EXPERIMENTAL WORK WITH RAW ROCK PHOSPHATE. 



47 



employed containing 30 pounds of soil each, and in series 2, pots one- 

 half this size (2 gallons) containing 15 pounds of soil were used. 



Series 1 was planted to tobacco the first year, followed by oats the 

 second year. Series 2 was planted to clover the first year, followed 

 the second year by tobacco. Series 3 was planted to wheat the first 

 year and to clover the second year. 



In each instance after the first crop was harvested the soil was 

 dried, emptied out of the pots, mixed thoroughly with the fertilizers 

 for the following crop, and then returned to the pots. The results of 

 these experiments are given in part in Tables XXII, XXIII, and 

 XXIV. 



Table XXII. — Yields of tobacco and oats obtained in pot tests with various 



fertilisers. 



SERIES 1.— TOBACCO (4-GALLON POTS). 



Fertilizer. 



Applica- 

 tion per 

 pot. 



Yield of 



stalks and 



leaves per 



pot. 



Increase 

 per pot. 



Relative 

 increase. 



None 



Limestone , 



Dissolved bone (24 per cent Pj O5) . 



Rock phosphate , 



Manure 



Do 



Rock phosphate 



15.0 

 3.8 

 20.0 

 35.0 

 35.0 

 20.0 



Grams. 

 113.8 

 12.0 

 10.3 

 13.2 

 9.7 



10.3 



Grams. 



-1.75 

 -3.75 

 —0.55 



-4.05 



-3.45 



Per cent. 



-12.7 

 -27.2 

 - 4.5 

 -29.4 



-25.1 



SERIES I.- 



-OATS (AFTER TOBACCO). 









Applica- 

 tion per 

 pot. 



Whole crop. 



Grain. 



Fert-ilizer. 



Yields 

 per pot. 



Increase 

 per pot. 



Yield 

 per pot. 



Increase 

 per pot. 



Relative 

 increase. 



None 



Grams. 



Grams. 

 147.5 

 61.0 

 83.0 

 68.5 

 93.5 



\ 84.0 



Grams. 



Grams. 

 1 10.1 

 13.5 

 15.0 

 13.4 

 16.5 



15.4 



Grams. 



Per cent. 



Limestone 



15.0 

 3.7 

 20.0 

 35.0 

 35.0 

 20.0 



13.5 

 35.5 

 21.0 

 46.0 



36.5 



3.4 

 4.9 

 3.3 

 6.4 



5.3 



33.6 



Dissolved bone (24 per cent P2O5) 



48.5 



Rock phosphate 



32.7 





63.4 



Do 





Rock phosphate 









I Average of 2 pots. 



Table XXIII. — Yields of clover and tobacco obtained in pot tests with various, 



fertilizers. 





SERIES n.— CLOVER (2-GALLON 



POTS). 







Fertilizer 



Application 

 per pot. 



Weight 

 of three 

 cuttings 

 per pot. 



Increase 

 per pot. 



Relative 

 increase. 



None 



Grams. 



Grams. 

 16.0 

 20.4 

 32.1 

 30.8 

 25.7 



1 27.6 



Grams. 



Per cent. 





7.5 

 L9 

 10.0 

 17.5 

 10.0 

 17.5 



4.4 

 16.1 

 14.8 



9.7 

 11.6 



27.5 



Dissolved bone 



. 100.6 





92.5. 



Manure 



60.6 



Rock phosphate 



72.5 



Manure 







