10 



FARMERS BULLETIN 788. 



from the windbreak increased. The total gain was about equal to 

 the amount of grain which could have been grown on the shaded 

 ground near the trees. The season in which the measurements were 

 taken was not of high winds, nor did it lack moisture. It would 

 appear, therefore, that in a windy year when evaporation was high 

 the total gain for the field would much more than balance the loss. 

 In another case, barley on the south of an ash and honey locust wind- 

 break benefited very materially from the accumulation of snow in the 

 lee, and the conservation of this moisture. Here cultivation was pos- 

 sible within 4 feet of the stems of the trees, so that the increased 



FIG. 7. Effect of favorable atmospheric conditions on growth of corn plants and yield of 

 fodder. On right, in protected zone (weight, 81 pounds) ; on left, in unprotected 

 zone (weight, 42 pounds). 



yield of the field, amounting to about 14 bushels per acre at the 

 highest point, was practically clear gain. The total gain for the 

 whole field amounted to the yield of a strip of ground as long as the 

 .windbreak, and three times as wide as its height. In other words, 

 had the windbreak, which was 20 feet high, occupied a strip of 

 ground 60 feet wide, the gain in the field crop would have paid the 

 rental on all of this ground. 



The corn crops showed more consistent and marked benefits from 

 protection than any others. In the region concerned the summer 

 winds are almost wholly from the south, so that the only effective 



