SOIL AS A MEDIUM FOR PLANT GROWTH 9 



Action of acid. — What is the result if the specimen is treated 

 with a few drops of acid ? Explain. 



Flame. — Hold a small fragment of each mineral in the flame. 

 Observe fusibility and change of color. Is the flame given any 

 color which is characteristic ? 



Exercise II. — Study of soil-forming rocks. 



Materials. — Small specimens of granite, basalt, shale, slate, 

 limestone, sandstone and quartzite. 



Procedure. — Study the color, texture, and structure of each 

 sample. Identify the minerals present and from this determine 

 the plant-food materials carried by each rock. Be prepared to 

 identify unlabeled samples in laboratory and field. 



Exercise III. — To show that plants give off water. 



Materials. — Plant growing in small pot, a tumbler. 



Procedure. — Place a tumbler over a small plant and observe 

 the condensation of moisture on the sides. Where does this mois- 

 ture come from ? What was its original source ? How do plants 

 give off water? Explain uses of water to the plant. 



Exercise IV. — Conditions for plant growth. 



Materials. — Small flower pots, rich soil, oat seed. 



Procedure. — Fill four small flower pots with a rich garden loam. 

 Moisten well and plant with oat seeds. When seedlings are a week 

 old, thin to desired number of plants. Grow for a few weeks under 

 optimum conditions and then subject them to the following condi- 

 tions : 



Pot 1. — Sunshine and optimum water. 



Pot 2. — Sunshine and minimum water. 



Pot 3. — Cold, shade, and optimum water. 



Pot 4. — Dark and optimum water. 



Observe results and explain. More pots with other conditions 

 may be tried at the pleasure of the teacher. , 



Exercise V. — Effect of the different plant nutrients. 



Materials. — One-gallon flower pots, very poor sandy soil, nitrate 

 of soda, acid phosphate, muriate of potash, barley seed. 



Procedure. — Fill five flower pots to within an inch of their tops 

 with poor sandy soil. It is essential to the success of the experiment 

 that the soil be poor, and also that it shall be surface soil and con- 



