EXPERIMENTAL WOBK WITH RAW EOCK PHOSPHATE. 



87 



In 1897 the field was divided into three tracts containing 20 

 plots each, and a three-crop rotation of com, wheat, and clover 

 begun, so that each crop was grown every year and each tract received 

 every third year the fertilizer treatments outlined below. 



A quantity of manure from the stable, where it had collected under 

 the feet of animals kept continually in their stalls, was taken and 

 divided into five equal parts, four of which were treated with various 

 reenforcing materials at the rate of 40 pounds to the ton of manure. 

 The fifth portion was left untreated. Equal or equivalent amounts 

 of manure from the open barnyard were similarly treated with the 

 same materials. After standing for some time the manure thus 

 treated was spread upon clover sod at the rate of 8 tons to the acre, 

 and plowed under for corn which was followed by wheat and clover. 

 During the first three seasons soy beans were grown and plowed 

 under, since clover was a failure. The arrangement of the plots is 

 shown in the following diagram taken from the Ohio station reports; 

 and the average yields per acre for 18 crops ^ and the increases in 

 yield due to the various applications are given in Tables LIII 

 and LIV. 



Arrangement of plots and plan of fertilizing in experiments tvith manure; 

 plots one-sixteenth acre each. 



11. 



Nothing. 





Nothing. 





1. 



12. 



Yard manure, gypsum. 





Yard manure 



floats. 



2. 



13. 



Stall manure, gypsujQ. 





Stall manure, 



floats. 



3. 



14. 



Nothing. 





Nothing. 





4. 



15. 



Yard manure, untreated. 



Section 



Yard manure 



acid phosphate. 



5. 



16. 



Stall manure, untreated. 



A. 



Stall manure. 



acid phosphate. 



6. 



17. 



Nothing. 





Nothing. 





7. 



18. 



Chemical fertilizer. 





Yard manure 



kainit. 



8. 



19. 



Chemical fertiHzer. 





Stall maniire, 



kainit. 



9. 



20. 



Nothing. 





Nothing. 





10. 



11. 



Nothing. 





Nothing. 





1. 



12. 



Yard manure, gypsum. 





Yard manure 



floats. 



2. 



13. 



Stall manure, gypsum. 





Stall manure. 



floats. 



3. 



14. 



Nothing. 





Nothing. 





4. 



15. 



Yard manure, untreated. 



Section 



Yard manure 



acid phosphate. 



5. 



16. 



Stall manure, untreated. 



B. 



Stall manure, 



acid phosphate. 



6. 



17. 



Nothing. 





Nothing. 





7. 



18. 



Chemical fertilizer. 





Yard manure 



kainit. 



8. 



19. 



Chemical fertilizer. 





Stall manure. 



kainit. 



9. 



20. 



Nothing. 





Nothing. 





10. 



11. 



Nothing. 





Nothing. 





1. 



12. 



Yard manure, gypsum. 





Yard manure 



floats. 



2. 



13. 



Stall manure, gypsum. 





Stall manure. 



floats. 



3. 



14. 



Nothing. 





Nothing. 





i. 



15. 



Yard manure, untreated. 



Section 



Yard maniu-e. 



acid phosphate. 



5. 



16. 



Stall manure, untreated. 



C. 



Stall manure. 



acid phosphate. 



6. 



17. 



Nothing. 





Nothing. 





7. 



18. 



Chemical fertilizer. 





Yard manure 



kainit. 



8. 



19. 



Chemical fertilizer. 





Stall manure. 



kainit. 



9. 



20. 



Nothing. 





Nothing. 





10. 



1 This applies to all plots, except the commercial fertilizer plots tlie results of which are 

 the averages of 16 years. 



