WINTER INJURY TO THE ROOTS 



303 



The Pennsylvania figures are for State College, 1892-1896 inclusive; Idaho, 

 for Moscow, 1903-1904 (Idaho Exp. Sta. Bui. 49); Minnesota, 1889 (a mild 

 winter); Wyoming, averages for Laramie, 1895, 1898, 1899; Nebraska, from 

 Table 39; Michigan, selected as typical, from Mich. Agr. Exp. Sta., Tech. Bui. 

 26, p. 104; Woburn, England, 2d Rept., Woburn Experiment Farms (1900); 

 Colorado, Fort Colhns; lUinois (Urbana), (1897-1916); from Bui. 208, 111. Agr. 

 Exp, Sta.; Alabama, from Ala. Agr. Exp. Sta. Bui. 10. 



Table 40 is arranged from the same source and is introduced to 

 show absolute minima at several depths, over a series of years. 



Table 39. — Average Soil Temperatures at Lincoln, Neb.is" 

 (Degrees Fahrenheit) 



T.\BLE 40. — Minimum Soil Temperatures at Lincoln, Neb."" 

 (Degrees Fahrenheit) 



Data incomplete. 



The maximum depth of frost penetration at the same point has been 

 reported as detailed in Table 41. Recently, however, it has been shown 



