ANNUAL REPORT, 1938 19 



The Effect of Time of Cutting on Yields of Alfalfa and the Use of Potash in 

 Preventing Winterkilling of Alfalfa. (Karol J. Kucinski, Walter S. Eisenmenger 

 and Ralph W. Donaldson.) This experiment has been continued for the past 

 three years. Mowings of alfalfa were made at definitely spaced intervals of time 

 to determine the best management practice for alfalfa growing. Some plots were 

 cut three times and others were cut twice per season, beginning in early June and 

 extending to late September. This year, as in the past two, the higher yields 

 were obtained on those plots having a schedule of three cuttings, although the dif- 

 ference in yields between the plots cut three times and those that were cut twice 

 was not as great as in the past two years. The stand of alfalfa in the fall where 

 two cuttings were made was generally superior to that where three cuttings 

 were made. Portions of each plot, which did not receive anj' potash, did not 

 withstand the elements of winter and nearly all of the alfalfa has been winter- 

 killed and replaced by a thick stand of volunteer grass and weeds. 



Alfalfa Variety Tests. (Walter S. Eisenmenger and Karol J. Kucinski.) In 

 cooperation with the U. S. D. A., 15 strains of alfalfa seeded in 1935 have been 

 continued as a basis for yield and longevity studies. The Grimm variety was 

 used as standard check. 



The longevity of the varieties, based on observation made in the spring, may 

 be tentatively rated as follows: 



Better than Same as Poorer than Least 



Grimm (Check) Grimm Grimm Adapted 



Hardigan Ont. Variegated Arizona Common Argentina 



Hungarian Dakota Common Utah Common Hardistan 



Italian Cossack Kansas Common Ladak 



New Mexico Turkistan 



Effect on pH from Adding Sulfur to a Soil. (Ralph W. Donaldson, W. G. 

 Colby, and Hrant M. Yegian.) Ordinary finely ground sulfur was applied in 

 100, 250, 500, and 1,000 pound rates per acre to a soil of very fine sandy loam 

 texture with initial pH of 6.5. The effect on soil pH was observed during an 

 87-day period (March 16-June 11, 1938) in triplicate pot trials under greenhouse 

 conditions of temperature and reasonably high moisture. Readings started 10 

 days after the sulfur was applied, and were recorded at weekly intervals, using 

 a Beckman glass electrode potentiometer. 



Definite change in reaction was already apparent in 10 days and was virtually 

 complete by the end of 30 days. Additions of sulfur to this soil tended to lower 

 the pH in fairly direct proportion to the amount of sulfur applied. The decrease 

 per unit of applied sulfur was smaller, however, as larger applications were made. 

 The amount of pH change effected by each increment of sulfur, compared with 

 that of the untreated soil, is shown as the average difference for all readings, 

 as follows: 



Rate of Sulfur Average Reduction in 



Application pH Readings for the Period 



March 26-June 11 



100 pounds 169 



250 pounds 386 



500 pounds - 689 



1,000 pounds 1 . 159 



Potato Variety Trials. (Ralph W. Donaldson, Walter S. Eisenmenger, and 

 Karol Kucinski.) Trials of 8 varieties were made at the college. Two of the 

 newer varieties, Houma and Warba, yielded well. Chippewa, which in other 



