SOILS FERTILIZERS. 123 



" No evidence could be brought out that the wheat-plant roots drew more 

 heavily on the water-soluble nitrates in one 6-iu. soil layer than in any other 

 at any time. ... 



" The corn plants at the end of their most active season of growth had re- 

 duced the amounts of water-soluble nitrates in the soil to the same degree of 

 exhaustion as had the wheat plants in the corresponding period of their de- 

 velopment. . . . 



" The wheat and corn plants reduced the nitrates to a constant amount — 

 about 15 parts per million in the dry soil. The wheat removed the moisture 

 aLso to a fairly constant degree, namely, about 15 per cent. 



•• Denitrification, as measured by the nitrites found, could not account for the 

 changes occurring in the nitrate content in the soil layers. 



" No correlation could be established between the amounts of nitrates and 

 the air temperature or between the nitrates and the soil moisture. 



" Translocation of the nitrates by rain could not account for the seasonal 

 changes in the amoimts of nitrates in the different soil layers. 



"The general increase and decrease in water-soluble nitrates followed the 

 same course in the fallow plat and in the cropped plats, the only general differ- 

 ence being that there were more nitrates in the fallow plat after May 16 than 

 in the wheat plat." 



Denitrification in soils and liquids, A. Koch and H. Pettit {Centbl. Bakt. 

 [etc.], 2. Aht., 26 {1910), No. 10-12, pp. 335-345).— The authors claim that de- 

 nitrification in soils progresses differently from that in liquids, depending upon 

 the nature of the bacteria and the physical condition of the medium in which 

 they are situated. In liquids and very wet soils from which oxygen is ex- 

 cluded, the bacteria take their oxygen from the nitrates present in the soil and 

 thus liberate nitrogen, but in well aerated soils this does not occur, as the 

 bacteria can then use the oxygen of the air. These denitrifying bacteria 

 remain practically quiescent in soils with a. water content below 25 per cent, 

 but when the water reaches 25 to 30 per cent or more they become suddenly 

 active and liberate considerable quantities of nitrogen. 



Fertilizing- effect of soil sterilization, B. Dyer {Nature [London], 83 (1910), 

 No. 2108, p. 9(i). — Attention is called to the practice followed by large growers 

 of vegetables under glass near London of partially sterilizing their soil by 

 means of steam as giving results on a large scale confirming the conclusions of 

 Russell and Hutchinson regarding the influence of soil sterilization (E. S. R., 

 22, p. 121). 



The fertilizing influence of sunlight, A. and G. L. C. Howard (Nature 

 [London], 82 (1910), No. 2103, pp. 456, ^57).— The beneficial effects of the 

 practice followed in some parts of India of exposing the soils to the intense 

 heat and light of the hot weather of April and May are also explained on the 

 basis of the investigations of Russell and Hutchinson referred to above. 



The fertilizing influence of sunlight, E. J. Russell (Nature [London], 83 

 (1910), No. 2105, pp. 6, 7). — Commenting upon the article noted above, the 

 author suggests the desirability of further investigations to determine to what 

 extent exposure to strong sunlight will bring about partial stei'ilization and 

 increased productiveness of the soil. 



The fertilizing influence of sunlight, J. Aitken (Nature [London], 83 

 (1910), No. 2106, p. .J7 ) .—Referring to work by Russell and others, noted 

 above, the author calls attention to an instance of increasetl productiveness 

 following the heating of the surface soil by a large and long-continued fire. 



The action of carbon bisulphid on soils and its use in vineyards, F. INIuth 

 (i^cparnte from Mitt. Dent. Weinbau Ver. Mains, 1909, pp. 22; abs. in Centbl. 

 48507°— No. 2—10 3 



