184 THE ROTHAMSTED EXPERIMENTS. 



the 40 years, but a magnesia-salt instead ; but it had received 

 566 lb. of potash during the preceding 8 years. Thus, plot 

 11 received no potash throughout the 48 years; plot 12 none 

 during the 40 years, but there would be a residue from the 

 applications during the preceding 8 years ; plot 13 received 

 potash every year of the 40, and a considerable quantity dur- 

 ing the preceding 8 years also ; and plot 14 none during the 

 40 years, but had a residue from previous applications. 



Complete analyses of the ash of the grain, and of the straw, 

 representing the produce of each of the four successive 

 10-yearly periods of the 40, of each of the four plots, have 

 been made, by Mr E. Kichter, formerly of the Eothamsted 

 Laboratory, but now of Charlottenburg, Berlin. We have, 

 therefore, in the comparison of the amounts of potash in the 

 crops of plots 12 and 14, with only residues of it from long 

 previous applications, with those on plot 11 without any 

 supply at all, and on plot 13 with both residue and an 

 annual supply of it, the means of judging whether the 

 residues from the applications during the preceding 8 years 

 had been effective. 

 Amount of Referring to the amounts of potash stored up in the total 

 ^hmtas P r °duce (grain and straw together), the table shows that, on 

 influenced plot 11, without any supply, the amounts in the crop per 

 by manure. acre p er annum were, over the four 10-yearly periods — 30.9, 

 26.0, 18.3, and 18.2 lb. ; showing, therefore, a very great 

 decline in the amount of potash in the crop where none had 

 been supplied. On plot 12, with no supply during the 40 

 years, but with residue from applications during the pre- 

 ceding 8 years, the amounts in the crops per acre per annum, 

 over the successive periods were — 45.4, 37.8, 26.5, and 30.4 ; 

 that is, very much more than without any supply at all. 

 On plot 14, again, without annual, but with residual supply, 

 the amounts in the crops were — 49.8, 39.1, 27.2, and 31.1 

 lb. ; or even rather more than on plot 12 with residual 

 supply only. Lastly, the amounts of potash in the crops 

 on plot 13, with both annual and residual supply, were — 53.2, 

 55.2, 40.8, and 50.6 lb. ; or very much more than on either 

 of the plots with residual supply only. Or, if we take the 

 average amounts of potash in the crops per acre per annum 

 over the 40 years, they were — on plot 11 without any supply, 

 23.4 lb. ; on plot 12 , with only residue from previous appli- 

 cations, 35.1 lb. ; on plot 14, also with only residue, 36.8 lb. ; 

 but on plot 13, with liberal both previous and annual supply, 

 Potash 50.4 lb. That is to say, there was about \\ time as much 

 In^i store d up in the total produce over the 40 years where there 

 was accumulation from previous applications, as where none 

 had been supplied, and more than twice as much where there 



