34 
BULLETIN 1388, U. S. DEPARTMENT OF AGRICULTURE 
season of the year and the maturity of the plant, it is difficult to dis- 
cuss water requirements of plants and their effect upon the choice 
of enterprises for an individual farm, except in the most general 
terms. Owing to the different conditions existing on farms, what 
might be good irrigation advice for one farm might prove to be un- 
wise for another. Each farmer therefore needs to study the water 
requirements for the different plants which are grown under the 
various soil conditions existing on his farm. 
Plants vary in their needs for water. Pastures and new seedings 
of alfalfa will require more moisture to maintain a successful growth 
than barley or wheat, for instance, which are grown under similar 
conditions. Good yields of wheat are produced on less water than 
is required by oats. 
WHEAT 
PREPARATION OF SOIL 
JAN. 
10 20 
FEB. 
10 20 
MAR. 
10 20 
APR. 
10 20 
MAY 
10 20 
JUNE 
10 20 
JULY 
10 20 
AUG. 
10 20 
SEPT. 
10 20 
OCT. 
10 20 
NOV. 
10 20 
DEC. 
10 20 
z^c 
' ' 
' ' 
' ' 
' ' 
' ' 
SEED _ _ 
— 
HARVEST 
THRESH FROM STACK 
SUGAR BEETS 
PREPARATION OF SOIL 
PLANT 
— 
POTATOES 
PLANT 
HARVEST 
ALFALFA 
RENOVATE £. CORRUGATE _ 
HARVEST (1) 

HARVEST (Z) 
HARVEST (3) 
CORN 
PR EPA RA TION OF SOIL _ 
PLANT _ 
— '• 
CULTIVATE 
HARVEST 
-~-^ 
FILL SILO 
SQUASH 
PREPARATION OF SOIL _ _ 
PLANT _ 
1 
CULTIVATE ETC 
HARVEST 
RUTABAGAS 
PLANT 
: __1 _. 

FALL PLOW 
ALFALFA 
NEW SEEDING 
FALL WHEAT 
SEED _ _ 
Fig. 9.— Usual range for the performance of principal field-crop operations in Yakima County 
The texture of the surface soil and subsoil and the topography of 
the land are important factors to be considered in applying water to 
crops. Sandy, shallow soils require light, frequent irrigations, whereas 
deep clayey soils can be irrigated less frequently with heavy applica- 
tions. Light frequent irrigations are needed on very sloping lands to 
prevent washing and give the soil an opportunity to absorb moisture. 
The season of the year and the maturity of the plant have much to 
do with the application of water. More water is needed during the 
hot summer and windy periods to overcome losses from evaporation. 
Plants which are sufficiently developed to shade the ground par- 
tially or completely are much easier to irrigate, because there is 
less baking and evaporation. 
