322 SOILS: PROPERTIES AND MANAGEMENT 



These average readings, taken at different points, are 

 supported by the data of other observers. 1 It is apparent 

 that seasonal variation of soil temperature is considerable, 

 even at the lower depths. The surface layers of soil seem 

 to vary nearly in accord with the air temperature, and 

 therefore exhibit a greater fluctuation than the subsoil. 

 In general the surface soil is warmer in spring and sum- 

 mer than the lower layers, but cooler in fall and winter. 

 The following data taken at Lincoln, Nebraska, may be 

 of interest : 



AVERAGE MONTHLY TEMPERATURE READINGS 2 TAKEN AT LIN- 

 COLN, NEBRASKA. AVERAGE OP TWELVE YEARS. 



1 Ebermayer, E. Untersuchungen iiber das Verlialten 

 Verschiedener Bodenarten gegen Warme. Forsch. a. d. Geb. 

 d. Agri-Physik, Band 14, Seite 195-253. 1891. 



2 Swezey, G. D. Soil Temperatures at Lincoln, Nebraska. 

 Nebraska Agr. Exp. Sta., 16th Ann. Rept., pp. 95-102. 1903. 



