206 Alaskan Science Conference 



Soil Climate of the Region 



The greater part of the land of the Tanana valley lies on the 

 permanently frozen ground— permafrost. This is a very signifi- 

 cant environmental factor for agricultural land use. It has a 

 profound effect on the soil climate, soil temperature and soil 

 moisture as well as upon the soil type and microflora. Our 

 information about these facts is scarce and fragmentary. 



Our observations and experiments were limited chiefly to 

 soil temperature and pedothermal deficiency. During the sea- 

 son we recorded soil temperature variations at various positions 



Table 5.— Soil temperature profiles at the depth of 6 and 12 inches, May-August 



1949, degree days above ^i°F. 



A. On the Hillside Field— Elevation 510 feet (College, Alaska). 



(Degree days in degrees of Fahrenheit) 



May 25-31 June J U1 Y August Total 



Depth 6" 12 174 415 385 986 



Depth 12" — 1.4 148 379 330 867 



i8 53 °F. 



B, On the Bottomland— Elevation 475 feet (College, Alaska). 



Depth 6" — 0.9 19 283 264 561 



Depth 12" —9.5 —123.5 !4 -5 "37 l U 



7 o 5 °F. 



in the hillside field and bottomland of the Station. The hillside 

 field was cleared in 1907 and the permafrost table is at 40 feet, 

 as has been found by digging a well, while on the bottomland, 

 which was cleared 15 years ago, the permafrost table is lowered 

 only to 15 feet. Soil temperature in both fields during the sea- 

 son is quite different as shown on Table 5. Soil temperature 

 on the bottomland, particularly at the depth of 12 inches, is 

 considerably lower than on the hillside field, the total difference 

 being only 38% of the hillside temperatures. A temperature of 

 50 °F. was reached at the depth of 6 inches on the hillside July 3 

 and on the bottomland July 9, while at the depth of 12 inches 

 on the bottomland the highest was 48 °F. reached July 24. 

 These temperatures are evidently correlated with the mois- 



