NEARNESS OF ELEMENTS OF FOOD IN SOILS. 11)7 



Oberbobiitzscli, which means that the nutritive sub- 

 stauces 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 in- 

 verse proportion to the height of the lines in the table 

 indicating the amomit of produce. 



The longer the hues, the closer are the nutritive sub- 

 stances in the various soils ; the shorter the lines, the 

 more widely asunder do the substances lie. 



For instance, the lines incUcating the produce of pota- 

 toes at Kotitz and Oberbobritzsch .are as 18 to 9 ; the 

 potato crop at Kotitz was twice as high as that at Ober- 

 bobritzsch. 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 Miiusegast, and the barley plant next in rotation, 

 which hkewise draws its nutriment from the surface soil, 

 found in the third year much less nutriment than the rye 

 plant which had preceded it. 



The elevations of the fines a b (Fig. I.) and/// (Fig. HI.), 

 taken inversely, show how much relatively greater 

 has become the distance between the particles of the 

 nutritive substances for the barley plant. Tlie barley- 

 corn requires for its formation the same nutritive su]>- 

 stances as the rye-corn. Now, as the produce of the 

 rye-corn was to that of the barley-corn in the proportion 

 of 22 : 12, this means, taken inversely, that the distance 



