SOILS FERTILIZERS. 919 



[Effect of soluble salts in the soil on the growth of sugar cane], J. P.. 

 IlAKKisoN ( West IiHlian Bill., 9 (1008), Xo. I, pp. ID-Sl ; ahs. in Jntcnidt. t^iigur 

 Jour., 10 (1908), Xo. 118, pp. 500-509; Chcm. Ztg., 32 (1908), No. 87, Repert., 

 p. 55}). — The author discusses, on the basis of exiieriments extending over a 

 nuuiber of years, the effects of lonR-contiuued applieatious of sulphate of am- 

 monia and nitrate of soda on the productiveness of the soil, the effects of culti- 

 vation and of manures on the composition of the soil waters of the sugar cane 

 fields, the relation l>et\veen temporary and permanent alkalinity of soil waters, 

 the proportion of nitrogen in troi)ical soil waters, and the concentration of the 

 subsoil water. 



The general reaction of the fertile heavy clay soils of British Guiana is 

 slightly alkaline, and a decided and comparatively rapid Increase of the alkaline 

 salts in the soils under experiment was observed. This concentration of salts 

 exerts a decidedly injurious effect on the physical proi)erties of the soil and on 

 the growth of cane, but promotes the activity of nitrifying organisms. The 

 alkalinity of the soil may explain why sulphate of ammonia gives better I'esults 

 than nitrate of soda when applied in large amounts. The I'emedies suggested 

 by the author's exiieriments are deep drainage and the application of gypsum, 

 calcium phosphates, and other neutralizing materials. 



The isolation of harmful org'anic substances from soils, O. Schreiner 

 and E. C. Shouey (U. S. Drpt. Agr., Bur. Soils Bid. 53, pp. 53, pis. .',). — This 

 bulletin presents briefly the evidence of the occurrence of harmful substances in 

 the soil, reviews previous attem]its to isolate the toxic comjiounds. and rei»orts 

 investigations relating to the isolation and toxic properties of a number of 

 organic bodies, products of the decomposition of organic matter of vegetable 

 and animal origin, in unproductive soils. 



The isolation of four well-defined crystalline bodies is reported. The first 

 of these, picolin carboxylic acid (E. S. R., 19, p. 419), possesses faint acid 

 properties and also has the power of acting as a base toward strong acids. 

 In exi)eriments with wheat stHnllings it was found to be harmful in concen- 

 trations of 300 parts i)er million, but like many poisons had a stimulating 

 effect when present in small quantities. 



A second body, dihydroxystearic acid, isolated from unproductive soils 

 (E. S. R., 20, p. 701) " was injurious in all concentrations tested and ulti- 

 mately caused death of the plants in concentrations of 100 parts i)er million." 



The two other crystalline bodies isolated were agrosterol and agroceric 

 acid (E. S. R., 20. p. 509). " Neither of these substances appears to be harmful 

 to wheat and [they] are of interest in the study of soil fertility chiefly with 

 regard to their possible conniption with the generation or destruction of 

 injurious or l>eneficial comi)ounds. although it is not impossible that they 

 may be themselves harmful to plants other than that tested." 



The nitrogen problem, R. I'ebotti (Hot. Quind. Soc. Agr. Ital., 13 (1908), 

 Vo. 23. pp. 1 18(1-1 19(!; 1.', (1909), Nos. 2, pp. ^8-62; 3, pp. S.'/-/00).— This is a 

 L'<'neral discussion of the natural ])rocesses by which the soil acquires or loses 

 nitrogen. Tender the head of gain of nitrogen, bacteria, molds and alga\ and 

 legumes are considered, and under loss volatilization of ammonia and denitrifi- 

 'Mtion are briefly treated. 



I'ractical methods of promoting th<> natural processes of increasing and 

 • ■unserving the nitrogen supjily of the soil are also discussed. 



Leguminous plants as fixers of the nitrogen of the air, M. Passon (Bol. 

 Inst. Agron. [Ftdo Paulo], 1 (1908), N<k 10, pp. 3.',5-S',9, fig. /),— Data are given 

 for yields and nitrogen content of velvet bean, cowpea. and jjcannt. showing 

 the amounts of nitrogen accumulated by crops of the.se plants. 



