60 



BULLETIN 1026, U. S. DEPARTMENT OF AGRICULTURE. 



Table 16. 



-Summary of records of the irrigation of crops in the Cache La 

 Poudre Valley in 1916 and 1917. 



Crop. 



Num- 

 ber of 

 fields. 



Total 

 area of 

 fields 

 (acres). 



Number of irrigations. 



Size of head used 

 (second-feet). 



Ratio of hours attended 

 to hours run. 



Aver- 

 age. 



Maxi- 

 mum.. 



Mini- 

 mum.. 



Aver- 

 age. 



Maxi- 

 mum. 



Mini- 

 mum.. 



Aver- 

 age. 



Maxi- 

 mum. 



Mini- 

 mum. 



Alfalfa 



Wheat 



Oats 



Barley 



Sugar beets. 



Potatoes 



Beans 



74 

 26 

 15 

 31 

 61 

 38 

 18 



1,674 

 491 

 196 

 364 

 960 

 442 

 225 



3.02 

 1.21 

 1.64 

 1.27 

 2.90 

 3.79 

 2.69 



7 

 2 

 4 

 3 

 5 

 6 

 5 



2 

 2 



2.59 

 2.23 

 2.25 

 2.10 

 1.85 

 1.99 

 2.02 



7.78 

 4.59 

 5.20 

 5.22 

 4.47 

 3.70 

 3.17 



0.58 

 1.16 

 1.21 

 .99 

 .52 

 .55 

 1.21 



0.57 

 .56 

 .02 

 .62 

 ,71 

 .68 

 .80 



1.00 

 .88 

 1.00 

 1.00 

 1.00 

 1.00 

 1.00 



0.04 

 .22 

 .33 

 .16 

 .46 

 .40 

 .55 



Crop. 



Number of acres irri- 

 gated per day. 



Depth of water applied 

 (feet). 



Average yield 



Aver- 

 age. 



Maxi- 

 mum. 



Mini- 

 mum. 



Aver- 

 age. 



Maxi- 

 mum. 



Mini- 

 mum. 



per acre. 



Alfalfa 



6.02 

 5.13 

 5.43 

 4.45 

 5. 70 

 6.78 

 15.63 



19.52 

 17.54 

 12.02 

 31.04 

 24.72 

 22.27 

 54.80 



1.55 

 2.22 

 1.61 

 1.39 

 1.75 

 1.51 

 6.72 



2.57 

 1.04 

 1.35 

 1.19 

 1.86 

 2.20 

 .69 



13.59 

 2.81 

 3.07 

 3.98 

 6.59 



16.94 

 1.06 



0.52 

 .17 

 .60 

 .14 

 .32 

 .74 

 .34 





Wheat 



27. 75 bushels. 



Oats 



48. 06 bushels. 



Barley 



40. 73 bushels 





12. 56 tons. 



Potatoes 



230 07 bushels 



Beans 



22. 75 bushels. 







Table 17. — Average dates of irrigation. 



Crop. 



First. 



Second. 



Third. 



Fourth. 



Fifth. 



Sixth. 



Alfalfa 



May 25 

 June 16 

 July 19 

 July 30 

 June 24 



July 8 

 June 25 

 Aug. 14 

 Aug. 15 

 July 27 



Aug. 3 

 July 9 

 Aug. 31 

 Aug. 18 

 July 24 



Aug. 17 



Aug. 8 





Grain . . 







Sept. 5 

 Aug. 21 

 Aug. 14 



Sept. 2 

 Aug. 24 





Potatoes ... 



Sept. 8 









1 



In figures 5 to 8 the distribution of the demand throughout the 

 season is shown for the acreage in the principal crops on the farms 

 selected for the investigation of farm irrigation. Figure 9 shows 

 the combined demand of all tlie crops on these farms each year. 



It will be noticed by reference to figure 1 that 5 inches, or more 

 than one-third of the average annual rainfall, occurs in April and 

 May. For this reason it usually happens that the crops have a 

 natural start and are growing vigorously before any irrigation is 

 necessary. When it becomes necessary to irrigate to bring up the 

 crops, poor returns are expected. 



The curves shown in figures 10, 11, 12, and 13 show for the four 

 principal crops the relation between the depth of water applied 

 and the yield obtained. The yield per acre for each field shown in 

 Tables 17 and 18 was plotted against the corresponding depth of 



