Agro-Climatological Investigations— Bensin 211 



features to be considered. The presence of high hills or air 

 drainage around the fields has a profound effect upon crop 

 growth during the growing season and particularly on air tem- 

 perature. Temperature records made during the month of 

 July 1949 on our 3 stations at different elevations of 620, 510 

 and 475 feet indicate the highest temperature on the southern 

 slope at 510 feet during the day, as is shown on Fig. 7. During 

 the night higher temperature was noted on the top of the hill, 

 elevation 620 feet, while the bottomland temperature recorded 

 was higher than on the hillside. This is probably due to night 

 radiation of dark colored soil of the bottomland field. 



The southern slope of the land is the warmest spot, and 

 should be used for agriculture with considerable advantage. 

 On uncleared land natural vegetation of the southern slopes 

 is conspicuously different from vegetation of northern slopes, 

 in this region. Aspen trees (Populus tremuloides) and high 

 bush cranberry (Viburnum pauciflorum) can be considered as 

 indicators of the warmer land of the southern slopes, where the 

 permafrost table is low and the peat moss (Sphagnum sp.) 

 associated with a high permafrost table is absent. 



We can create favorable microclimatological conditions on 

 the limited areas of land used for agriculture. Several experi- 

 ments in this direction were originated and conducted by the 

 author at the Alaska Agricultural Experiment Station. The 

 main object of these experiments was to overcome thermal and 

 pedothermal deficiency of the region in small field and garden 

 areas. These experiments comprise (a) removal of snow from 

 the field and garden early in the spring ahead of the season, 

 and (b) increasing soil and air temperature in the small garden 

 areas by the use of coal dust and specially constructed solar 

 radiators and reflectors. 



Experiments on the removal of snow were conducted in 

 1947-1949 both on hillside and bottomland fields. Local lignite 

 dust of the Healy Valley Coal Mine has been used for this pur- 

 pose. In 1947 coal dust was scattered on one yard squares with 

 application of two pounds of lignite per square at the end of 

 March. Bright sunshine in the first days of April cause rising 



