CKAPTEK XI 



MTlllFICATION AM) TIIK ('( »M !'( »SI TloN ol- 1H;A1N .\(.i; W \l M;s 



I. The Process of Nitrificalion. 



II. Dcnitrification. 



III. Nitrates in Cultivated Soils. 



lY. Nitrates in Manured and Cropped Soils. 



V. The Nitrates in Draina<re Waters. 



VI. Other Constituents of Drainaj^e Waters. 

 Referenees. 



I.- The Procs:ss of Nitrification. 

 The fact that cultivated soils conkl induce tlic coiivcrsinii 

 of organic matter containing nitrogen into nitrates li;i> Imch 

 known for a long time, indeed it was fur many years utilised on 

 a commercial scale for the production of nitre. Many of the 

 conditions under which nitrification takes place liad heeii 

 worked out by the men in charge of the old .salt pet i-e lieds 

 before Boussingault and other investigators consideretl ihem 

 afresh from the point of view of agriculture. Tlie pi'esence 

 of calcium carl)onate or some other base, tlie aeration nf tlie 

 soil, warmth, and a certain pi-oportion of watei- had l»eeii 

 shown to be necessary, while it was known tliai iinieli i»rM.inie 

 matter was injurious. Tli.it tlie action is brought about by a 

 living organism, was first established by the experiment- ..f 

 Schloesing and Miintz in 1877: and on the ajipraiMner «.f 

 their paper, Mr Warington, who was ili.n working in tlie 

 Rothamsted laboratory on the subject (.!' nitrates in llie soil, 

 proceeded to a further investigation of tlii> iiii|)<.iiant -nbjcct. 

 His first experiments eonfii-med the eonelusinns reached by 

 Schloesincr and Mimtz, and .showed that the amount of nitrates 



