1 88 ECONOMIC PLANTS 



Experiments have shown that early plowing and early 

 seeding of winter wheat, preferably the first week in 

 September in the northern states and late in Septem- 

 ber or early in October in the states farther south, pro- 

 duce the best yield. The ground for spring wheat 

 planting should be plowed the previous autumn and 

 the seed sown in the spring as early as possible. 



If the crop rotation brings wheat after clover or 

 corn, little or no added nitrogen will be required, and 

 if the preceding crop has been furnished lime, potash, 

 and phosphorus, no additional fertilizer will be needed. 



Preparation of Seed Bed. --The practice as to depth 

 of plowing varies in different localities. As wheat has 

 a shallow rootage, it has been thought necessary to 

 plow but four to seven inches in depth. This allows 

 the roots to spread out on the subsoil where they re- 

 ceive the maximum amount of moisture and at the 

 same time a plentiful supply of air in the plowed sur- 

 face. 



Shallow plowing has resulted in early exhaustion 

 of the topsoil and consequent lessened yields of wheat, 

 so that, as usually practiced, deep plowing stirs up the 

 soil to a depth of six to eight inches and has the fol- 

 lowing advantages : 



(a) It allows the soil to absorb a large amount of 

 the rainfall. 



(&) It renders available for plant growth a larger 

 amount of plant food. 



(c) It buries many weeds that would otherwise 

 spring up to choke the wheat. 



Many who practice deep plowing use the subsurface 

 packer (see page 95) to reestablish capillarity between 

 the surface and the subsoil. 



