KITROGBNOUS ORGANIC MAITEIIS OF THE SOIL. 275 



great part, but a small proportion of it being in the form 

 of ammonia-salts or nitrates. 



In 1846, Krocker, in Liebig's laboratory, first estimated 

 the nitrogen in a number of soils and marls {An?i. Ch. ic. 

 PA., 58, 387). Ten soils, which were of a clayey or loamy 

 character, yielded from 0.11 to 0.14 per cent; three sands 

 gave from 0.025 to 0.074 per cent; seven marls contained 

 0.004 to 0.083 per cent. 



Numerous examinations have since been made by An- 

 derson, Liebig, Kitthausen, Wolff, and others, with simi- 

 lar results. 



In all but his latest writings, Liebig has regarded thi\ 

 nitrogen as available to vegetation, and in fact designated 

 it as ammonia. Way, Wolff, and others, have made evi- 

 dent that a large portion of it exists in organic combina- 

 tion. Boussingault [Agronomie, T. I) has investigated 

 the subject most fully, and has shown that in rich and 

 highly manured soils nitrogen accumulates in considerable 

 quantity, but exists for the most part in an insoluble and 

 inert form. In the garden of Liebfrauenberg, which had 

 been heavily manured for centuries, but 4°!^, of the total 

 nitrogen existed as ammonia-salts and nitrates. The soil 

 itself contained — 



Total nitrogen, 0.2G1 per cent. 

 Ammonia, 0.0022 " " 



Nitric acid, 0.00034 " " 



The subjoined Table includes the results of Boussin- 

 gault's examinations of a number of soils from France and 

 South America, in which are given the quantities of am- 

 monia, of nitric acid, expressed as nitrate of potash, and 

 of nitrogen in organic combination. These quantities are 

 stated both in 2)er cent of the air-dry soil, and in lbs. av. 

 per acre, taken to the depth of 17 inches. In another 

 column is also given the ratio of nitrogen to carbon in the 

 organic matters. [Agfrononiie, T IT, pp. 14-21.) 



