192 THE SYSTEM OF FAKM-YARD MANURING 



f g the produce of oat-corn, the lines f h that of oat- 

 straw ; in Fig. IY., the lines i ~k the produce of clover, 

 on the unmanured plots of ground on which the experi- 

 ments were made in Saxony. 



Now if we assume that the roots of the rye and of 

 the other plants, on the several fields, were of the same 

 length and condition, it is quite certain that the roots 

 of the cereals on the field at Mausegast found, in their 

 way downwards, much more nutriment than those in 

 the Cunnersdorf field : the corn line is twice as high, 

 and the straw-line one-third higher, in the former than 

 in the latter. 



With an equal number of plants, and an equal 

 length of root, certain nutritive substances required by 

 corn were twice as close in the Mausegast as in the 

 Cunnersdorf field. The line in Fig. IV. representing 

 the produce of clover is ten times as high for Cunners- 

 dorf as for Oberbobritzsch, which means that the nutri- 

 tive substances required by clover were ten times as far 

 asunder in Oberbobritzsch as in Cunnersdorf. 



In comparing the produce of several fields, the close- 

 ness of the nutritive substances in the soil is in inverse 

 proportion to the height of the lines in the table indi- 

 cating the amount of produce. 



The longer the lines, the closer are the nutritive 

 substances in the various soils ; the shorter the lines, 

 the more widely asunder do the substances lie. 



For instance, the lines indicating the produce of 

 potatoes at Kotitz and Oberbobritzsch are as 18 to 9 ; 

 the potato crop at Kotitz was twice as high as that at 

 Oberbobritzsch. Hence it follows that the distance 

 between the nutritive substances was in inverse ratio, 

 that is, as 9 to 18 ; in the field at Kotitz they were 

 twice as close together as in the other. 



This mode of viewing the matter is calculated to 

 lead, in many cases, to more definite ideas respecting 

 the cause of the exhaustion of a field. 



The corn and potato crops, for instance, took away 

 phosphoric acid and nitrogen from the arable surface 

 soil at Mausegast, and the barley plant next in rota- 



