CHOPS NOT IN PROPORTION TO NITROGEN IN SOIL. 299 



constituents of manures, it is impossible to ascribe to 

 the one an effect which does not equally apply to the 

 other. 



There can be no doubt that the nitrogenous com- 

 pounds in the ground often exert no influence in increas- 

 ing the crops, while those in the manures undoubtedly 

 produce a favourable effect. Hence the operation of 

 the nitrogenous compounds in the manure must have 

 depended upon causes which the ground did not sup- 

 ply ; and it is clear that the same efficacy can be given 

 to the nitrogenous compounds in the soil, if the farmer 

 will take care to bring into play the causes which pro- 

 duced the favourable operation in the manures. 



If we consider, for example, the crops yielded (see 

 pp. 148 and 151) by the two fields at Schleissheim in 

 an unmanured condition, and compare them with the 

 quantity of nitrogen in the soil, the result is 



Nitrogen, per hectare ( = 2 acres). 



To the depth of 10 inches. Produce. 



Corn. Straw. 



In Field 1 (p. 151), 1858 ... 2787 kilo. 115 kilo. 282 kilo. 

 In Field 2 (p. 148), 1857 ... 4752 " 644 " 1656 " 



Those who maintain that the crops depend upon 

 the nitrogen in the soil, would judge the results of these 

 two experiments somewhat in the following way : 



The amount of nitrogen in both fields is as 100 : 160 



The corn crops as ; 100 : 560 



If the crops are in proportion to the quantity of 

 effective nitrogen in the soil, it follows that the soil of 

 Field 2 contained, not only altogether, but even propor- 

 tionately, more than Field 1. If the corn crop in Field 

 1 = 115 kilogrammes corresponded to the fraction of 

 effective nitrogen in the whole amount of nitrogen = 

 2787 kilogrammes, then Field 2 ought to have yielded 

 257 kilogrammes of corn, supposing that the relative 

 proportion of active and inactive nitrogen were the 

 same as in Field 1 (for 2787 kilogrammes, nitrogen : 

 115 kilogrammes, corn = 4752 kilogrammes, nitrogen: 



