LOSS OF RAINFALL 97 
spring wheat were placed in the moist surface soil, 
and 1 inch of dry soil added to the surface to pre- 
vent evaporation. No more water was added; the 
air of the greenhouse was kept as dry as possible. 
The wheat developed normally. The first ear was 
ripe in 132 days after planting and the last in 143 
days. The three cylinders of soil from semiarid 
western Nebraska produced 37.8 grams of straw 
and 29 ears, containing 415 kernels weighing 11.188 
grams. The three cylinders of soil from humid 
eastern Nebraska produced only 11.2 grams of straw 
and 18 ears containing 114 kernels, weighing 3 
grams. This experiment shows conclusively that 
rains are not needed during the growing season, if 
the soil is well filled with moisture at seedtime, 
to bring crops to maturity. 
What becomes of the rainfall ? 
The water that falls on the land is disposed of in 
three ways: First, under ordinary conditions, a 
large portion runs off without entering the soil; 
secondly, a portion enters the soil, but remains near 
the surface, and is rapidly evaporated back into the 
air; and, thirdly, a portion enters the lower soil 
layers, from which it is removed at later periods by 
several distinct processes. The run-off is usually 
large and is a serious loss, especially in dry-farming 
regions, where the absence of luxuriant vegetation, 
H 
