| OCR Text |
Show Bulletin No. 173 favorable amount of water for potatoes seems to be between 30 and 40 inches. For applications above 60 inches the yield drops very rapidly- much more so than with sugar- beets. This is probably due in part at least to the fact that excessive water prevents the tubers from securing the supply of air that is so necessary to their best growth. Table III. Yield of Potatoes with Various Quantities of Irrigation Water. Total of 216 Trials extending through 1U Years. Acre- inches Number of Number of Yield in Bushels Water Trials Years per Acre None 12 12 117.37 2% 4 4 157.19 5 39 14 162.23 7% 20 9 165.38 10 39 14 217.24 12% 4 4 284.87 15 39 14 228.62 17% 1 1 293.75 20 13 13 266.53 22% 2 2 321.18 25 4 4 204.02 27% 2 2 345.5 30 7 7 269.92 32 y2 4 4 377.59 40 2 2 341.44 45 8 8 271.39 50 1 1 83.45 55 3 3 240.00 60 6 6 304.00 65 1 1 246.00 67% 1 1 246.00 75 1 1 74.22 82% 2 2 149.00 97% 1 1 85.00 RESULTS WITH ALFALFA Experiments on the irrigation of alfalfa extended over 14 years with a total of i76 trials. The results are given in Table IV and Figure 5. An examination of the results for alfalfa shows that this crop can profitably use much larger quantities of water than any of the other crops under investigation. The highest yield was secured with 50 acre- inches. This treatment averaged nearly & V2 tons to the acre during 8 years. There was a decline in yield when quantities of water larger than this were used, but th ® decline was slow. Alfalfa is seen to be much less sensitive to over- irrigation than potatoes and sugar- beets. Although the |
