122 INDIAN CORN CULTURE. 



in place of the beans we sowed barley and red clover together. 

 The result was that the red clover sown with the barley was 

 so luxuriant as greatly to interfere with its growth, and this 

 too upon land where we had been trying to grow beans with- 

 out manure for 30 years. In spite of our having grown a 

 leguminous crop something had accumulated in the soil 

 which was more favorable to the growth of another legu- 

 minous plant than to that of a cereal crop." 



Plants also differ in use of ingredients of soil 

 fertility. Tobacco is notably a potash feeder, 

 while the clovers use comparatively more 

 nitrogen than phosphoric acid or potash. This 

 being the case, one kind of plant food might 

 be accumulating in the soil while a crop was 

 being grown upon it which made only a slight 

 drain upon that particular element. If no ma- 

 nure was put upon the land it is plain, in view 

 of these facts, that the land could be cropped 

 to better advantage by the rotation system 

 than by continuously growing the same class of 

 plants on it. ^ 



An important factor in rotation also bears 

 on the plant food left in the roots of the crop 

 last removed from the field. Gulley states* 

 that when either red clover or cowpeas are 

 grown on land of average fertility in the South 

 after cutting off the crop for hay the stubble 

 and roots on an acre of soil contain as much 

 nitrogen, phosphoric acid and potash that may 

 become available to the next crop as a dressing 



* First Lessons in Agriculture, 1892, p. 85. 



