19171 FIELD CROPS. 31 



Alfalfa was given 6-, 9-, and 12-in. applications of water before ami at the 

 time the plants showed need of water by the dark green color of the foliage 

 and when the plants had suffered for water as indicated by the dark green 

 color of the foliage and drooping leaves. The results show that alfalfa can not 

 be allowed to reach the wilting stage without materially descreasing the yield 

 of hay. Where the plants were never allowed to show need of water the yield 

 was higher with a 6-in. than with a 9-in. application, but slightly lower than 

 with the 12-in. application. The greatest total yield was had at the expense 

 of yield per acre-foot of water and of quality of hay, the latter being due to 

 the large proportion of coarse stems to leaves. A gradual decrease in yield 

 was noted with the same applications of water applied as the wilting stage 

 advances. Alfalfa responded better than wheat, potatoes, and sugar beets to 

 heavy applications of water, but not so well as did clover the previous year. 



Potato yields were seriously affected by dry rot, but comparative results for 

 1914 and 1915 indicate that light applications of water are preferable under all 

 couditions. Very little difference in yield is shown, however, where the crop 

 receives four, six, or eight 3-iu. applications. Where the plants wilted before 

 irrigation a second growth was made, resulting in lowered starch content. 

 Plats receiving over 24 in. of water produced very scabby potatoes. 



The average results with sugar beets for 1914 and 1915 indicate that plants 

 irrigated after having wilted and failed to revive at night will not produce a 

 profitable crop. Only slight variations in yield were realized from 2-, 4-, and 

 6-in. applications, or from total applications of 12-, 18-, and 24-in., this being 

 partly attributed to the lateral diffusion of moisture from one plat to another. 

 The sugar content was not materially affected by the stage of wilting or 

 depth of application. The purity of the juice varied with the stage of wilting, 

 being greatest in beets which received 6-in. applications after the plants wilted 

 down and failed to revive at night. The beets in this plat produced 5.36 tons 

 per acre, while the highest-yielding plat produced 11.8 tons. 



The wheat experiments were altered in that 3-, 5-, and 7-in. applications were 

 made instead of 3-, 4.5-, and 6-in. applications, as previously, the stages of 

 growth remaining the same. The plats were harvested from August 9 to 17, 

 those receiving the least total irrigation, when an irrigation at the milk stage 

 was omitted, attaining maturity first. The three highest yields were obtained 

 from plats receiving four 7-in. applications, that on which the irrigation at 

 the 5-leaf stage was omitted, being first with 34.7 bu. per acre, with that on 

 which the irrigation at the boot stage was omitted second, and that on which 

 the irrigation at the dough stage was omitted third. With the omission of 

 irrigations at the 5-leaf and dough and the milk and dough stages, the yields 

 were 28.5 and 27.8 bu. per acre, respectively, and a marked decrease in yield 

 was noted on all other plats where two irrigations were omitted. With a 7-in. 

 application at each stage of growth a yield of 24.2 bu. per acre was obtained. 

 The yield obtained with four 7-in. applications when the irrigation at the milk 

 stage was omitted was 27 per cent less than the highest yield, 11 per cent less 

 than when the irrigation at the boot stage was omitted, 6 per cent less than 

 when the irrigation at the dough stage was omitted, and 8 per cent more than 

 when the irrigation at the bloom stage was omitted, thus indicating that the 

 bloom and milk .stages are critical periods in the irrigation of the wheat crop. 



With only two irrigations the yields were lower in all cases, but the 6-in. 

 application before heading and the 12-in. application after heading produced 

 the greatest yield, 27 bu. per acre. Nine- and 12-in. irrigations before heading 

 provided an excess of water over that utilized by the crop, as shown by de- 

 creased yields amounting to 39 and 40 per cent, respectively. 



