CONDITIONS AFFECTING GROWTH 7 



roots are not disturbed. Cultivation is especially 

 necessary and should be frequent in the spring and 

 after rains. The general practice is to cultivate 

 deep and often early in the season, and shallow and 

 less frequently as the season advances. 



Importance of soil temperature, — The roots of 

 plants can in no way take up plant food from the 

 soil without proper soil temperature. Ebermayer's 

 observations indicate that growth does not begin 

 with most cultivated crops until the soil has attained 

 a temperature of 45 to 48° F. and it does not take 

 place most vigorously until after it has reached 68 

 to 70°. It is at its maximum when the temperature 

 is 98°. J. B. Reynolds reports* that the best soil 

 temperature for bean growth is 90°. 



The seeding of general crops should not begin 

 until the thermometer will show the temperature of 

 the soil at the depth of planting well towards 70° F. 

 during the warmest portion of the day. A still 

 higher temperature would best be waited for in the 

 case of beans. It is a conceded fact that the more 

 quickly seeds germinate after they are placed in the 

 soil, the higher will be the percentage of seeds grow- 

 ing and, as a rule, the more vigorous will be the 

 plants. 



It follows, therefore, that the practice of 

 thoroughly preparing the seed bed before sowing or 

 planting must have the effect of decreasing the 

 capillary rise of cold water from below and its loss 

 by evaporation from the soil. This then would tend 

 to concentrate the sun's heat in the seed bed itself, 

 first, by lessening its rate of conduction downward, 

 and second, by diminishing its loss by lessening the 



•Ontario Agricultural college, Rpt of 1903. 



