36 



CROPPING SYSTEMS 



Some Results With Rotations. A good example of the effect 

 of rotation on crop production, in comparison with continuous crop- 

 ping to one crop, is shown in the following data from the Ohio 

 Experiment Station. In the year 1894, two similar fields were laid 

 out in plats. On one field wheat has been grown continuously, a 

 part of the plats with fertilizer and a part without. On the second 

 field, a five-year rotation was laid out, consisting of corn, oats, wheat, 

 clover, and timothy. These plats were repeated, so wheat was har- 

 vested every year. 



Continuous Vs. Five-Year Rotation WithWheati 



In the continuous wheat, the fertilizer was applied every year, 

 while in the rotation, fertilizer was only applied to part of the crops. 

 The average annual application was as follows : 



System 



Continuous 160 



Rotation . 64 



100 

 52 



Nitrate 

 of soda, 

 pounds 



160 

 96 



Only about half as much fertilizer was used per year with the 

 rotation crops, but wheat was one of the crops fertilized. 



In both cases, yield of crop decreased under continuous cropping, 

 even when heavy fertilizer was added. Yield has slowly increased 

 under rotation farming, even without fertilizer. 



Applying Fertilizers. It has been mentioned several times that 

 nitrogen, phosphates, and potash are the three elements that soils are 

 most likely to be deficient in. When a fertilizer contains the above 

 three elements it is called a complete fertilizer. A 2-8-3 fertilizer 

 means that 2 pounds of nitrogen, 8 pounds of available phosphoric 



Experiment Station Bulletin 231; p. 12, 1911. 



