being inimtdiately dissolved by water and at once appropriated by 

 the plant, or like potash in ashes that can be soaked out. Plant- 

 food exists in this form onl}- to a limited extent. A man might 

 famish if locked up in a granary filled with wheat ; yet, a 

 chemist would say that there was enough food near him to feed 

 a hundred men. This illustrates how nature has stored much of 

 the plant-food in the soil. It has to go through many changes 

 before it can be appropriated by the plant. The soil is a factory 

 in which the work of preparation is carried on. 



5. llie soil is a laboratory . — Some of the agents employed in 

 this factory are film moisture, air and heat ; and if these are not 

 furnished in the proper extent and manner, the factory runs in 

 a sluggish 'Vay, if it does not stop altogether. Good tillage does 

 much to hasten the activities of this factory by allowing free 

 ingress to the soil of film moisture, air and heat. Air is neces- 

 sary for a supply of oxygen, and heat to facilitate fermenta- 

 tion and other vital processes. 



The importance of air and heat in the soil brings us to the 

 question of drainage. Air cannot enter a soil freely which is 

 filled wath standing water, and growth of micro-organisms is 

 stopped. 



6. Wet soils are cold. — Standing water is a great absorbent of 

 heat. If no provision is made to drain it away, it must be evapo- 

 rated awa3\ Thereby heat is lost. The soil is cold. A great 

 many barrels of water can be standing on an acre of ground and 

 not attract much attention. 



To appreciate the amount of heat necessar}' to evaporate water 

 one has onh^ to chop, split and burn beneath a caldron kettle 

 enough wood to evaporate a barrel of water. Every barrel that 

 is evaporated from the soil b}^ the sun absorbs as much heat as 

 is contained in the wood used under the kettle. The soil and 

 plants are perhaps chilled for want of that heat. This is the 

 reason that a wet soil is said to be cold. 



7. D?'ai?ied soils resist df ought. — Some farmers have the notion 

 that well drained soil will not withstand a drought as well as 

 an undrained soil. The contrary is true. Everyone who has 

 tilled the soil is familiar with places that are wettest in a wet 

 time and driest in a dry time. When these places dry at all, they 



