16 BULLETIN 618, U. S. DEPARTMENT OF AGRICULTURE. 



Fargo, N. Dak. The evaporation, however, is much higher at Ama- 

 rillo than at these stations in the northern part of the subhumid 

 division of the Great Plains area. 



Results Obtained. 



The results of varietal experiments with durum wheat at 30 

 different experiment stations are presented herein. At most of these 

 stations the experiments have been conducted by the Office of 

 Cereal Investigations, either cooperatively with the State experi- 

 ment station or some other agency or independently. At the remain- 

 ing stations the data have been obtained independently by the 

 State or Province. The source of the data is stated in connection 

 with each station. 



The experimental conditions, such as crop sequence, size of plat, 

 width of alleys, number of replications, etc., vary somewhat at 

 different stations. The results obtained at one station, therefore, 

 are not necessarily comparable with those obtained at any other 

 station. In most cases, however, they probably are directly com- 

 parable. The results from different varieties at the same station 

 were nearly always obtained under similar conditions and may be 

 compared directly. Any known exceptions to this fact are stated 

 in the text. In all cases the crops are grown with only the natural 

 rainfall and under conditions approximating good farm practice 

 for the district. 



The value to crops of any given rainfall depends on the time and 

 nature of its occurrence, on the kind of soil, and on the quantity 

 and nature of the wind, as well as on other factors. Not one factor, 

 but the total influence of all factors, must govern the classification 

 of land for agricultural purposes. 



The results from the durum varieties under experiment are shown 

 for each station. Usually all varieties that have been grown for 

 more than one or two years are included. In the tables they are 

 separated into the major groups given in the key to groups and 

 varieties. 



The yields of the durum wheats are compared with those of the 

 standard common wheats at each station. The highest yielding 

 variety in each important group of common wheat is chosen for 

 this comparison. Occasionally two varieties are given in one group, 

 as in the Fife group, where such old standard varieties as Power, 

 Glyndon, and Rysting are now being outyielded by Marquis. 



In figures 8, 12, and 13, the vertical column showing the yield of 

 durum wheat is based on the yield of only the highest yielding 

 variety in the period of years indicated, except when otherwise 

 noted. 



