98 THE ESSENTIALS OF AGRICULTURE 



third receiving no phosphate. These various lots of manure 

 were then compared as to their effect upon the yield of corn, 

 wheat, and clover grown in rotation through a series of several 

 years, the manure being applied at the rate of 8 tons per 

 acre on clover sod before plowing for corn. The following table 

 shows the money return per ton of manure in an average 

 round of the rotation : 



NET VALUE OF CROP INCREASE 

 MANURE AND TREATMENT pR TQN op MANUR 



Stall manure without phosphate $3-33 



Stall manure with rock phosphate 4.53 



Stall manure with acid phosphate 4.88 



Yard manure without phosphate 2.55 



. Yard manure with rock phosphate 3.63 



Yard manure with acid phosphate 4- 1 ? 



This experiment not only shows a good money return from 

 adding phosphate to the manure applied to a soil needing phos- 

 phorus but also shows that the stall manure which receives 

 proper care is more valuable than the yard manure which is 

 exposed to the weather. 



As a result of such experiments as this, it is becoming a 

 common practice in some parts of the country, particularly in 

 the eorn belt, to apply from 60 to 100 pounds of phosphate to 

 each, ton of manure before scattering it on the land. Phosphate 

 may.JDe applied from time to time as manure accumulates, or it 

 may Ipe added to the manure in the spreader (Fig. 42), plowing 

 it under for corn or other cultivated crops. 



108. Application of manure. Manure is usually applied before 

 planting a cultivated crop, such as corn, and is plowed under, 

 although frequently it is applied as a top-dressing to meadows 

 or wheat. The rate of application depends upon many condi- 

 tions, but 8 tons per acre once in four or five years may be 

 termed a good application for plowing under and from 4 to 6 

 tons an acre for top-dressing. On truck farms applications of 

 15 tons or more are common. The time of plowing manure 

 under depends mainly upon convenience and the crop to follow. 



