Figure 1. (a) Two outer rows of corn stunted by influence of windbreak, Umatilla Experiment 



Farm, September 15, 1913. 

 (b) Stunted and irregular growth of peach trees caused by being too close to windbreak. 



The protection afforded by trees as windbreaks is more effective than 

 that of other forms of windbreaks owing to the greater height of the trees 

 and the greater space between the rows. Such windbreaks diminish evaporation 

 of moisture from soil and from crops. The benefit resulting from them depends 

 upon the extent to which they decrease wind velocity. The rate at which 

 moisture is carried away varies with rate of movement, temperature, and 

 humidity of the air. Warm, dry air in motion takes up much more moisture 

 than air which is quiet and cool. Evaporation of moisture from field crops 

 and orchard trees is greater than from the soil. With an increase in wind 

 velocity, the rate of loss increases faster from plants than from soils. 



These conditions must be met in the successful establishment of crops. 



