294 MISCELLANEOUS FARM SUBJECTS 



eight months, at the end of a season during which many orchards 

 died, no thriftier or more vigorous orchard existed in the valley. 



These results may be explained as follows: During the winter 

 the lower temperatures and the higher relative humidity cause evap- 

 oration to be much slower than during the remainder of the year. 

 In applying water, therefore, comparatively little escapes into the 

 atmosphere. The supply of water being greatest at that time of the 

 year makes it possible to apply large amounts at short intervals, thus 

 avoiding the loss that occurs if small amounts are applied at greater 

 intervals. Then, too, the trees are dormant and the roots need little 

 air; hence, no injury is done them by keeping the soil supermois- 

 tened, or by letting the surface bake to some extent. Consequently, 

 cultivation after each irrigation is not necessary, much time thus 

 being saved. 



During the summer the climatic conditions and the demands 

 of the trees are quite the reverse of those of the winter. The high 

 temperatures and the low relative humidity cause such rapid evap- 

 oration that much of the water applied quickly escapes into the 

 atmosphere. The supply of water for irrigation being very low, it 

 is not ordinarily possible to apply sufficient quantities of water to 

 reach the deeply-seated roots of the tree. In summer a large per- 

 centage of the water applied escapes directly from the soil without 

 passing through the trees. This is the case whether its surface is 

 cultivated (as should be done) and the upper few inches loses all 

 its moisture as a result; or the soil is left to bake (as should not be 

 done) and not only the surface becomes dry and hard, but a large 

 amount passes up from below through the baked soil. 



If about the middle of the summer, water is available in abun- 

 dance, it would probably be wise to give the orchard a thorough 

 irrigation in as short a time as possible, and then follow the irriga- 

 tion with a thorough plowing, as in the spring after the winter- 

 irrigation ceases. But frequent summer irrigations are decidedly 

 not advisable where the soil is fairly deep and retentive of moisture. 



Irrigation Crops. Tree planting should be one of the first 

 things undertaken by the plains farmer, so that windbreaks may be 

 established as soon as possible. (B. P. I. Bui. 83.) 



Alfalfa. Alfalfa is most commonly irrigated by being flooded 

 from field laterals. It is a tender plant for the first few months of 

 its growth and requires favorable conditions. The feeding value of 

 alfalfa is so high that the greatest profits can be obtained usually by 

 feeding it to farm animals. When sold in the stack the net profits 

 vary between somewhat wide limits. From the three tabulated 

 statements which follow some idea may be given of the profits to the 

 grower under skillful practice: 



Profits from Alfalfa Growing. 



Yakima Valley, Wash.: 



Annual cost of water per acre $ 1.50 



Cleaning and repairing farm ditches 50 



Annual taxes 75 



Cost of applying water during the season 3.50 



