268 



the drainage liquid, as it flowed away, were contained 0.8 to 0.9 mg. of nitro- 

 gen in the form of ammonia and between 19. i to 27.1 mg. of nitrogen in the 

 form of saltpetre. The liquid sewage used for the irrigation contained 24.9 

 mg. ammonia nitrogen and 0.9 mg. saltpetre. A comparison of these figures 

 shows that the fertilizing nitrogen introduced in the form of ammonia is 

 oxidized almost entirely to nitric acid by bacterial action during its filtering 

 through the soil. Way's investigations^ show that, on an average, no very 

 large amounts of mineral elements may be detected in drain water. He 

 found in 1000 parts only 0.003 parts of potassium, 0.186 of calcium, 0.138 

 of sulfuric acid, 0.002 of phosphoric acid, etc. Nevertheless we should not 

 forget that continued reductions are involved which are added to one an- 

 other, in case there is abundant drainage. 



A comprehensive summary of lysimeter experiments in Rothamsted, 

 which covered 35 years, and more recent investigations in Holland- show 

 how rapidly, as a rule, the nitrification of the fertilizers, such as the ammonia 

 salts, takes place of itself. Even in the fall and winter the nitrification is so 

 active, that great nitrogen losses may be expected. On this account it is ad- 

 visable to use ammonia salts as a top fertilising in the spring. 



When using sulfates and chlorids of ammonia, the calcium combined 

 with the sulfuric and hydrochloric acids is washed away in large quantities 

 in the drain water. This process is necessarily preliminary to the combi- 

 nation of the ammonia in the soil and the subsequent nitrification. H the 

 calcium carbonate does not suffice for this conversion, the ammonia salts 

 easily become dangerous for the plants. Since the sulfates and chlorids of 

 potassium, like those of ammonium, form gypsum and calcium chlorid, which 

 are not absorbed by the soil, the necessity of a periodic I'nning is evident. 



B. The Work of the Soil Organisms. 



The activity of animal life in relation to the changes in the soil is men- 

 tioned in the third volume of this work. In this is concerned primarily the 

 work of the soil bacteria, the agricultural significance of which has been 

 shown in a Very comprehensive short summary by Behrens^ and Hiltner*. 



According to the chief work performed by the bacteria, we could speak 

 of those which set free the nitrogen and others which attack the carbon 

 compounds (as, for example, the pectin and cellulose ferments) and finally 

 those forming humus and those decomposing it. But not only the action of 

 these organisms on their substratum is of importance here, but, especially, 

 their influence on each other. Some genera or species disintegrate one an- 

 other, others nourish each other. 



1 Further analyses by A. Mayer, Agrikulturchemie. 5th. Edition, 1902, Vol. 2, 

 Section I, p. 118. 



2 Beleuchtung- der Bodennitriflkation durch Drainwas-seruntersuchungen. Mit- 

 teil. d. D. I.andn-. Ges. lOOfi, Stiick 13. 



3 Behrens, Die durch Bakterien hervorgerufenen Vorgange im Boden und Diin- 

 ger. Arb. d. Deutsch. Landwirtsch.-Ges. 1901, Part 64. 



4 Hiltner, L., Ueber neuere Erfahrungen und Probleme auf dem Gebiete der 

 Bodenbakteriologie etc. Arb. d. Deutsch. Landwirtsch.-Ges. 1904, Part 98. 



