190 HOW CROPS FEED. 
acter of the latter determines to a certain degree the na: 
ture of the atmospheric changes. In case of many crops, 
the soil is but partially covered, and its peculiarities are 
then of direct influence on its temperature. 
Relation of Temperature to Color and Texture,—lIt 
is usually stated that black or dark-colored soils are sooner 
warmed by the sun’s rays than those of lighter color, and 
remain constantly of a higher temperature so long as the 
sun acts on them. An elevation of several degrees in the 
temperature of a light-colored soil may be caused by 
strewing its surface with peat, charcoal powder, or vege- 
table mould. To this influence may be partly ascribed 
the following facts. Lampadius was able to ripen melons, 
even in the coolest summers, in Freiberg, Saxony, by 
strewing a coating of coal dust an inch deep over the ‘sur- 
face of the soil. In Belgium and on the Rhine, it is found 
that the grape matures best, when the soil is covered with 
fragments of black clay slate. 
According to Creuz¢é-Latouche, the vineyards along the 
river Loire grow either upon a light-colored calcareous 
soil, or upon a dark red earth. These two kinds of soil 
often alternate with each other within a little distance, 
and the character of the wine produced on them is remark- 
ably connected with the color of the earth. On the light- 
colored soils only a weak, white wine can be raised to ad- 
vantage, while on contiguous dark soils a strong claret of 
fine quality is made. (Gasparin, Cours @ Agriculture, 1, 
103.) 
Girardin found in a series of experiments on the cultiva- 
tion of potatoes, that the time of their ripening varied 
eight to fourteen days, according to the color of the soil. 
He found on August 25th, in a very dark humus soil, 
twenty-six var-eties ripe; in sandy soil, twenty; in clay, 
nineteen; and in white lime soil, only sixteen. It is not: 
difficult, however, to indicate other causes that will ace 
count in part for the results of Girardin, 
