136 



TILTH AND TILLAGE 



in changing the structure of such soils, because the fine roots and 

 other organic matter prevent the individual grains from running 

 together. This explains why sod ground and some black, crummy 

 soils can be plowed when quite wet without any appreciable harm. 

 When the roots and organic matter are used up, the soil loses its 

 acquired looseness and crumbly characteristic. Even sandy soils 

 till better when they contain a good supply of organic matter. 

 Because of its influence on soil structure and on tillage, the oi'ganic 



FiQ. 66. — An excellent seed bed prepared for alfalfa. 



matter of soils should be maintained, and in many soils, increased 

 if possible. 



Tillage Tools. — Numerous kinds of implements have been 

 devised to prepare the ground for planting, and especially to care 

 for many of the crops during early growth. There are many differ- 

 ent kinds of plows, harrows, rollers, clod crushers, weeders and 

 cultivators. Aside from these there are many seeding and planting 

 implements which in themselves perform various tillage opera- 

 tions in addition to sowing the seed. 



Frequently the real purpose of a tillage implement, or the 

 principle upon which it is built, is overlooked; and too often a 

 machine is purchased merely because of some new device, or some 

 extra lever, rather than on the quality of the work it can do, or 



