RECENT WORK IN AGRICULTURAL SCIENCE. 



CHEMISTRY. 



Methods of chemical soil investigation, G. Berju {Landw. Vers. Stat, 55 {1901), 

 No. 1-2, 2U>- 19-31; abs. in Chcm. Centbl., 1901, I, No. 14, p. 795).— Treatment with 

 hydrochloric acid is claimed to give no indication of the available plant food in soil. 

 Dyer's method using 1 liter of 1 per cent citric acid for 100 gm. of soil is considered 

 preferable to using i liter of 2 per cent acid for the same amount of soil, because 

 absori)tion by the soil is less from the weaker solution than from the stronger. In 

 experiments on the length of digestion required, it was found that sliaking in a rotary 

 apparatus making 48 revolutions per minute for 6 liours one day and 2 hours the 

 following day was sufficient to extract the soluble potash and lime in every case and 

 the phosphoric acid in most cases. In these experiments 750 cc. of 1 per cent citric 

 acid at a temperature of 18 to 20° C. was used to 75 gm. of soil. Somewhat less was 

 dissolved by 8 hours continuous shaking than by the above method. Longer shaking 

 dissolved a little more phosphoric acid, but the slowly soluble phosphoric acid is not 

 considered practically important. Samples of sandy and loam soils were shaken 

 with 0.1 per cent solutions of potassium nitrate and ammonium chlorid, with and 

 without the addition of 1 per cent citric acid solution. The absorptive power of the 

 soils for potash and ammonia was only very slightly affected l)y the citric acid. The 

 influence of the absorptive power of soils on the results of chemical analysis is to be 

 further studied. 



On the methods of chemical investigation of soils, B. Sjollema {Cliem. Zfg., 

 25 {1901), No. 29, pp. 311, 312). — Experiments are reported in which samples of soil 

 of different character were subjected to successive extractions with 1 per cent citric 

 acid. The results show that ordinary methods, such as that of Dyer, do not remove 

 all of the phosphoric acid soluble in 1 jjer cent citric acid, but that on subseiiuent 

 treatment with this solvent further amounts of this constituent go into solution, the 

 amounts so dissolved being quite large, but varying with the character of the soil. 



On the determination of the potash content of soils, A. Rumplek {Lmulw. 

 Vers. Stat., 55 {1901), p. 149; abs. in Chem. Ztg., 25 {1901), No. 18, liepert., p. 62).— 

 A preliminary note on the determination of the potash extracted from soils by treat- 

 ment with limewater or solutions of potassium chlorid. There seems to be a definite 

 limit to the extraction of the potash by this method, beyond which further treatment 

 with the solvent fails to remove any more of this constituent. The author believes 

 that the potash removed by the proposed treatment is tliat occurring in zeolitic sili- 

 cates and is especially available to plants. Vegetation experiments to further study 

 this subject are to be undertaken. 



Analysis of soils, J. A. Mukray {Analyst, 26 {1901), No. 301, pp. 92-96; abs. in 

 Jour. Chem. Soc. ILondon], SO {1901), No. 463, II, p. 350). — A criticism of the method 

 proposed by Hall and others (E. S. R., 12, p. 905). The principal suggestions offered 

 are that (1) the constituents should be reported in ounces per cubic foot; (2) a deter- 

 mination should be made of organic carbon; (3) that undried soils yield a larger pro- 

 portion of available phosjihoric acid than dried; and (4) the stones in the soil should 



be tested for available plant food. 



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