50 
ELEMENTS OF AGRICULTURE. 
QUESTIONS. 
1. In how many ways does humus act upon the soil ? 
2. How are the properties of the soil divided ? 
3. What are the different opinions on the action of humus in the act Oi 
regetation ? 
4. Are there facts that sustain one or the other of these opinions ? 
5. Can these facts establish a general rule ? 
6. In what state is carbon found when absorbed by plants ? 
7. What is the action of humus on the physical properties of soil 1 
8 In what soils is humus most readily decomposed ? 
9 What substances ought in preference to be placed in calcareous soil? 
]LSJ What would they do in stiff soils ? 
