214 EXPERIMENT STATION RECORD. [Vol. 36 



Preliminary inve.stig.itions conducted at Rutgers College comparing field and 

 laboratory experiments in soil biology and using loam, silt loam, and sandy 

 soil are reported. 



It was found that "biological experiments (e. g., in ammonification) can be 

 successfully carried out in tlie field. As a rule, a greater amoiuit of organic 

 matter seems to be ammonified in the laboratory tests than in the field. Ni- 

 trogen fixation and nitrification studies in the field are greatly interfered with 

 by rains. The nitrogen content of the soil varies considerably, even over a 

 comparatively small area." 



Sources of error in soil bacteriological analysis, H. C. Lint and D. A. Cole- 

 man (Soil Sci., 2 {1916), No. 2, pp. 157-162, fig. 1). — Experiments conducted at 

 Rutgers College with sandy loam and clay loam soils, using dried blood as 

 organic matter, to determine the influence on ammonification of time and 

 method of mixing the soil with organic matter, are reported. 



It was found that mixing the organic matter with the soil for 30 seconds 

 showed a larger ammonia accumulation than where the mixing occupied only 

 15 seconds. The experimental error of the average for 30-second mixings was 

 smaller than that obtained for 1.5-second mixing periods. In general, there 

 was not so great a difference between the two periods of mixing with the 

 shaker as was the case where the spatula was used. The averages obtained 

 with the shaker were larger than where the spatula was used to stir the 

 organic matter into the soil. A comparison of the moist and the air-dry soil 

 showed a larger accumulation of ammonia in the case of the former soil. " In 

 general, the experimental error of the averages of the soils prepared in the 

 shaker is smaller than that obtained with the spatula, which bespeaks a nar- 

 rower variation in the duplicate determinations." 



A study of the action of carbon black and similar absorbing materials in 

 soils, J. J. Skinner and J. H. Beattie {Soil Sci., 2 (1916), No. 1, pp. 93-101, 

 pis. S). — It is pointed out that finely divided carbon is a good agent for physi- 

 ologically purifying distilled water and certain poor soil extracts, and that by 

 its absorptive qualities it improves the solution as a medium for plant growth. 

 A test made by mixing carbon black with poor soils failed to effect an improve- 

 ment, as the carbon, even though it might have had an absorptive action, would 

 itself be intermingled with the soil and be in contact with the plant roots. 



" With carbon incased in porous earthenware pots buried in soil, the growth 

 of grass, clover, and cowpeas was improved when growing in a poor unproduc- 

 tive soil in the greenhouse. On benches in the greenhouse a soil which con- 

 tained salicylic aldehyde and other organic compounds was improved for the 

 growth of string beans by the absorptive action of carbon buried in porous 

 tubes in the soil. In an experiment with string beans and lettuce in green- 

 house benches a soil made poor by the addition of salicylic aldehyde and vanil- 

 lin was improved in productivity by the action of carbon incased in porous 

 tubes. In a two years' field experiment carbon, charcoal, and chalk when put 

 in porous tubes and buried in the plats caused a good increase in growth of 

 cowpeas. 



" The beneficial action of carbon and other absorbents may be attributed to 

 its removing something from the soil solution which is harmful to plants. 

 The soil moisture passing through the carbon in its process of moving down- 

 ward and upward in the soil would be robbed of any such material. Soils 

 which contain soluble organic substances harmful to plants would be improved 

 for crop growth." 



Five references to literature bearing on the subject are appended. 



Soil fungi and their activities, S. A. Waksman (Soil Sci., 2 (1916), No. 2, 

 pp. 103-155, pis. 5). — Experiments conducted at the New Jersey Experiment 



