SPRING WHEAT IN THE GREAT PLAINS AEEA. 



Or a succession of years may be either comparatively wet or com- 

 paratively dry. 



The seasons of light rainfall are usually accompanied by other un- 

 favorable conditions, such as higher wind velocity, higher tempera- 

 ture, and lower humidity. The distribution of the rainfall is also very 

 important in its influence on crop production. A crop may be pro- 

 duced on a relatively small seasonal rainfall if it is well distributed. 

 On the other hand, a season of higher rainfall, because of unfavorable 

 distribution, may result in crop failure. 



Space in this bulletin will not permit the presentation of a com- 

 plete record of the climatic conditions at the various stations during 

 the time the work here reported was being done. It is, however, 

 available in publications of the United States Weather Bureau. 

 Table I gives the lowest, highest, and average annual and seasonal 

 precipitation for the time covered by the work. The seasonal evap- 

 oration is also shown. By seasonal is meant the precipitation or 

 evaporation for the period between the average time of seeding and 

 the average time of harvesting. No attempt is made to show other 

 climatic factors, all of which are important. 



Table I.- 



-Annual and seasonal -precipitation and seasonal evaporation at fourteen 

 stations in the Great Plains area. 1 



Station. 



Alti- 

 tude 2 

 (feet). 



Precipitation 3 (inches). 



Annual. 



Mini- 

 mum. 



Maxi- 

 mum. 



Aver- 



Seasonal. 



Mini- 

 mum. 



Maxi- 

 mum. 



Aver- 



Seasonal evaporation ; 

 (inches). 



Mini- 



Maxi- 



mum. 



mum. 



19.117 



26. 273 



19. 820 



20. 594 



21. 104 



28. 269 



18.379 



27. 366 



17.664 



25.362 



20. Ill 



24.248 



23.627 



33.906 



24.698 



26.647 



25. 954 



35. 255 



25. 917 



32. 691 



29.390 



41.317 



33.315 



38.926 



33. 381 



41.002 



32. 305 



40. 704 



Aver- 

 age. 



Judith Basin. 



Huntley 



Willis ton 



Dickinson 



Edgeley 



Hettinger 



Belle Fourche 

 Scottsblufl... 

 North Platte. 



Akron 



Hays 



Garden City.. 



Dalhart 



Amarillo 



4,228 

 3,000 

 1,875 

 2,543 

 1,468 

 2,253 

 2,950 

 3,950 

 3,000 

 4,600 

 2,050 

 2,900 

 4,000 

 3,676 



14.96 

 11.92 

 10.28 

 11.93 

 11.94 

 12.72 

 6.64 

 13.77 

 11.18 

 14.51 

 15.59 

 11.82 

 13.69 

 10.69 



23.78 

 11.92 

 18.99 

 21.22 

 21.95 

 15.68 

 17.73 

 18.51 

 23.01 

 22.46 

 27.80 

 23.58 

 16.35 

 27.80 



18.06 

 11.92 

 14.84 

 16.69 

 16.71 

 14.20 

 13.11 

 16.14 

 18.05 

 18.28 

 21.30 

 18.54 

 15.11 

 18.28 



6.50 

 5.00 

 5.62 

 5.31 

 5.08 

 8.82 

 1.92 

 5.56 

 4.38 

 5.32 

 3.87 

 5.01 

 4.54 

 5.03 



10.90 



7.35 

 12.00 

 16.27 

 15. 73 

 12.89 

 12.75 



8.26 

 11.25 



9.52 

 12.87 



8.16 

 14.86 

 11.49 



8.62 

 6.18 

 8.31 



10.06 

 9.60 



10.69 

 6.82 

 7.11 

 7.77 

 7.82 

 9.55 

 6.85 

 8.17 

 7.05 



21.330 

 20. 207 

 24.705 

 22.377 

 20.657 

 22. 430 

 27. 220 

 25. 718 

 30. 253 

 28. 781 

 32. 628 

 35. 332 

 38.596 

 36.709 



1 The years covered are the same as for the data shown in the other tables for each station. 



2 The altitude given is for the field where the work was done and is based in most cases on that of the 

 nearest town. 



3 The record of annual precipitation for 1914 is not included. The records of seasonal precipitation and 

 evaporation for 1914 are included for all stations, the evaporation being figured from Apr. 1 to July 31. 

 The seasonal rainfall is the amount from Apr. 1 to July 31 for stations north of and including that at Belle 

 Fourche. For stations south of Belle Fourche it is the amount between Mar. 1 and June 30. Evaporation 

 measurements are made from a free water surface in a tank sunk into the soil to almost its full depth. The 

 water surface is kept about level with the surface of the ground. 



GENERAL PLAN OF THE INVESTIGATIONS. 



Durum wheat has been used in these trials. The aim has been to 

 use at each station the best standard variety available for general use. 

 Changes are made only when necessitated by loss of seed or when 



