72 PRODUCTIVE FARMING 



from rains. Such bad effects can usually be remedied by the 

 application of practical methods. The aim should be to 

 bring the soil into suitable condition for the production of 

 large crops. 



Kinds of Improvement. The improvement may be k 

 several regards: 



1. In its physical condition. 



2. In its chemical make-up and food-yielding power. 



3. In its moisture-holding power. 



4. In its germ life or bacteria. 



m 



FIG. 41. Plowing under a crop of green manure to add humus to the soil. 



Tillage is one of the commonest ways to put soil in proper 

 physical condition to yield good crops. There are two main 

 types of tillage: Deep tillage, as with a plow (Fig. 41), and 

 shallow tillage, as with harrows and cultivators (Figs. 37 

 and 42). 



Objects of Plowing. The primary object of plowing a 

 field is to make a good seed bed by crumbling the soil and 



