514 EXPERIMENT STATION BECOBD. [Vol.38 



are very permeable. The nitrogen content varies within wide limits. The 

 phosphoric acid content originates only from tlie organic matter content, and 

 it is shown that the nitrogen and phosphoric acid increase in the same propor- 

 tions. The calcareous sands are poor in potash, while the black and gravelly 

 soils contain the most potash. 



" The percentage of available elements in these soils is very low. Apart from 

 the alluvial soils of the ' Gorges ' of Black River, the i-est contains but traces 

 of phosphoric acid. ... In every place where calcareous sand is in large pro- 

 portion, only traces of available potash are found. On the other hand, in some 

 black soils and other uncultivated ones comparatively high percentages are met 

 with, and these percentages are well above those of the cultivated soils." 



Soil survey.— II, Grand Port {Dept. Agr. Mauritius, Soil Circ. 2 (1916), 

 [English Ed.l, pp. 3, pi. 1). — This survey (Part 1 of Section II) reports physi- 

 cal and chemical analyses of samples of the soils of lands forming a natural 

 valley between the Creole Mountain on the east and the highlands east of 

 Riviere Eau Bleue on the west in the Island of Mauritius. 



The nitrogen content is considered normal, but available phosphoric acid is 

 present only in traces. The potash content is low. 



Soil flora studies, I-V, H. J. Conn {Jour. Bad., 2 {1911), Nos. 1, pp. 35-45; 

 2, pp. iS7-i54).— The substance of this article has been abstracted from an- 

 other source (E. S. R., 37, pp. 516, 517). 



The recent work at Rothamsted on the partial sterilization of soil, E. J. 

 Russell {Interiiat. Inst. Agr. [Rome], Internat. Rev. Sci. and Pract. Agr., 8 

 {1917), No. 5, pp. 613-681). — This is a general review of the work on partial 

 sterilization of soil at the station, most of which has been noted from time to 

 time. 



Treatment of peat beds to prevent loss of nitrogen by bacterial action, 

 T, Abnd {Landw. Jahrb., 49 {1916), No. 2, pp. 191-213; abs. in Chem. Zentbl, 

 1916, II, p. 231; Internat. Inst. Agr, [Rome], Internat. Rev. Sci. and Pract. 

 Agr., 7 {1916), No. 10, pp. UU, 1415; Chem. Abs., 11 {1911), No. 10, p. 1513).— 

 Experiments conducted at the Bremen station for peat investigations are re- 

 ported to determine whether denitrification and the decomposition of nitrates 

 in peat beds can be prevented. Two methods were used: "(1) Soil conditions 

 were made such as to encourage nitrification and processes favorable to plant 

 growth; and (2) the reduction of nitrates was inhibited by the use of germi- 

 cides. By the first method denitrifying organisms alone were affected, while by 

 the second method the destruction of both denitrifiers and nitrate reducers was 

 involved." 



The soil used in the first method was from a well-rotted peat bed, crumbly 

 and rich in bacteria and containing fair quantities of ammonia, traces of 

 nitrates, but no nitrites. " The sample was put through the 3-mm. sieve and 

 mixed with pure calcium carbonate at the rate of 0.3 gm. of carbonate to 40 

 gm. of soil (these proportions having previously been shown to produce maxi- 

 mum nitrogen losses). The soil was watered to bring it up to its original 

 water content and placed in glass vessels in layers 0.8 cm., 3 cm., and 9 cm. 

 thick ; 0.5 gm. of dry nitrate was added to each vessel, which was then plugged 

 with cotton wool and incubated for a fortnight at 28° C. . . . 



" The results showed conclusively that denitrification varies with the depth 

 of the soil layer in the vessels, 1. e., with the amount of oxidation which can 

 take place. . . . The mean total losses of nitrogen for the three layers (9 cm., 

 3 cm., and 0.8 cm.) were 17.8 mg., 2.1 mg., and 3.8 mg., respectively. Where 

 the soil was very loosely packed no denitrification took place, but in other 



