New YorK AGRICULTURAL EXPERIMENT STATION. 479 
lead to the conclusion that the 5.46 inches of rainfall left 
after the grass has taken its share of water and the natural 
waste has taken place, is not nearly enough to enable the apple 
to make an.optimum growth or produce an optimum crop. It 
should be noted, too, that grass makes its heaviest demands 
for moisture at the time when the trees need the water most. 
The conclusion that the differences in tree growth and crop 
in the two plants of this experiment are mainly due to differ- 
ences in moisture, are in accord with the teachings of the best 
authorities on soils in this country. Thus King states :1° 
“There are very few fields upon which crops of any kind, in 
any climate, can be brought to maturity with the maximum 
yields the soils are capable of producing without adopting 
means of saving the soil moisture.’ Hilgard'! holds that 
“under ordinary conditions of culture, and within limits vary- 
ing for different soils and crops, production is almost directly 
proportional to the water supply during the period of active 
vegetation.” Whitney” claims that the moisture supply in the 
soil is the only important factor to be regulated by the culti- 
vator in most soils, all other factors being, in general, pro- 
vided for naturally. A generation ago Johnson’® wrote: “ It 
is a well recognized fact that the next to temperature, the water 
supply is the most influential factor in the product of a crop. 
Poor soils give good crops in seasons of plentiful and well 
distributed rain or when skillfully irrigated, but insufficient 
moisture in the soil is an evil that no supplies of plant-food 
can neutralize.” | 
Table X shows that the average rainfall for the five years of 
this experiment is 2.11 inches more than the average for the 25 
years of which it isa part. Thus the period has been favorable 
for the sod-mulch method. 
* Physics of Agriculture. By F. H. King. Madison, Wisconsin: 1901, 
Pt Soil By E. W. Hilgard. New York: 1906, p. 193. 
2U. 8. Dept. Agr., Bureau of Soils, Bul. 22. 1903. 
78 How Crops Feed. By Samuel W. Johnson. New York: 1870, p. 216. 
