322 



Journal of Agricultural Research 



Vol. XV, No. 6 



into two portions, one of which was sealed in an air-tight jar. The other 

 was spread out and air-dried in the laboratory. Moisture was determined 

 in both the moist and the air-dry samples. Acidity was determined by the 

 Hopkins potassium-nitrate method,^ by the C. H. Jones calcium -acetate 

 method (4), and by the ethyl-acetate method (i). The results of these 

 determinations are given in Table II. In making the acidity determina- 

 tions, the moisture contents of the soils were taken into consideration so 

 that the proportions of dry soil to water and reagent used in making the 

 tests were the same for all samples of both wet and air-dry soils. 



Table I. — Analyses of soils used 



Determined." 



Volatile matter 



Potassium oxid (KjO) 



Calcium oxid (CaO) 



Magnesium oxid (MgO) 



Manganese oxid (Mn304) 



Ferric oxid (Fe^Oj) 



Aluminium oxid (AUOa) 



Phosphorus oxid (P265) 



Sulphate (SO3) 



Residue 



Nitrogen 



Humus (acid) *> 



Humus c 



Hygroscopic moisture 



Acidity: 



Potassium-nitrate method <i . lb 

 Calcium-acetate method <i . Ah 



Water-holding capacity « 



Per cent. 



3- 57 

 .27 

 . 18 

 .40 

 .08 

 3.68 

 4.68 



•OS 



. 12 



87.76 



.07 



•73 



.70 



1.50 



5.460 



5.875 

 48.6 



B. 



Per cent. 



3-92 



•25 



•17 



.24 



.04 



1.28 



2.80 



.06 



. 10 



92-57 



. 12 



1-31 

 I. 17 

 1.30 



2, 220 



4,875 

 48.7 



Per cent. 



7-45 

 .40 



•37 

 .61 



•17 



3- 04 



4-57 



•15 



. 16 



83.42 



. 22 

 2. 25 



3- 13 

 1.84 



460 



8,125 



55- I 



Per cent. 

 10. 13 

 . 21 

 . 10 

 •23 

 .04 

 I. 04 



3-09 



. 10 



. II 



85-50 



Per cent. 

 85.20 



• 17 

 .46 

 . 20 

 . 02 

 .48 

 •85 



• 13 

 •31 



12.31 



.40 

 5-72 

 4.96 

 I. 90 



2, 520 



10, 625 



67. I 



2. 04 



50- 19 



52. 00 



8.38 



5,080 

 69, 750 



200. O 



o Wiley, H. W., ed. official and provisional methods of analysis, associ.^tion of oFFicLiU, agri- 

 cultural CHEMISTS AS COMPILED BY THE COMMITTEE ON REVISION OF METHODS. U. S. Dept. Agr. BUT. 

 Chem. Bui. 107 (rev.), 272 p., 13 fig. 1908. Reprinted, 1912. 



b Ammonia soluble without previous washing with dilute hydrochloric acid. 



c Washed with hydrochloric acid, digested with ammonia, filtered, and refiltered till clear. 



^ Pounds of calcium carbonate required to neutralize 2,000,000 pounds of soil. 



e Water-holding capacity in grams of water per 100 gm. of dry soil. 



In studying the results given in Table II, the following rather striking 

 points are noted : 



In each soil the degree of acidity, as indicated by all the methods used, 

 was greater when the soil was held at one-half water-holding capacity 

 than when it was held at one-fourth water-holding capacity. 



All the soils which had been carried at one-half water-holding capacity 

 were more acid than they were at the beginning of the experiment. This 

 is in accord with the results obtained by Noyes and Yoder (5). 



The soils high in organic matter gave greater acidity when held at full 

 water capacity than when kept one-half saturated with water. The soils 

 low in organic matter gave a lower degree of acidity when kept at full 

 water than when kept at one-half water-holding capacity. 



' WiLEV, H. W., ed. OP. CIT. 



