WATER AND AGRICULTURE 



pull up a plant by the roots, you do not find these hairs. 

 They are so delicate and so closely adherent to the soil 

 grains that they break off and remain in the soil. You 

 can see that the absorptive surface 

 of roots is multiplied very many 

 times by these millions of hairs. 



You should also note that roots, in 

 their growth, are positively attracted 

 by water; they grow toward it, and 

 when the water-supply is deeper than 

 usual plants may develop an unusual 

 depth of roots. In fact, the growth 

 of roots seems to be chiefly a sort of 

 groping and searching in the soil for 

 water. If you sprout seeds in a 

 suspended wire cage containing damp 

 moss, the rootlets that grow down 

 through the bottom of the cage will turn and grow up 

 again toward the water above them. 



QUESTIONS 



1. How can you prove that water evaporates from leaves? 



2. What is irrigation? 



3. What kinds of work are done by the United States Reclamation 



Service ? 



4. Why can't you grow a plant in a bucket of water? 



5. What kind of soil holds the most water? Why? 



6. What are root-hairs, and of what advantage are they to the 



plant ? 



. 36. -Young root-tips 

 ith root hairs; A shows 

 how the soil particles be- 

 come attached. After 

 J. M. COULTER. 



