5T 



vated field the soil will become darker where the tracks are (Fig. 

 30). This dai'ker appearance of the soil in the foot-marks is due to 

 the moisture which is there rising to the surface. The implement 

 of tillage makes the soil loose and breaks the capillary connection 

 between the lower layers of soil and the surface and the upward 

 passage of the water is checked. Where the foot-print is, the soil 

 has been pressed down again at the surface, the particles have been 





'-'«lb 





30. - " Foot-prints on the sands of time.' 



crowded closer together and capillarity is restored to the surface 

 and the moisture is free to escape (Fig. 31). In caring for flower- 

 beds, or even in growing plants in a pot in the school-room, it 

 is important that the surface of the soil be kept loose and mel- 

 low. Far better is a garden rake in a flower garden than a water- 

 ing pot. 



Experiment Wo. 8. — To show the imjDortance of the surface 

 mulch, fill several pots with a sandy loam soil, putting the same 



.4 cross section tJirougli one of the foot-prints. 



weight of the same kind of soil into each pot. In one pot pack the 

 soil firmly ; in another pot pack the soil firmly and then make the 

 surface loose. These pots of soil may then be put away to dry, and 

 by weighing each daily it can be readily determined what effects the 

 various methods of treatment will have upon the moisture-holding 

 power. 



29 449 



