1048 EXPERIMENT STATION RECORD. 



The effect of plant growth and of manures upon the retention of bases by 

 the soil, A. D. Hall and N. H. J. Miller ( Proc. Hoy. Soc. [London], Ser. B, 77 

 (1905), No. B514, pp. 1-32, figs. 2; abs. in Jour. ('hem. Soc. [London'], 90 (1906), No. 

 520, LI, pp. 119, 120). — The investigations reported in this article deal " with the 

 changes in the amount of calcium carbonate, the chief substance in the soil acting as 

 a base, which are brought about by natural agencies, by manuring, and particularly 

 by the growth of plants." 



It is stated that the Rothamsted soils generally contain about 3 per cent of calcium 

 carbonate, due mainly to former applications of chalk. "Determinations made in 

 numerous samples fr.om different plats of Broadbalk, Agdell, and Hoos fields, taken 

 at different dates from 1856 to the present time, show that the soils of the unma- 

 nured plats lose in drainage on the average about 1,000 lbs. of calcium carbonate per 

 acre per annum. This agrees closely with results derived from analyses of field 

 drainage by Creydt, von Seelhorst, and Wilms [E. S. R., 13, p. 723; 16, p. 856]. 



"The loss of calcium carbonate is increased when ammonium salts are employed 

 by an amount equivalent to the acid of the manure. Sodium nitrate and farmyard 

 manure diminish the loss. 



"Analyses of wheat plants grown in water culture and of the solutions themselves 

 showed that the plants take up an excess of acid from the salts supplied, leaving 

 behind a corresponding excess of base. This explains how it is that, despite losses 

 by nitrification, soils which contain only minute amounts of calcium carbonate 

 (examples of such soils are given) are able to maintain a neutral condition. The 

 experiments also furnished evidence that the roots of the plants did not excrete any 

 organic acid or other organic matter. 



"Finally it is shown that calcium oxalate and other organic salts are converted 

 into carbonate by soil organisms." 



Investigations on changes in the nitrogen of soils, F. Lohnis (Mitt. Landw. 

 Inst. Leipzig, 1905, No. 7, pp. 1-105; Centbl. Bali, [etc.], 2. AbL, 15 (1905), Nos. 12, 

 pp. 361-365; 13-14, pp. 430-435; abs. in Jour. Chem. Soc. [London], 88 (1905), No. 

 518, LI, p. 854; 90 (1906), No. 519, LL, p. 46).— The investigations here reported were 

 made on soil of a plat on the Oberholz experimental field of the agricultural institute 

 of the University of Leipzig during 1903 and 1904. 



Oats were grown on the plat in 1903, and after these were harvested half of the 

 area was given shallow cultivation while the other was left in stubble. In 1904 the 

 field was planted in potatoes, which received applications of the various fertilizers 

 (bone meal, lime nitrogen, urea, ammonium sulphate, sodium nitrate, etc.), the 

 transformations of which it was the purpose of the experiments to study, namely, 

 the formation of ammonia from bone meal, lime nitrogen, and urea; the formation 

 of nitrate from ammonium sulphate; the liberation of nitrogen from nitrate, and the 

 fixation of nitrogen by bacteria. The influence of the time of year(temperature), 

 weather, and of various methods of culture on the yields and utilization of the nitro- 

 gen of the different fertilizers was also studied, and the different kinds of bacteria 

 which took part in the transformation of the nitrogen were isolated and determined. 



Decomposition was least affected by the season of the year in case of bone meal 

 and most in case of urea and calcium cyanamid. The nitrogen of calcium cyanamid 

 was quickly converted into ammonia during April and May, and its effect on the 

 crop was similar to that of ammonium salts. It was found that Bacillus mycoides 

 converted 39 per cent and Bacterium vulgare 28 per cent of the total nitrogen of bone 

 into ammonia in 3 weeks. Allowing the soil to remain in stubble had a distinct 

 effect on denitrification and nitrogen assimilation, but not on the other changes. 



The chief effect of bringing the lower layers of the soil to the surface was to dimin- 

 ish nitrification, the least effect being observed in the case of decomposition of bone 

 meal and urea, while there was no effect as regards nitrogen assimilafi6n and decom- 

 position of calcium cyanamid. Dry weather in July was especially injurious as 



