424 EXPEBIMENT STATION KECOKD. 



The results varied witli the different compounds, but all exerted a stimulat- 

 ing effect in the lower concentrations and a toxic action in the higher. " Meas- 

 ured in terms of their influence upon ammonification and nitrification as it 

 takes place in soil, the toxicity of lead arsenate is the least. Next come zinc 

 arsenite and arsenic trisulphid. The greatest toxicity is exerted by Paris 

 green." The stimulation was greatest with lead arsenate and least with Paris 

 green. 



It is concluded in general that water-soluble arsenic may exist in such soils 

 " to the extent of 82 parts per million without entirely stopping ammonification 

 and nitrification. Large quantities of ammonia and nitric nitrogen may be pro- 

 duced in a soil containing 50 parts per million of water-soluble arsenic." It 

 is thought improbable that lead arsenate, zinc arsenite, or arsenic trisulphid 

 " will ever be applied to agricultural soil in quantities sufficient to become in- 

 jurious to soil bacteria. Paris green may, but the quantity added would have 

 to be large." 



Some factors influencing ammonification and nitrification in soils. — I, 

 Influence of arsenic, J. E. Greaves {Ce^itU. Bakt. [etc.], 2. AM., 39 (1913), 

 No. 20-22, pp. 5^-560; abs. in Jour. Chem. Soc. [Lo7idon], 106 (1914), No. 616, 

 I, pp. 236, 237). — The work described in this article has been noted from other 

 sources above. 



Cupric treatments and the nitrification of the soil, G. Pattjrel (Prog. Agr. 

 et Vit. (Ed. VEst-Centre), 34 {1913), No. 23, pp. 711-714; ais. in Internat. Inst. 

 Agr. [Rome'\, Mo. Bui. Agr. Intel, and Plant Diseases, 4 {1913), No. 8, pp. 

 1187, 1188). — A study was made of the rate of nitrification in soils of vineyards 

 which had been sprayed with varying amounts of copper salts for the preven- 

 tion of disease. 



The general conclusion was that there is no reason to apprehend injurious 

 results as regards nitrification from the frequent use of such copper sprays. 

 Even in soils containing over 2 per cent of copper salts the nitric nitrogen was 

 still 60 per cent of that in untreated soil, and with 0.1 per cent of copper sul- 

 phate the nitric nitrogen rose to 90 per cent of that in untreated soil. Copper 

 salts added to the soil were rapidly converted into insoluble form, and for this 

 reason exerted only a weak inhibitive action on nitrification even when large 

 quantities were used. 



Nitrification in acid humus soils, A. Petit {Ann. Sci. Agron., 4- ser., 2 

 (1913), II, No. 4, pp. 397, 398). — The author reports finding pronounced evi- 

 dences of nitrification in a decidedly acid forest soil deficient in lime. 



The relation between decomposition of cellulose and the nitrogen economy 

 of nature, II, H. Pringsheim {Mitt. Deut. Landw. GeselL, 28 {1913), No. 20, 

 pp. 295, 296). — This is a second paper on this subject (E. S. R., 28, p. 720), and 

 deals briefly with aerobic and anaerobic nitrogen-fixing bacteria, nitrogen fixa- 

 tion in the presence of nitrates, nitrogen loss and gain with thermophile bac- 

 teria, and notes on pure cultures of cellulose bacteria. 



Nitrogen accumulation in continuous rye culture, P. Ehrenberg {FUhling's 

 Landw. Ztg., 62 {1913), No. 13, pp. 450-462) .—T\ie author calls attention to a 

 field which is said to have produced a slightly increasing crop of rye for many 

 years, with little or no nitrogen fertilization. He explains this on the ground that 

 the nitrogen required for the rye crop was absorbed as ammonia by the soil from 

 the local rainfall, which is said to contain quantities of ammonia combinations, 

 originating from the combustion of large amounts of poor grade coal in the 

 neighborhood. 



Nitrogen accumulation in continuous rye culture, F. Lohnis {FUhling's 

 Landiv. Ztg., 62 {1913), No. 23, pp. 838-841) '— The author questions whether the 



