ANNUAL REPORT. 1040 17 



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

 and Karol J. Kucinski.) Based on yields, the ranking of potato varieties 

 grown in plots at the college during the season of 1940 was Houma, 

 Sequoia, Green Mountain, Sebago, Russet Rural, Earlaine No. 2, Chip- 

 pewa, Irish Cobbler, Warba, Katahdin, and Mesaba. The average yield 

 of all varieties mentioned was 50 percent more on plots sprayed twelve 

 times than on plots sprayed only twice. 



Downward Movement of Lime in Pasture Soils. (Arthur B. Beaumont.) 

 In the spring of 1924 lime was applied as topdressing in two rates to 

 certain plots used in a pasture experiment. In the fall of 1940, 16>4 

 years later, samples of soil from these plots were tested for reaction. The 

 results are as follows: 



The Effect of Fineness of Limestone on Soil Reaction. ( Ralph W. 

 Donaldson, Walter S. Eisenmenger, and Hrant M. Yegian.) How soon 

 does liming become effective in sweetening soil and how do commercial 

 lime products of varying fineness compare in this respect? These points 

 are frequently raised by farmers and by lime manufacturers. 



A preliminary study has been in progress eight months to observe what 

 changes in pH are produced under a laboratory setup where commercial 

 limes of differing fineness are applied to soil and results measured at 

 frequent intervals by means of a Beckman glass electrode meter. Both 

 limed and unlimed samples were kept in glass jars and maintained at 

 optimum moisture conditions, with no plants being grown. 



Five commercial grades of limestone, ranging from coarsely ground 

 (509f through 60-mesh) to moderately finely pulverized (95% through 

 60-mesh), and one hydrated lime were thoroughly mixed with dry soil to 

 furnish equivalent oxides and applied in three different rates — 1^, 3, and 

 6 tons of (equivalent) limestone to the acre. These limes were compared 

 on two Becket loams; one of initial pH 5.4 and the other a forest podzol 

 of pH 3.6. Results obtained so far indicate: 



1. With one soil (podzol), the sweetening effect of each lime was im- 

 mediate and greatest at the first 10-day period of sampling. This condition 

 remained fairly constant for about three months, after which differences 

 between limed samples and the unlimed check decreased considerably. 



With the other (less acid) soil, the initial change in pH induced by 

 liming was also great; but after two months, in contrast with the other 

 soil, differences between limed samples and the unlimed check tended in 

 some cases to increase. 



2. The finest lime (hydrated) produced the greatest change and the 

 coarsest grade of limestone produced the least change in soil reaction. 

 This distinction was measurable and consistent for these materials applied 

 at all three rates and on both soils. 



