19171 SOILS FERTILIZERS. 213 



The idea of determining the percentage of total lime requirement satisfied is 

 offered as a means of comparing the condition of basicity of different soils and 

 as an aid in the solution of other soil problems. The limited amount of experi- 

 mental data available indicates that there may be some relation between the 

 percentage of total lime requirement satisfied and the reaction of the soil to litmus, 

 carbonates being practically absent. Crop yields in pot experiments have not 

 indicated that an application of precipitated calcium carbonate, according to the 

 indications of the vacuum method, which is considered to represent saturation 

 with calcium, is harmful in other than exceptional cases." 



Four references to literatui'e bearing on the subject are appended. 



The effect of some acids and alkalis on soil bacteria in the soil solution, 

 O. M. Geuzit (Sotl SoL, 3 {1917), No. S, pp. 289-295, figs. 2).— This is an ab- 

 stract of a thesis, in which experiments conducted at the Michigan Agri- 

 cultural College on solutions extracted from rich, sandy loam and sandy soils 

 are reported. 



" The solutions were adjusted to various degrees of reaction with N/100 

 sodium hydroxid and hydrochloric acid, methyl red being used as an indicator 

 for titration, and 10-cc. quantities were placed in 100 gm. of pure sterile quartz 

 sand. The moisture content of the cultures was adjusted about every ten days. 

 The counts of bacteria in the soil solution were made upon sodium asparaginate 

 agar after seven days of incubation at a temperature varying between 19 and 

 23° C." 



It was foand that " the development of the general flora of the soil bacteria 

 from sand and sandy loam soils, when studied in the soil solution of sand cul- 

 tures, was retarded if the reaction of the medium had a higher OH-ion con- 

 centration than N/1,000. The development of soil bacteria was inhibited when 

 the reaction of the medium became neutral. The H-iou concentration of N/1,200 

 hydrochloric and sulphuric acids was germicidal to about 99.2 per cent of soil 

 bacteria. . . . With H-ion concentration of N/2,164 the rate of multipli- 

 cation of soil bacteria from sandy loam corresponded to the rate of destruction 

 so that there was no change in the total number of bacteria. The H-ion con- 

 centration of N/2.S40 inhibited the growth of 43 per cent of soil bacteria when 

 compared with the growth of soil bacteria in the medium with N/412 OH-ion 

 concentration. The reaction of alkaline culture.s was gradually neutralized and 

 later became acid. When the ' toxic limit ' of acids toward Indian corn seed- 

 lings was compared with the toxic limit of about the same concentration of the 

 game acids on the general flora of the soil bacteria from sand and sandy loam 

 soils, the soil bacteria were injured to the extent of 43 per cent." 



Twenty references to literature bearing on the subject are appended. 



A review of investigations in soil protozoa and soil sterilization, N. Kope- 

 LOFF and D. A. Coleman (Soil Sci., 3 (1917). No. 3, pp. 197-269) .—This paper 

 is intended to be a survey of the subject to date and includes a list of 337 

 references to literature bearing on the subject. 



The ecological significance of soil aeration, W. A. Cannon and E. E. Fbee 

 (Science, n. ser., 45 (1917), No. 1156, pp. 178-lSO). — Experiments conducted by 

 the Carnegie Institution of Washington and Johns Hopkins University are re- 

 ported, which show " that different species of plants may differ markedly in 

 their response to variations in the composition of the soil atmosphere, and hence 

 to changes in soil aeration. The effects of diminution of oxygen are manifest 

 and the results with Opuntia indicate a direct and specific effect of carbon 

 dioxid In addition to the effect of the dilution of the oxygen." 



It is pointed out that " although deficiency in aeration has frequently been 

 suggested as an agricultural diflSculty, or as the reason why certain species do 

 not grow upon soils of heavy texture, it does not appear that this suggestion 



