Manures Employed. 141 



superphosphate of lime (as plots 7, 9, 11, and 13), and nitrate 

 of soda containing nitrogen equal to that in the ammonia- 

 salts of plots 5, 9, and 13, 1858, and each year since. 



Plot 15. Nitrate of soda alone, same quantity as plot 14, 

 18 years, 1858-75 ; no nitrate, but sulphates of potash, soda, 

 and magnesia, and superphosphate of lime (as plots 7, 9, 11, 

 13, and 14), 1876, and each year since. 



Plot 16. Sulphates of potash, soda, and magnesia, and 

 superphosphate of lime (as plots 7, 9, 11, 13 and 14), and 

 half as much nitrate of soda as plot 14, 1858, and each year 

 since. 



Plot 17. Nitrate of soda alone, same quantity as plot 16, 

 1858, and each year since. 



Plot 18. Mixture containing the potash, soda, lime, 

 magnesia, phosphoric acid, silica, and nitrogen, of 1 ton of 

 hay, also sulphuric acid and chlorine, 1865, and each year 

 since. 



Plot 19. Nitrate of soda (same quantity as plots 16 and 

 17), sulphate of potash, containing the same quantity of 

 potash as the nitrate of potash of plot 20, and superphos- 

 phate of lime, 1872, and each year since. 



Plot 20. Nitrate of potash, containing the same quantity 

 of nitrogen, and the same quantity of potash, as the nitrate 

 of soda and sulphate of potash of plot 19, and super- 

 phosphate of lime, 1872, and each year since. 



A careful perusal and comparison of the preceding details 

 will enable the reader to comprehend the scheme underlying 

 the system of manuring, and to understand how the various 

 dressings dovetail in with each other, so that the effects of 

 each manure alone, and of two or more variously combined, 

 are provided for. 



In discussing the results on the various plots, it will be 

 useful to have some standard of comparison, such as may be 

 afforded between fair average yields of wheat, barley, and 

 meadow hay. For this purpose the following yields per acre 

 are assumed : 



