May 4, 1906.] 



SCIENCE. 



711 



tion, has very kindly sent me samples from a 

 number of the plots of the five years' rotation 

 experiments at Wooster, Ohio, where fertil- 

 izing experiments on limed and unlimed land 

 are being conducted. The fertilizing experi- 

 ments were begun in 1894, while the lime ex- 

 periments were begun with the corn crop of 

 1900, each of the five series of plots being 

 given 2,000 pounds per acre of lime (CaO) 

 as it was prepared for corn. 



The lime was applied to the plowed ground 

 and harrowed in before planting corn, and 

 the plots were again plowed before the sowing 

 of clover which was sowed in the wheat and 

 timothy a year later. 



The reaction of a number of the plots, with 

 other data, is given in the following table: 



double those by the regular sodium chlorid 

 method with this soil. 



The results here submitted have consid- 

 erable interest. Bearing in mind the difficulty 

 of securing representative soil samples, re- 

 membering that the method will not give re- 

 sults closer than fifty parts per million, it is 

 still quite evident that several of the fertil- 

 izers have had considerable effect on the reac- 

 tion of the soil. This is most evident on the 

 plots that have received large quantities of 

 sodium nitrate alone, or with other materials. 

 In these cases the natural acidity of the un- 

 limed plots has been materially reduced. 

 Smaller applications of nitrate with full rations 

 of acid phosphate and of muriate of potash 

 have had no apparent effect. Potassium 



No difference could be detected in the reac- 

 tion of water extracts of these soils; all were 

 practically neutral. 



For comparison, results by a modification 

 of the sodium chlorid method^ are also given. 

 The modified method consists of treating 20 

 grams of the soil with 200 c.c. of N/5 neutral 

 sodium chlorid solution in a Jena flask, allow- 

 ing it to stand over night, filtering, boiling to 

 one half volume and titrating with N/10 al- 

 kali. The results by this procedure are about 



= Bull. No. 73 Bureau of Chemistry, U. S. Dept. 

 of Agr. 



chlorid has not increased the apparent acidity 

 despite the fact that the residue left by the 

 salt is an acid, and the further fact that by 

 double decomposition and absorption such 

 salts give rise to acid reacting salts. Manure 

 too has been without effect. Acid phosphate 

 has, as it should when properly made, slightly 

 reduced acidity. Practically the same story 

 is told by the sodium chlorid results, plots 5 

 and 29 showing considerable reduction in 

 acidity. An interesting point here is that 

 although enough soda and lime have been 

 applied to these plots to make them alkaline 



