WHEAT. 



187 



It will suffice to confine attention to the amount of dressed Produce of 

 grain per acre, in bushels. The difference in yield of the fjj/'gj 

 various plots in the best and worst of the forty seasons is worst 

 very striking. The unmanured, the mineral manured, and seasons - 

 the heavily nitrogenous manured plots, all suffered severely 

 in the bad season. In most cases the difference between the 

 produce of the best and the worst season approached, and in 

 two (plots 6 and 7) it actually exceeded, the average produce 

 of the plots. From these facts it will be seen how easy 

 it is to form wrong conclusions as to the effects of different 

 manures, if experiments are conducted in one season only, 

 or in only a few seasons, and if the characters of the seasons 

 are not studied. 



Not only season, but soil and locality also must exercise -Eject of 

 an influence. The Eothamsted results are, of course, obtained jj^jjET 

 on one description of soil, and in one locality. Eeference to 

 the following Table (54) will show the results obtained in 

 experiments conducted at Eothamsted during the same 8 

 years in two different fields : at Woburn, for 7 years ; at 

 Holkham, Norfolk, for 3 years ; and at Eodmersham, Kent, 

 for 4 years. 



TABLE 54. — Results of Experiments on the growth of Wheat 

 by different Manures, on different Soils, in different 

 Localities, and in different Seasons. 



i By ammonium-salts=only 43 lb. nitrogen. 



Thus, in experiments made on very various soils, in 

 different conditions from previous treatment, and in various 

 seasons, the general character of the results obtained with 

 each of the four very different conditions as to manuring 

 was accordant. The only marked exception was in the case 

 of Eodmersham, Kent, where the condition of the land was 



