1917 J FIELD CROPS. 35 



An Irrigation experiment with clover, sugar beets, potatoes, and wheat, 

 C. S. Knight {Nevada Sta. Rpt. 1915, pp. 2^-28). — This experiment was con- 

 ducted in 1914 on soil varying from a sandy loam to a clay loam. In the irri- 

 gation, of clover 6, 9, and 12 inch applications were made at various stages of 

 wilting. The results showed that clover can not be allowed to reach the wilt- 

 ing stages without materially decreasing the yield of hay, and that on soils 

 such as that of the experiment applications of from 9 to 12 in. given before the 

 plants show need of water are essential for the heaviest production. 



Potatoes were given 3, 6, and 9 inch applications of water before and at the 

 time the plants showed a tendency to wilt, when all leaves wilted down once, 

 and when all plants failed to revive at night. Where the plants were allowed 

 to wilt to the extent where they failed to revive at night it was found impos- 

 sible to produce a satisfactory crop. The highest yields were produced with 

 the smallest application of water, although little difference was shown in yield 

 where the crop received two, four, or five 3-inch applications. The highest 

 starch content was secured with the smallest applications when the plants were 

 never allowed to wilt, and in the three stages of wilting the highest starch 

 content was obtained with the largest applications. 



An experiment similar to the one with potatoes was conducted with sugar 

 beets with the exception that 2, 4, and 6 inch applications of water were made. 

 Where no irrigation was given until the plants wilted down and failed to re- 

 vive at night, an unsatisfactory crop was produced. With 2-inch applications 

 the beets in all stages of wilting showed a higher sugar content than those re- 

 ceiving the greater amounts of water. The purity of the sugar was greatest in 

 the beets irrigated only after all plants had wilted down once. 



Wheat was given 3, 4^, and 6-inch applications of irrigation water at the 

 five-leaf, boot, bloom, milk, and dough stages. A comparison was made of 

 plants receiving an irrigation at each of the five stages, with plants in which 

 an irrigation was omitted in each of the five stages, with plants in which 

 irrigation was omitted at any two of the five stages, and with those that 

 received the same amount of water in only two applications — one before and 

 one after heading. Where one irrigation was omitted, the omission of the 

 application at the five-leaf stage gave the best results, with a difference in 

 yield of less than 3 per cent in the three highest producers. Where two irriga- 

 tions were omitted satisfactory results were noted only where the irrigations 

 were omitted at the five-leaf and dough stages. Four 6-inch irrigations with 

 one application omitted at the five-leaf stage yielded 25.8 per cent more than 

 five 6-inch applications. Omission of irrigations between the boot and milk 

 stages greatly decreased the yield of grain. With only two irrigations the 6- 

 and 12-inch applications proved most satisfactory. Of the results in yield 

 83 per cent were in favor of the 6-inch applications, the difference being 

 greatest where two irrigations were omitted at the five-leaf and dough stages. 



The different depths affected the soil moisture only to a slight extent when 

 two irrigations were omitted, but when only one irrigation was passed over 

 an average difference of 12.3 per cent was noted in the first 3 ft. in favor of 

 the 6-inch application. In the first 2 ft. with 6-inch applications the average 

 soil moisture content before irrigation at the milk stage was 20 per cent less 

 where two irrigations were omitted than where only one irrigation was omitted. 



The average nitrogen content of the plants for all plats at the different 

 stages of growth is given as follows : Five-leaf 4.37 per cent, boot 2.75 per cent, 

 bloom 2.09 per cent, milk 1.4 per cent, and dough 1.25 per cent. 



