32 



SOILS AND PLANT LIFE 



Conclusions. — Market gardeners always trjf to select 

 a dark, sandy soil for their early vegetables. Give one 

 reason why this Idnd of soil warms up earlier in the spring. 

 Lime, added to a clay soil, tends to gather the fine parti- 

 cles into small grains. Would you expect the tempera- 

 ture of a clay soil to be somewhat higher after a dressing, 



Fig. 10. — Thermometers in the soil. 



or application of lime was added? In Exercise 10, the 

 amount of air space was found to be greater in the soil 

 containing humus from the old fence row than in that 

 from the center of the road. Would you expect the tem- 

 perature of the soil in the sun along the fence row to be 

 higher than that in the center of the road ? Why ? If you 



