil moisture would have possessed had it carried in solution all of the salts which 
were recovered by the eleven-times washing, the identical samples became again 
charged during the short treatment with from one to three times the amounts of each 
of the ingredients which had been recovered from them by eleven-times washing 
in distilled water. Even the freshly crushed granite charged itself, under the same 
treatment during the brief period of percolation, with more of each ingredient, except 
magnesia and SO,, than had been recovered, on the average, by the eleven-times 
washing of the S soil types. The solution, in percolating through the samples of the 
northern soils, lost nearly double the amount of potash that it did in percolating 
through the samples of the southern soils. 
Through determinations of the water-soluble salts carried in the sap of corn and 
potatoes growing upon the 8 soil types at the time the soil samples were taken at the 
close of three periods — 8, 12, and 14, taken June 15, July 13, and July 31, respectively — 
it was found that the plants of the northern soils carried as a mean 25,254 parts per 
million of their water-free dry weight of potash as against 23,900 parts per million 
carried by the plants of the southern soils; the lime stood 2,824 parts per million 
of the plants on the northern soils, and 1,891 parts per million of those on the south- 
ern; the magnesia stood 4,224 for the former and 1,753 for the latter; the NO s stood 
18,985 to 7,065; the HP0 4 , 5,374 to 5,263; the S0 4 , 3,243 to 1,939; the HC0 3 , 10,209 
to 9,418; the Si0 2 , 164 to 132, while the amounts of chlorin stood in the reverse 
order, 5,495 parts per million in the plants on the northern to 5,972 parts per million 
in those of the southern. It is also true that the amounts of chlorin recoverable 
from the southern soils have been found larger than those in the northern soils, 
although the amounts have been small in both cases. 
The mean total water-soluble salts was found to be 7.58 per cent of the dry weight 
of the corn and potatoes grown on the northern soils and 5.73 per cent of the dry 
weight of the plants grown on the southern soils. Since the dry matter produced on 
the northern soils has been more than double that produced on the southern soils, it 
follows that the absolute amounts of water-soluble salts recovered by the crops from 
the soils and still unassimilated at the times of the sampling must have been more 
than double from the northern soils what they were from the southern soils. We 
have here, therefore, an entirely independent line of evidence showing that there is 
a fundamental difference between these two groups of soils which has permitted the 
crops to acquire from the soil moisture in the same time more than double the 
amounts of w T ater-soluble salts from the northern soils of what were acquired from 
the southern soils. Such agreement, too, gives us confidence in the character of the 
plan of work followed through the season, in the reliability and sensitiveness of the 
methods developed for the work, and through it we are forced to see with what 
industry, skill, and faithfulness the essential details have been handled by the men 
who have done the work. 
In their relative capacities for nitrification, too, there has been found a marked 
difference between the four soils at the South and the four in the northern group. 
Samples from the surface foot of the eight types of soil brought to the optimum water 
content and kept for seventy days under like condition had acquired at the end of 
that time, as indicated by single three-minute washings in distilled water, for the 
northern soils, 169, 162, 177, and 143 parts per million of their dry weights of N0 3 
while the southern soils had acquired 70, 89, 71, and 121 parts per million of their 
dry weights of \( )., or an average for the four northern soils of 163 and for the 
four southern soils 88 parts per million, the northern soils having acquired double 
the amounts of N0 8 at the end of seventy days that the southern soils had acquired. 
Further than this, the two groups of soil differ in a marked way in the amounts of 
organic matter which they carry recoverable by washing in distilled water, the 
northern soils carrying much the larger amounts, but our methods for determining 
these amounts are not yet sufficiently perfected to give us reliable quantitative values 
to the differences between them. 
in regard to the difficulties with the southern soils and improvements in their 
management, it can be said that the most fundamental difficulty with them is their 
imperfect and feeble granulation. It is this imperfect and feeble granulation which 
gives the southern soils their great tendency to wash, their small and greatly sub- 
divided pore space, and consequent imperfect drainage, aeration, slow capillary 
movement of water, and the shallow depth of the root zone of crops. All of these 
differences conspire to give a low efficiency to the rainfall of the South and to force 
