ATMOSPHERIC NITROGEN IN THE SOIL 305 



point by Voorhees and L,ipman. 6T The experiments conducted were 

 so arranged as to bring out the relation of leguminous crops, 

 such as cow peas, to soil and nitrogen and to determine, as far 

 as practicable, the value of this leguminous crop as a source of 

 nitrogen to subsequent non-leguminous crops. The soils selected 

 contained an abundance of phosphoric acid and potash. The 

 facts established by the investigation are of practical importance, 

 in respect of the possibility of accumulating nitrogen in the soil 

 directly from atmospheric nitrogen. The greater number of the 

 investigations were of negative value, but a sufficient positive gain 

 was found in some cases to indicate that further investigation may 

 develop methods to promote the fixation of nitrogen in the soil. 

 The authors admit that the probability of the continued fixation 

 of nitrogen, in the manner in which the investigations were made, 

 is not very great. Attention is called to the fact, however, that 

 the present knowledge of bacteriological conditions in the soil is 

 still so limited, that a general and successful inoculation with 

 non-symbiotic nitrogen-fixing bacteria is out of the question. 

 There is also a danger to be avoided in the attempt to increase 

 the soil nitrogen by means of the inoculation of leguminous plants, 

 where large quantities of leguminous material are incorporated 

 in the soil, as shown by researches above mentioned. The nitro- 

 gen-decomposing bacteria can develop freely and the denitrifying 

 organisms may set free more nitrogen than the nitrifying organ- 

 isms fix. 



Therefore, the practical problem of the utilization of atmos- 

 pheric nitrogen as a fertilizing material is to be considered, and 

 the conditions which determine the comparative rate of nitrifi- 

 cation and denitrification are to be carefully studied in order that 

 valuable results may be reached. 



The authors also found that even under carefully controlled 

 conditions there was no uniform gain of nitrogen due to the 

 inoculation of soils with nitrifying ferments. 08 



The investigation shows that there was no decided gain in 

 nitrogen in the inoculated soil after the inoculation. There was, 



67 Journal of the American Chemical Society, 1905, 27 : 556. 



68 New Jersey State Agricultural Experiment Station, 25th Annual Re- 

 port, 1904 : 239. 



