338 FOE AGE PLANTS AND THEIR CULTURE 



watch carefully the condition of the plants. When the 

 water supply becomes too low, the growth is checked and 

 the leaves become darker and duller in color than those 

 of vigorously growing plants. The wilting of the leaves 

 is also indicative of insufficient moisture, especially if it 

 occur before or after the heat of midday. Fortier also 

 recommends that the soil at a depth of about 6 inches be 

 examined. If it will readily form a ball when pressed 

 between the hands and retain its form, there is sufficient 

 moisture present ; but if the ball falls apart when the 

 pressure is removed, irrigation is needed. 



The number of irrigations a year when water is avail- 

 able varies from 4 in Montana to as many as 12 in Ari- 

 zona and California. The number depends upon various 

 factors, especially the depth and character of the soil, 

 the depth of the water table, number of cuttings and such 

 climatic factors as temperature, rainfall, humidity and 

 wind movements. 



In localities where water is abundant only in the spring 

 and early summer, it is the common practice to water 

 more freely and more frequently at that time, as 

 this tends to lessen the amount needed later in the 

 summer. 



402. Winter irrigation. In parts of the West, where 

 the water supply happens to be abundant in winter and 

 scant or even lacking in summer, fields are irrigated in 

 winter when the plants are dormant. This is especially 

 practical in regions where the winters are mild. The prin- 

 cipal object is to conserve water which would otherwise 

 be wasted, the soil retaining a large amount and thus 

 lessening the water required during the summer. Even 

 where no water is available in summer, one good cutting 

 is in many places obtained as the result of winter irriga- 



