RELATIVE PROPORTION OF CORN AND STRAW. 197 



In Cunnersdorf as (11) K : (29) aK St. 



" Kotitz as (12) K : (30) aK St. 



" Oberbobritzsch as (14) K : (30) aK St. 



As before remarked, the constituents represented by 

 the symbols K and S differ merely in this, that K com- 

 prises nitrogen and phosphoric acid, while the other 

 constituents of K are common to both ; hence the dif- 

 ference in the corn crops of these three fields results 

 mainly from the fact, that the roots of the corn found 

 in the soil at Kotitz - f \ and at Oberbobritzsch T 3 r more 

 phosphoric acid and nitrogen in an available condition 

 than at Cunnersdorf. 



If the question is asked, how much phosphoric acid 

 and nitrogen must be added to the field at Cunnersdorf 

 in order to make the crop of corn equal to that of Ober- 

 bobritzsch, it would be a mistake to suppose that an 

 increase of T 3 T would be sufficient ; for the augmenta- 

 tion of the produce of corn is materially influenced by 

 the S constituents, the quantity of which varies greatly 

 in different soils and has not been ascertained. 



By the addition of nitrogen and phosphoric acid, a 

 certain quantity of the accumulated S constituents are 

 rendered effective or available, which before were not 

 so ; but while the produce of straw increases, not T 3 T , 

 but less of nitrogen and phosphoric acid remain over for 

 the formation of seed ; the exact quantity is limited by 

 the total amount of transformed St constituents. 



The closeness of the Stf constituents in different soils 

 may, however, be approximately ascertained from the 

 relative proportion of corn and straw obtained from a 

 plot manured with phosphoric acid and nitrogen, and 

 from an unmanured plot respectively. 



If the unmanured plot yields corn and straw in the 

 proportion of 1 : 2*5, and the manured plot gives a 

 larger crop in which the corn is to the straw as 1 : 4 

 (straw being in greater proportion), it is evident that 

 the St constituents preponderate in the latter field ; and 

 a much larger quantity of phosphoric acid and nitrogen 

 would have to be supplied in order that the field, cor- 

 respondently with its amount of Srf constituents, might 



