107 
The total evaporation from a continuously capillarity saturated surface of the soil 
evaporimeter at Goldsboro was 23.92 inches between May 1 1 and September 22, or at 
the mean rate of 2. 12 inches, or 11 pounds per square foot per ten days; at Upper 
Marlboro the rate was 1.92 inches, or 9.8 pounds per square foot per ten days; at 
Lancaster the rate was 1.53 inches, or 7.96 pounds per square loot per ton days, and 
at Janesville it was 1.8 inches, or 9.38 pounds per square foot per ten days. The 
number of inches of water evaporated from the four evaporhneters stands: 23.92 
inches for the one at Goldsboro; 27.27 inches at Upper Marlboro; 21.74 inches at 
Lancaster, and 25.26 at Janesville. 
From areas exactly equal to those of the soil evapori meters and of the same soil, 
but upon which ten stalks of the "Iowa Gold Mine" corn matured, the total evapo- 
ration at Goldsboro was 25.07 inches, where the yield computed per acre and at 15 
per cent moisture of ears and stalks was 9.8 tons; at Upper Marlboro the evapora- 
tion was 20.23 inches for a yield of 2.6 tons per acre; at Lancaster it was 24.49 inches 
for 7.4 tons per acre, and at Janesville 26.81 inches for a yield of 12 tons per acre of 
ears and stalks computed to 15 per cent of moisture. These yields per acre on the 
evaporimeters are from one and one-half to four times that secured from the fields on 
the subplats to which no fertilizers were added. These relatively large yields are 
due to the facts that only the surface 9 inches of soil were used to till the evapori- 
meters, that more plants were grown per unit area, and that a constant supply of 
water was maintained in the soil. A closer stand upon the ground was made in 
these trials, because it was desired to tax the capacities of the different soils to their 
maximum limits of production, the comparative feeding power of the soils being the 
primary object of this series of observations. In order that an abundance of sun- 
shine should be provided for this closer stand, the evaporimeters were located on the 
fallow ground rather than in the cornfields surrounded by the field corn. 
When the rate of evaporation is expressed in inches per day for the whole period 
of growth of the crop it is found to be at the rate of about 2.4 inches per ten days at 
Goldsboro, 1.6 inches at L T pper Marlboro, and 1.8 inches for both Lancaster and 
Janesville, computed to the actual area of the soil occupied by the plants. The rate 
of evaporation at Janesville was a little higher than that at Lancaster, the difference 
being about 2 per cent. The rate at Goldsboro, however, was appreciably higher 
than either of the other places, it being about 20 per cent above the average for 
Lancaster and Janesville. 
From these results it appears that for the United States east of the Mississippi the 
mean rate of evaporation from June to September, inclusive, from a wet-soil surface, 
kept saturated capillarity, is not very different in different portions, and that the 
average is about 0.96 of a pound per square foot per day, or 0.19 inch. 
The mean field yields secured from the eight soil types, placing the four southern 
soils in one group and those of the North in a second group, stand: 33.586 bushels to 
64.324 bushels of shelled corn per acre, computed to 10 per cent moisture, and 78.356 
bushels to 213.146 bushels of potatoes per acre. It is thus seen that the yield of corn 
on the northern soils has been nearly double and that of the potatoes has been 2.7 
times the yield of the southern soils, or for the two crops combined the northern 
soils have given a mean yield in bushels per acre 2.47 times the yield secured from 
the southern soils under conditions in every way alike, except those due to climatic 
differences. These ratios of yield are clearly not the results of bad management of 
the southern soils, because for both corn and potatoes they have been notably larger 
than those usually obtained. The yields of the northern soils, while good for the 
corn, are not large for favorable conditions, and for the potatoes the yields are small 
rather than good for favorable conditions of growth. It is perhaps not improbable 
that the smaller yield of potatoes at the South has been partly the result of a too high 
soil temperature, but otherwise the temperature relations have been more favorable 
to goodyields in the South than in the North. The distribution and quantity of rain- 
fall during the growing season was generally favorable to good yields, except at Lan- 
caster, where the early season was too dry and the later too wet and cold. The rainfall 
at the four stations between April 29 and September 10 was 19.44 inches at Golds- 
boro, 19.78 inches at Upper Marlboro, 18.87 inches at Lancaster, and 18.75 inches at 
Janesville; and there was no period of ten days after May 24 with less than 0.35 inch 
of rain at either station. So, too, there was no 10-day period at either station with 
more than 3.84 inches, while the heaviest rainfall during any one day was 2.52 inches 
at Lancaster. 
The absolute amounts of soil moisture carried by the different soil types, when 
expressed in inches for the surface 4 feet, have not been very different, the total 
mean for the season in the surface 4 feet having been 13.37 inches in the southern 
soils and 14.76 inches in the northern, making a total difference of only 1.39 inches, 
or the equivalent of 0.45 inch of rainfall per foot of depth. In the surface foot the 
northern soils have carried a mean of 3.03 inches of soil moisture, while the southern 
