306 SOILS 



soil makes a strong meadow, keep the land in hay 

 up to the point where the soil would be injured and 

 me yield reduced by retaining it longer in sod. If 

 corn is the money crop, grow corn to the limit of 

 the soil's patience and rotate it with other crops 

 that are most serviceable in maintaining the fer- 

 tility of a first-class corn field. Maximum profit 

 is the main point to observe in planning a rotation, 

 bearing in mind that no crop is profitable if 

 it is secured by robbing and impoverishing 

 the soil. 



2. A rotation should preferably contain at least 

 one crop that improves the soil. This "green 

 crop" may be grown specifically for a green- 

 manure, as a catch crop of rye after corn; or a 

 crop which is harvested, but which nevertheless 

 improves the soil by its growth, as clover or cow- 

 peas. The improvement may be in texture, by 

 plowing under humus; or it may be in actual 

 enrichment, by growing a leguminous crop, as is 

 considered in the next chapter. If it is at all ex- 

 pedient, a leguminous crop should be included in 

 the rotation. 



3. If possible, the rotation should include crops 

 that feed at different depths, and that are dissimilar 

 in habits of growth. Deep-rooting crops should al- 

 ternate with shallow-rooting ones. 



4. If the money crop is sown, the rotation should 

 include a "cleanser," a crop that is cultivated, so 

 that the land may be kept free from weeds. In 

 Europe, roots, as turnips, potatoes and swedes, are 

 commonly used as a cleanser; in this country corn 

 and potatoes are most largely grown for this 

 purpose. 



Reducing these suggestions to a simple form, a 

 rotation ought to contain a money crop, a manurial 



