400 



FORESTRY AND IRRIGATION 



made this year are Nebraska. Colorado, 

 Oklahoma, and Kansas. * The fifth will 

 be either Minnesota, North Dakota, or 

 Iowa. Ultimately the investigations 

 will cover Minnesota, North Dakota, 

 Si aith Dakota, Nebraska, Iowa, Kan- 

 sas. Oklahoma, Colorado, Texas, New 

 Mexico, Utah, California, Washington, 

 and Idaho. 



The sudden ruin that hot winds 

 sometimes bring to growing crops in 

 parts of the West is well known. 

 Blowing strongly across the unobstruct- 

 ed plains, these winds may in a few 

 days blast all hope of even a partial 

 harvest. This is particularly true in the 

 lower portion of the central plains re- 

 gion, and in years of unusually low 

 rainfall. Here the winds most to be 

 feared blow from the southwest or 

 smith. In the northern prairie region 

 the former is exposed to the hot "Chi- 

 nook" wind, which sweeps down from 

 the Canadian mountains. This either 

 dries out growing crops, or, if it pre- 

 vails before the danger of killing frosts 

 is past, causes loss through urging 

 vegetation forward prematurely. Cold 

 winter winds also do great injury to 

 crops, make the climate more severe for 

 stock and men, and interfere with an 

 even covering of snow upon the ground. 

 This is true from Canada almost to the 

 Gulf. 



In Southern California, dry winds 

 from the north and northeast sweep 

 down from the Mohave Desert with de- 

 structive results. Coming in June, these 

 winds may reduce the wheat yield of 

 unprotected fields to almost nothing. 

 Windbreaks of eucalyptus and Monte- 

 rev cypress, now in such common use to 

 protect orange groves and orchards, 

 long ago convinced possessors of high- 

 ly valuable irrigated land of the value 

 of tree planting for protection purposes. 



But there are two sides to the wind- 

 break question. Some prairie farmers 

 declare positively that belts of osage 

 orange, for instance, are a "nuisance." 

 Others cite figures to show positive 

 benefit. Mr. Morris Thompson who 

 lives near Downs, Kans., gives his yield 

 of corn from a field protected on the 

 south by a row of tall cottonwoods as 



six bushels per acre more than in 

 places where there is no protection. 

 About fifteen acres are benefited in this 

 way. It is highly improbable that the 

 windbreak occupies sufficient land to 

 offset this benefit. 



An Illinois farmer sums up his ob- 

 servations upon this matter thus: "M\ 

 experience is that now. in cold and 

 stormy winters, wheat protected by tim- 

 berbelts yields full crops, while fields 

 not protected yield only one-third of a 

 crop. Twenty-live or thirty years ago 

 we never had any wheat killed by win- 

 ter frosts, and every year a full crop of 

 peaches, which is now rare. At that 

 time we had plenty of timber around 

 our fields and orchards, now cleared 

 away." 



The Forest Service proposes to find 

 out just when and how much wind- 

 breaks increase the yield of crops. To 

 carry out the plans, much technical 

 work will be necessary. Instruments 

 will be used to measure heat and cold, 

 moisture and dry ness, both above and 

 below ground ; to register the force of 

 the wind near the windbreaks, and 

 some distance away ; to measure light 

 intensity, and take note of the effects of 

 shade ; to register frost at different dis- 

 tances from the trees ; and to keep ac- 

 count of the effect of the windbreaks 

 on the MIOW which covers the ground 

 to leeward in winter. Many other 

 measurements and tests will be made, 

 and elaborate data will be collected by 

 experts who will have charge of the 

 study. 



Many disputed questions \vill thus be 

 settled and the data gathered will be 

 placed at the disposal of the farmers 

 who desire it. Doubtless rows of trees 

 between fields sometimes do more harm 

 than good, by casting shade and ab- 

 stracting water from the soil. Trees 

 may also increase the danger from 

 frost, since the movement of the air 

 lessens that danger. The Forest Serv- 

 ice will study all sorts of conditions, in- 

 cluding the relative value of wind- 

 breaks, consisting of a single row of 

 trees, and shelterbelts, made up of a 

 number of such rows. A windbreak 

 is usually planted for protection alone. 



