EXPERIMENTS IN SOIL CHEMISTRY 275 



No. i. Leave the soil as it was when brought in. This 

 we call a check pot. 



No. 2. Mix thoroughly with the soil four grams of 

 dried blood or the same amount of potassium nitrate or 

 sodium nitrate. 



No. 3. Potassium chloride four grams, or same amount 

 of kainit. 



No. 4. Bone meal six grams, or same amount of sodium 

 phosphate. 



No. 5. Mix together four grams of dried blood and six 

 grams of bone meal. 



No. 6. Mix four grams of potassium chloride and six 

 grams of bone meal. 



No. 7. Potassium chloride four grams, and dried blood 

 four grams, or saltpeter. 



No. 8. Potassium chloride four grams, dried blood or 

 saltpeter four grams, and bone meal six grams. 



No. 9. No fertilizer, hence another check pot. 



No. 10. A small handful of slaked lime. 



It will be of interest to start the same experiments in 

 different soils. If some of the children will bring in some 

 worn-out soil, a set of experiments in this will probably 

 bring some good results. 



Have the children bring in some soil in which red 

 clover has been growing. Place some of it in a hot 

 oven for an hour or more. This will kill the bacteria 

 that are in it. Put this in a pot and plant red clover 

 seeds in it. 



Place in another pot some of the soil that has not been 

 sterilized and plant clover in this. Water and treat both 

 exactly alike. When the plants have grown to be quite 



