CHAPTER III 



PLANT FOODS 



Lime. Lime is known to every child. It is known, 

 too, that lime will dissolve slowly in water, and thus 

 become available for plant food. Large quantities of 

 lime are found in the soil. Of course, it comes from 

 the lime rock. 



Soda. Soda, or saleratus, as it is sometimes called, 

 is also easily dissolved in water. Soda is made from 

 common salt and the plants get it from the soil. 



*Iron Oxide. Iron oxide gives the red or yellow 

 color to rocks and soils. It dissolves in water, especially 

 after a little acid is added. 



The Use of Acids. But what is an acid? The 

 commonest kind of acid, without which no farmer's 

 wife could well get along, is vinegar. Acids are 

 usually sour in taste, and their presence in the soil as- 

 sists water in dissolving rock. A copper penny can be 

 made bright, or an old brass ring to look like gold, 

 by rubbing it with a little vinegar. This is because 

 the acid dissolves off the tarnish and leaves the clean 

 surface exposed. Some of the plant foods dissolve 

 much more readily in water to which a little acid has 

 been added. Soda is a good example. Put a tea- 



* Iron- rust. 



