SOILS FERTILIZERS. 1017 



Report of the soil chemist and bacteriologist. .J. (i. Lipman and P. E. 

 Brown (Xcw Jirmy t<tus. Ri>t. r.)07, pp. lJ,l-.iOJ,, pis. .i).— This rei)ort eoutaius 

 accoimts of iuoculation experiuieiits with Azotobacter, bai-teriological studies of 

 an unproductive soil from Madison, X. J., and studies of the effect of soil treat- 

 ment on ammonification in culture solutions. 



Inoculation experiments icith Azotobaeter (pp. 141-170). — These experiments 

 were made in cylinders open at both ends, 4 ft. long, and suuk into the soil. 

 Prior to 1904 the soil in these cylinders (made up of equal parts of red shale 

 and quartz sand) had been subjected to various systems of manuring. In 1904 

 the soils were removed and thoroughly mixed, sampled for analysis, and re- 

 turned to the cylinders. The pots then received various manurial treatments 

 and one series was inoculated with A. rinclundii. another with A. beijrrincki. 

 and a third remained uninoculateil. The first summer the soils were left bare, 

 then a rotation of crops, including oats, corn, and rye, was grown in the pots in 

 close succession until 1907. 



The yield of dry matter and the nitrogen content of the crops were determined 

 in every cylinder. While considerable variations were observed in different 

 cases, it apiiears on the whole that inoculation with Azotobaeter did not in 

 these experiments increase the nitrogen resources of the soil, although the re- 

 sults do not preclude the possibility that inoculation with this organism may 

 be made of practical value. It will be necessary, however, to determine more 

 accurately the most suitable conditions for the growth of this organism. 



BaeterioJogirtil stutlir.s of Madison soil (pp. 170-186). — This soil, although in 

 good mechanical condition and abundantly supplied with lime and nitrogen, 

 was apparently in an abnormal bacteriological condition, since either the seetis 

 planted in it failed to germinate or the young plants quickly died. Plat experi- 

 ments in which the effect of adding acid phosphate, muriate of potash, and 

 carbon bisulphid was tested were made on the soil in place, and pot and culture 

 experiments were made in the greenhouse and laboratory of the station. Oats 

 were grown in the plat experiments and millet in the pot experiments. 



The results, particularly of the pot experiments, indicate that carbon bisulphid 

 improved the productive power of the soil. Acid phosphate was also beneficial. 

 Muriate of potash was of no advantage, and calcium carbonate produced a small 

 increase in yield. 



The culture experiments showed that the highest yield of ammonia nitrogen 

 was secured when the smallest amoimt of carbon bisulphid (2 gm. per pot) was 

 used. Acid phosphate also stimulated the growth of the ammonifying bacteria. 

 and the application of lime resulted in a progressive increase in ammonification. 



As regards the effect of the treatments on nitrifying power, the results were 

 irregular and inconclusive. The sum of ammonia, nitrite, and nitrate nitrogen 

 was considerably less than the amount of ammonia nitrogen originally present 

 in each culture, indicating either a volatilization of the ammonia from the 

 culture solutions or its transformation into soluble organic compounds. 



The soil treatments in general reduced the denitrifying power of the soils. 

 The double quantity of carbon bisulphid (4 gm. per pot) produced a more 

 marked eft'ect in this respiK-t than any other treatment. The application of 

 lime apparently increased the denitrifying [>ower of the soil. 



A considerable fixation of atmospheric nitrogen was observed in all cases in 

 culture solutions i!ioculate<l with the Madison soils, and this fixation was evi- 

 dently infiuencetl by the previous treatment of the soil. The double quantity of 

 carbon bisulphid proved su|ierior to any other treatment as a means of encour- 

 aging the activities of the Azotobaeter and other nitrogen-fixing species. 



