CULTIVATION OF WHEAT 65 



Increases the yield, is most destructive to weeds and insects, 

 and is the most economical in farm management. For winter 

 wheat, the ground is plowed as soon after harvest as is practi- 

 cable. This destroys the weeds before they ripen their seed 

 and gives time for a compact seedbed. The pulverized surface 

 soil more readily retains and absorbs moisture, upon which, 

 in the absence of vegetation, no demands are made by growth. 

 The depth of plowing should vary with the climate and with 

 the nature of the soil and the subsoil. The limits of the va- 

 riations usually found advantageous are between four and 

 eight inches in depth. 



Subsoiling. As the common plow is in effect a wedge pass- 

 ing through the soil on a horizontal plane, the uppermost layer 

 of the subsoil is compacted at each plowing. This renders the 

 subsoil more impervious to water and roots. Subsoiling con- 

 sists in breaking up the subsoil, and does not necessarily in- 

 volve changing the relative positions of subsoil and topsoil. 

 Judged by experiment station results, it does not seem to be an 

 economical operation. 



The Seed Bed. Soil, on account of its fine texture or wet 

 condition, may be lumpy after plowing. The spaces in it are 

 then very irregular in size, and the sort is in a poor condition 

 to draw up water from below, or to furnish uniform germinat- 

 ing conditions for the seed. In such cases it is customary and 

 advisable to work the soil with a harrow, roll, or other im- 

 plement until the larger lumps are broken and the surface be- 

 comes smooth and even. The seed bed is then ready for the 

 sowing. Thorough preparation conserves the moisture, dimin- 

 ishes winterkilling, and increases the yield. In both the 

 spring and winter wheat districts of the Mississippi valley, it 

 is a general practice to sow without plowing on land that has 

 produced corn the preceding year. In the case of winter 

 wheat, the grain may simply be drilled between the rows of 

 co*rn, with a five-hoe drill; or the seedbed may first be prepared 

 with a disc or tooth harrow. Corn ground for spring wheat 

 also is often prepared by using an implement of the disc har- 

 row type. 



SEEDING. 



Sowing. There are three methods of sowing wheat: Broad- 

 casting, which scatters the seed evenly over the ground; drill- 



