September 3, 1915] 



SCIENCE 



317 



Belation- of Lime to Production of Nitrates and 



Mineral Nitrogen: F. M. Scales. 



The lime requirement of an acid soil was deter- 

 mined by adding varying quantities of calcium car- 

 bonate to weighed portions of the soU, moistening 

 and, after am hour, testing with litmus paper until 

 a quantity was found that gave a neutral reaction. 

 The lime requirement by the Veitch method was 

 the same as the above. Fractions and multiples 

 of this requirement were added to 100 gm. portions 

 of soil which received in addition for one dupli- 

 cate set ammonium sulphate and for another dupli- 

 cate set alfalfa powder. They were moistened 

 with 18 per cent, of distilled water and incubated 

 for three weeks at 28° to 30° C. Determinations 

 of nitrate and mineral nitrogen present in the 

 samples showed that the nitrifying bacteria were 

 most active in the presence of 50 per cent, of the 

 calcium carbonate requirement and the ammonify- 

 ing and nitrifying groups combined in the presence 

 of 75 per cent, of the amount required according to 

 the chemical determinations. In this particular soil 

 an excess of calcium carbonate was markedly toxic 

 for the nitrifying organisms and not stimulating 

 for the ammonifiers. Some common crop plants 

 are to be grown on this and other soils containing 

 varying quantities of lime to determine what re- 

 lation exists between, the lime requirement for 

 optimum nitrification and for ammonification and 

 nitrification combined and that for the best growth 

 of the plants. 



A Soil Sampler for Soil Bacteriologists: H. A. 



Notes. 



The object of this sampler is to furnish a piece 

 of apparatus which will sample the soil under one 

 system of cultivation as well as under another. It 

 also becomes the container for the soil after the 

 sample is taken. 



The sampler is a brass tube 11 inches long, with 

 one end made into a cutting edge. This cutting 

 edge is so made that the soil is not appreciably 

 compacted when the sample is taken. The end hav- 

 ing the cutting edge is furnished with a tight- 

 fitting brass cap two inches in height. The open 

 end, plugged with absorbent cotton, makes the 

 sampler complete. The procedure in using this 

 apparatus follows: Plug and cap as many samplers 

 as you wish to take samples of soil; sterilize them 

 in the hot air sterilizer and take them to the field. 

 Remove a cap from a sampler, insert the driving 

 head above the cotton plug and drive the sampler 

 into the ground to the desired depth, pull it out, 

 flame and return the cap and the sample is ready 

 to take to the laboratory. 



The sampler has the following properties which 

 are important in bacteriological work: Easily ster- 

 ilized; easily kept clean; easily manipulated; du- 

 rable. 



The Effect of PJiosphates and Sulphates on Soil 



Bacteria: E. B. Feed. 



The influence of inorganic fertilizers on the bac- 

 terial processes of the soil has not received much 

 attention. For this reason a study of the effect of 

 some of the pure salts of those elements which con- 

 stitute an important part of commercial fertilizers 

 was undertaken. 



The aim was to determine, if possible, the 

 influence of phosphates and sulphates upon the 

 activities of soil bacteria and determine if the 

 fertilizing effect of these substances could be ex- 

 plained in part_ by the promotion of bacterial 

 action. 



The following methods were employed: 



Kate of ammonification in solution and in soil; 

 this was conducted with pure and with mixed cul- 

 tures of bacteria. Aside from this, determinations 

 were made of the relation of the number of cells 

 to the amount of nitrogen ammonified. To show 

 this relation, plate counts were used. The nitrogen 

 for ammonification was added to the solution in 

 the form of peptone and to soil in the form of 

 casein. The rate at which the nitrogen of these 

 substances is converted into ammonia, was deter- 

 mined by distilling with magnesium oxide. The 

 cultures were incubated at room temperature and 

 at different intervals the amount of ammonia de- 

 termined. 



Monobasic potassium phosphate in peptone solu- 

 tion caused a great increase in the production of 

 ammonia. This is noted with a pure-culture yel- 

 low ammonifier and with a suspension of soil bac- 

 teria. The gain was greatest at the end of the 

 first two days. 



Merck's precipitated calcium phosphate caused 

 a slight increase in ammonification, but not nearly 

 so large as the monobasic potassium phosphate. 



Sulphates of calcium and potassium increased 

 ammonification to a small extent. 



The action of monobasic potassium phosphate 

 was far greater than that of potassium sulphate. 

 From this it seems that the potassium ion does 

 not materially infiuenee ammonification. 



The results of plate counts show that monobasic 

 potassium phosphate causes an enormous increase 

 in multiplication of bacteria. This is followed by 

 a rise in ammonia. The ammonia production, how- 

 ever, is not in proportion to the number of bac- 



