is any particular connection between the growing of wheat seedlings
in small pots or bottles for a few twenty-day periods and the
growing of crops in soils during successive seasons. No, I don't
take any stock in their theories. I think they are _watered, _or
perhaps I should say _hydrated, _in deference to science. But I
would like to know about this question of plant food coming up from
below. That would be a happy solution of the fertilizer problem."

"It is true," said Percy, "that soluble salts are brought to the
surface in the rise of moisture by capillarity in times of partial
drouth; and in the arid regions where the small amount of water that
falls in rain or snow leaves the soil only by evaporation, because
there is never enough to produce underdrainage, the salts tend to
accumulate at the surface. The alkali conditions in the arid or
semiarid regions of the West are thus produced. But in humid
sections where more or less of the rainfall leaves the soil as
underdrainage the regular loss by leaching is so much in excess of
the rise by capillarity that soils which are not affected by erosion
or overflow steadily decrease in fertility even under natural
conditions, with no cultivation and no removal of crops. Of course
this applies at first only to the mineral plant foods, as phosphorus
potassium, magnesium, and calcium. While mineral supplies are
abundant in the surface soil, there may be a large acumulation of
organic matter and nitrogen, especially because of the growth of
wild legumes, which are very numerous and in places very abundant,
especially on some of the virgin prairies of the West. However, as
the process of leaching proceeds there comes a time when the growth
of the native vegetation is limited because of a deficiency in some
essential mineral plant food, such as phosphorus, or the limestone
completely disappears and soil acidity develops which greatly