120 Bulletin 174. 



itself, acts in such a manner as to make plant-food already in the 

 soil more available, or which improves its texture. 



21. /*' the soil in your garden sour? Try it. 

 See Reading-Lesson No. 3, page 7. 



22. In what inaterials can yonhuy j^hosphoric acid for fertilizer 

 purposes f 



The most common materials are .orms of hone. South Carolina 

 rock and Florida rock are ancient deposits of fossilized hone. Ground 

 fresh bones are sometimes used as a source of phosphoric acid. 



23. In what can you huy potash f 



The common commercial forms of potash are sulfate of potash 

 and muriate of potash. Wood ashes are also a source of this plant- 

 food. 



24. In what can you huy nitrogen ? 



Sulfate of ammonia and nitrate of soda are common forms. Cot- 

 ton-seed meal, dried blood and tankage are some of the organic sources. 



25. A7'e there any home fertilizers, or common farm materials 

 {aside from ham manure), in ivhich you can get these elements f 



The plowing under of green-crops, like clover, peas, vetch and 

 the like will furnish nitrogen; wood ashes furnish the only "'home 

 supply " of potash ; phosphoric acid must usually be purchased from 

 the dealers. 



NO. 4. HOW THE PLANT GETS ITS FOOD P^ROM THE SOIL. 



1. Do the root-hairs finally hecome roots, or do they stay on as 

 the main root grows f 



The root-hairs never become roots. As the young rootlets which 

 bear the root- hairs enlarge and their tissues become hard, the n tot- 

 hairs perish. 



2. Are there root-hairs on old roots f 

 No. 



3. On what part of the roots are the root-hairs f 

 On the young, tender rootlets. 



4. Where does the radish plant, which you grew in moss or cloth, 

 get nourishment fm' making the first root-hairs f 



This nourishment probably comes from the food-material stored 

 up in the seed. 



