152 EXPERIMENTS UPON GRASS LAND 



TABLE LVII. Produce of Hay per acre. Average over the period of 57 

 years (1856-1912), the 10 years (1903-1912), and the individual year 

 1912. Rothamsted. Total of first and second crops (if any). 



* Including Potash, first 6 years. 

 t After the change. Before the change 42-9. 

 t >> 49-5. 



5 .. ,, 80-6. 



85-4. 



1 54 years only (1859-1912). 

 ** 55 years only (1858-1912). 

 ft 42 years (1856-97). 

 }{ 15 years (1898-1912). 



Table LVIII. shows the first crops only for six successive 

 ten-year periods. 



In dealing, however, with the produce of grass land, which is 

 a mixed herbage consisting of many different species of grasses, 

 leguminous plants, and other orders, it is not sufficient to 

 consider only the gross weight of produce. The various 

 species are differently stimulated by particular manures ; even 

 among the grasses themselves, such a difference of habit as a 



