48 SOIL AN IMPORTANT FACTOR 



Requirements and Conditions for Germination. — For a most 

 vigorous germination seeds require (a) a favorable moisture supply 

 in the soil; (b) sufficient air for oyxgen; (c) favorable temperatin-e, 

 and (d) good tilth. It is to be noted that a germinating seed 

 requires no plant-food elements from the soil or carbon dioxide 

 from the air. It does not need them, since nature has surrounded 

 the germ in the seed with a storehouse of food. As soon as the 

 dormant life quickens, this store of food is drawn upon to nourish 

 it. Water and oxygen are required for the same reason that ani- 

 mals require them; viz., for life processes. And warmth is just as 

 essential in promoting these life processes in a germinating seed 

 as it is in an animal body. 



Just as some aninials can tolerate lower temperatures than 

 others, so it is with germinating seeds. Farmers in different sec- 

 tions of the country learn by experience when it is the best time 

 to plant various seeds to meet favorable temperature conditions. 

 No farmer in a temperate zone would think of planting beans and 

 corn as the first crops in early spring. Again, corn will rot under 

 temperature conditions that will permit germination of winter 

 wheat and rye. 



When lands are wet and cold, a farmer can help in a large meas- 

 ure to create more favorable temperature conditions in the soil 

 by draining such lands. 



The supply of air and moisture and the temperature conditions 

 for the planted seed are influenced in a large degree by the physical 

 condition of the soil or seed bed. In this connection much is said 

 and written concerning tilth. 



Tilth Defined. — ^Tilth refers to the physical condition of the 

 seed bed with respect to mellowness and firmiiess, indicating 

 whether or not the soil is capable of favoring germination or 

 promoting plant growth. 



Good Tilth. — ^When a soil has a certain degree of mellowness 

 and firmness favorable to seed germination and plant growth, it 

 is said to have good tilth; for example, a loamy soil having a fair 

 degree of firmness. 



Poor Tilth. — ^A soil is in poor tilth when it is too loose, very 

 lumpy or very hard and compact. These conditions are unfavor- 

 able to germination and plant growth. 



Tilth does not indicate a rich or poor soil. The poorest soil 

 imaginable may have excellent tilth; a poor sand, for example. 



The only substance a germinating seed takes from the soil is 



