1920] SOILS — FERTTLIZERS. 42 Y 



out, this requiring longer In the heavy impervious soils than in the lighter ones. 

 It is considered advisable, therefore, in applying calcium cyanamid to soils, 

 to avoid any procedure which would tend to increase the formation of 

 dicyandiamid. such as spreading on freshly plowed land in the autumn or 

 top-dressing in the summer. On the other hand, soils containing considerable 

 hunuis are considered to be capable of absorbing dicyandiamid to such an 

 extent that the poisonous action gradually disappears. 



Aniinonium nitrate, L. ]Malpi:aux (Vic Ayr. et Ruralc, 9 {1920), No. 11, 

 pp. 29.'t-2V6). — The author briefly reviews the results of work by himself and 

 others on the use of ammonium nitrate as a fertilizer, and draws conclusions as 

 to its practical use. 



His experience demonstrated that the nitric nitrogen of ammonium nitrate 

 is as effective as that of sodium nitrate, and its ammoniacal nitrogen is as 

 effective as that of ammonium sulphate. With certain crops, such as beets, 

 it was found that the use of ammonium nitrate gave results similar to those 

 obtained when using a mixture of sodium nitrate and ammonium sulphate. 

 Ammonium nitrate had a regular and sufficiently prolonged action on crops, 

 and possessed the advantage of introducing no sodium into the soil. It is 

 notetl that the proper use of ammonium nitrate varies with the crop and the 

 soil. 



Relative efficiency of different carriers of nitrogenous materials, C. B. 

 Wir.i.iAMs (North Carolina Sta. Rpt. 1919, pp. 26. 27).— The average results of 

 field experiments by the station are said to show that with regard to relative 

 fertilizing value, the different common nitrogenous fertilizers stand in the 

 following order : Sodium nitrate, ammonium sulphate, calcium cyanamid, dried 

 blood, and cottonseed meal for cotton ; and sodium nitrate, ammonium sulphate, 

 calcium cyanamid, cottonseed meal, and dried blood for corn. 



The effect of leaching on the availability of rock phosphate to corn, 

 F. C. Bauer (Soil Set., 9 (1920), No. 4, PP- 285-251, figs. 4).— Investigations 

 conducted at the Wisconsin Experiment Station are reported, the primary 

 purpose of which was to test tlie effect of leaching on the availability of rock 

 phosphate. The experiments were conducted in the greenhouse, using corn 

 as the test crop. 



It was found that leaching the soil increased the availability of rock phos- 

 phate to corn by removing the excess of soluble cateium bicarbonate and other 

 soluble calcium salts. These results are in accord with the laws of mass 

 action and chemical equilibrium. Ammonium nitrate had a marked influence 

 on the solubility of rock phosphate to corn, due to its favorable effect on tlie 

 solubility of calcium bicarbonate and its capacity to produce an acid medium 

 either by acting as a physiologically acid salt or by becoming nitrified, but 

 sodium nitrate had no appreciable influence. The soluble calcium leached from 

 the pots treated with rock phosphate under the influence of sodium nitrate 

 and ammonium nitrate was found to be in the ratio of 1 : 2.9. The growth 

 ratio of corn under the same conditions was 1 : 2.5, showing, therefore, a 

 rather definite relation b'etween the calcium leached out in solution and plant 

 growth. Leaching caused a decrease in the production of dry matter where 

 acid phosphate was u.sed. Ammonium nitrate with acid phosphate appeared to 

 cause a physiological disturbance in the plants, especially with leaching. This 

 was probably due to the insufficiency of basic material. The phosphorus con-, 

 tent of the corn plants increased with increased growth. Leaching decreased 

 the calcium and increased the nitrogen content of the plants. It also in- 

 creased the water content as a result, undoubtedly, of the lessened concen- 

 tration of soluble salts in the soil medium. 



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