CHAPTER XII 



ROTATION OF CROPS AND CONSERVATION OF SOIL 

 FERTILITY 



313. Object of Crop Rotation. The object of 

 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 culti- 

 vation and judicious 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 rotation is required 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 can 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 fertility re- 

 moved in the crop but there are other losses as described 

 in the chapter on nitrogen. When wheat is system- 

 atically grown in alternation with other crops, losses 

 of nitrogen are reduced to a minimum. 



When remunerative crops can no longer be produced 

 the soil is said to be exhausted. Soil exhaustion may 

 be due either to a lack of fertility or to the soil being 

 temporarily out of condition because of a one-crop 

 system and poor methods of cultivation. 



