CHAPTER XII 



ROTATION OF CROPS AND CONSERVATION OF SOIL 



FERTILITY 



307. Object of Crop Rotation. — The object of the 

 systematic rotation of crops is to conserve the fertility 

 of the soil, and at the same time to produce larger 

 yields. In order to accomplish this, the food require- 

 ments of different crops must be met by good cultiva- 

 tion and proper manuring. Rotations must be planned 

 according to the nature of the soil and the system of 

 farming that is to be followed. For general grain 

 farming a different system must be practiced than for 

 exclusive dairying. Whatever the nature of farming 

 the whole farm should gradually undergo a systematic 

 rotation. If the farm is uneven in soil texture, differ- 

 ent rotations must be practiced on the various parts. 

 There is no way in which soils are more rapidly de- 

 pleted of fertility than by the continued culture of one 

 crop. In exclusive wheat raising for example the 

 losses which occur are not confined to the fertilitv re- 

 moved in the crop but may take place in other ways 

 as described in the chapter on nitrogen. When wheat 

 is properly grown in alternation with other crops, 

 losses of nitrogen are reduced to the minimum. 



When remunerative crops can no longer be produced 

 the soil is said to be exhausted. Soil exhaustion may 



