WATER SOILS. 



633 



obtained were determined. The results are summarized in the following 

 table : 



Phosphoric acid and potash in humates produced i>i/ different materials. 



Phosphoric acid. 



In origi- 

 nal mate- 

 rials. 



In final 



product. 



Potash. 



In origi- 

 nal mate- 

 rials. 



In final 

 product. 



Cow-manure humus. 

 Green-clover humus 

 Meat-scraps humus - 



Sawdust humus 



Flour humus 



Oat-straw humus . . . 



Grams. 

 1.17 

 3.21 

 1.07 

 .85 

 .60 

 1.02 



Grams. 

 1.62 

 3.74 



1.18 

 .78 

 .71 



1.03 



Grams. 



1.06 



5.26 



.25 



.67 



.32 



2.42 



Grams. 

 1.27 

 4.93 



.36 



.70 



.48 



2.41 



This table shows that there is a wide difference in the power which 

 various humus-forming materials possess of forming humates with the 

 mineral matter of the soil. The nitrogenous materials appear to be 

 most active in this respect. There is also a great difference in the 

 readiness with which soils combine with the humus. 



Analyses of the humus of new and old soils are reported which show 

 that "in the long cultivated soil the hum us contains more carbon and 

 holds less nitrogen and mineral matter in chemical combination than in 

 the new soil." 



The influence of different methods of farming on the humus content 

 of the soil, the effect of forest fires, and the humus requirements of 

 soils are briefly discussed; and the average composition of the mineral 

 matter of the humus of a large number of samples of soils is reported. 



Production of ammonia at the expense of organic matter and 

 humus, E. Breal (Ann. Agron., 23(1897), Xo. 8, pjp. 356-369). — A series 

 of determinations of ammonia in plants and soils treated in different 

 ways are reported, which led to the following conclusions: 



(1) Ammonia is produced in soils and in plants in which growth has 

 been checked. A plant in vigorous growth does not produce ammonia. 



(2) Ammonia appears in the tissues of plants in a few hours if they 

 are deprived of air or treated with anaesthetics, such as ether or 

 chloroform . 



(3) Air-dry vegetable matter with a limited supply of air evolves 

 ammonia. 



(4) In the presence of water not only plant remains but such stable 

 nitrogenous substances as feathers, wool, horn, and leather give off 

 ammonia. 



(5) The humus of the soil also becomes a source of ammonia when it 

 is brought in contact with leaves in which fermentation has been set up 

 by a vegetable infusion. 



(6) A fragment of leaf not only produces ammonia in the soil, but it 

 is possible to measure the amount produced if the soil has previously 

 been sterilized. 



(7) Manure not only evolves ammonia itself, but also causes the pro- 

 duction of ammonia by the humus of the soil. 



(8) Plants absorb ammonia supplied to their roots. This is shown by 



