78 



THE ROTHAMSTED EXPERIMENTS. 



General 

 view. 



should be the greatest reduction in Series 1, where no 

 nitrogen is supplied, is evidence of nitrogen exhaustion under 

 those conditions ; and that, within Series 2 and 3 respectively, 

 there should be the greatest reduction where the ammonium- 

 salts or nitrate is used without phosphates, is evidence of 

 phosphoric acid exhaustion in those cases. 



Leaving the results relating to the produce of each indi- 

 vidual year, or of limited series of years, as given in Tables 

 22 and 23, a general view of the effects of the sixteen 

 different conditions as to manuring is conveniently obtained 

 in the summary Table 24. There is there given the aver- 

 age produce over the forty years on each of the sixteen 



TABLE 24. — Summary showing the average produce of Bar- 

 ley PER ACRE PER ANNUM, OVER FORT? YEARS, BY DIFFERENT 



Manures. 



Plot. 



1000 lb. 



rape-cake 2 



=49 lb. 



nitrogen. 



DRESSED GRAIN PER ACRE, BUSHELS. 



STRAW PER ACRE, LB. 



TOTAL PRODUCE (GRAIN AND STRAW) PER ACRE, LB. 



1 Ammonium-salts = 86 lb. nitrogen first 6 years, =43 lb. next 10 years; 

 sodium nitrate = 43 lb. nitrogen each year since. 



2 2000 lb. rape-cake first 6 years, 1000 lb. since. 



