The Plant as Related to the Soil 



43 



with freshly boiled well-water. The water should be boiled to drive 

 out all the oxygen, and a layer of cooking oil used to prevent more 

 being absorbed from the air. Insert cuttings of willow or Wandering 

 Jew, and keep in a warm place for a 

 week or more. Note the time when 

 the rootlets appear on the cuttings. 



68. Moisture Promotes Root 

 Growth on Stems. A continu- 

 ous supply of moisture stimulates 

 root growth. Portions of stems 

 kept in contact with moist soil for 

 some time develop roots, as is often 

 noticed in fallen corn stalks, to- 

 mato vines, and potatoes. To make 

 roots develop on cuttings of roses, 

 figs, grapes, etc., we bury them in 

 moist sand, loam, or sawdust. (See 

 K 194, Layerage.) 



69. The Ideal Soil for cultivated plants is one having 

 an abundant supply of moisture, containing plenty of 

 soluble plant food, and so porous that air can circulate 

 freely and come in contact with the roots. The soil 

 may be too dense, or so compact that the air and water 

 cannot circulate. It may be too wet, that is, have so 

 much water that all the air is forced out. In very wet 

 weather, the roots are often noticed growing out of the 

 surface of the ground. 



70. Improving the Tilth of the Soil. We have already 

 learned that the particles of the soil should be suffi- 

 ciently fine for the root-hairs to grow between them. 

 The particles may be so fine and so run together that 

 neither the air nor the root-hairs can enter the soil. 

 This condition is just as unfavorable for the roots as 

 the coarse, lumpy soil. The texture, or physical con- 



Fig. 28. Arrangement for 

 showing the effect of 

 the exclusion of air on 

 plant growth. A film of 

 cooking oil prevents the 

 boiled water from ab- 

 sorbing oxygen from the 

 air. 



