160 



POMOLOGY 



suits. In one orchard ^ in which these observations were 

 made, it was found that the soil temperature was lowest un- 

 der the heaviest vegetation and highest under clean tillage 

 during the summer and the reverse in winter; also the heav- 

 ier the vegetation, the cooler the soil during the summer 

 and the warmer in the winter. The following figures show 

 the effect of the soil treatment during the growing season: 



Table XXXIX 



AVERAGE SOIL TEMPERATURE 

 TILLED AND COVER-CROP PLOTS AT 8 INCHES. N. H. EXP. STA. 



Monthly average, April to September. Records made at 2 p. rn. daily 



April . . . 

 May. . . 

 June. . . 

 July. . . 

 Aug . . . . 

 Sept . . . 

 Average 



42.5 

 54.7 

 57.9 

 65.7 

 65.2 

 61.1 

 57.8 



The depth of freezing in these same plots is shown at a 

 time when the soil was supposedly frozen to the greatest 

 depth of the winter. 



Table XL 



N. H. Agr. Exp. Sta. Tech. Bull. 12. 1917. 



