052 EXPERIMENT STATION RECORD. 



shaking for one hour [was] in some cases not sufficient to separate the day from the 

 larger grains. No marked change appears intake place after6 hours' shaking, except 



in ease of samples shaken for 77 hours, all of which show an increased amounl of 

 clay, indicating that in samples shaken for long periods a breaking down of the soil 

 does occur to some extent. . . . 



"The use of ammonia in mechanical analysis increases the percentage of [the 

 finest] group in soils that ate not alkaline by destroying the formation of floccules 

 or aggregations of the smaller particles. In the case of strongly alkaline soils the 

 addition of ammonia appears to flocculate the soil rather than break up the floccu- 

 lations, and its use in such cases is therefore not desirable. From 5 to 10 drops of 

 ammonia added to 5 gin. of soil in 50 cc. of water appears to be sufficient to break 

 up the flocculations in nonalkaline soils. In case a soil contains a considerable 

 amount of lime or magnesium carbonate flocculation will occur, which usually 

 becomes more pronounced upon the addition of ammonia." 



Eight parallel analysesof the same soil which are reported show variations of from 

 10.9 to 12.5 per cent in loss on ignition, 2.3 to 3.2 in group (1), line gravel; 5.1 to 

 5.6 in group (2), coarse sand; 4.2 to 4.9 in group (3), medium sand; 12.6 to 14.4 in 

 group (4), fine sand; 7.2 to 8.8 in group (5), very fine sand; 15.1 to 17.6 in group 

 (6), silt; and 37.5 to 38.3 in group (7), clay. "These analyses may fairly he taken 

 to represent the limit of accuracy attainable by the centrifugal method under the 

 most favorable conditions." 



Other methods of mechanical soil analysis described include Hilgard's elutriator 

 method, Osborne's beaker method, King's aspirator method, and Voder's centrifugal 

 elutriator method (E. S. R., 16, p. 448). 



The physical improvement of soils, J. G. Mosier {Illinois Sta. Circ.82, i>/>. .'I, 

 figs. 4)- — This is a popular summary of information relating especially to soil 

 physics and management, and the value of organic matter. "It is preliminary to 

 more specific and technical bulletins which are to follow, giving the detailed results 

 of experiments and investigations relating to these subjects." 



Soils of Iowa, W. H. Stevenson (Iowa Ayr., 5 (1904), No. ■'>. pp. 1 55-159).— The 

 following distinct classes of soils which occur in Iowa are discussed: "(1) < reest, or 

 soils resulting from the decay of indurated rocks; (2) soils of fluviatile origin — allu- 

 vium, or stream-made soils; (3) soils of eolian origin — loess, or wind-made soils; (4) 

 soils of glacial origin— till, bowlder clay, drift, or ice-made soils." Of these the 

 eolian and glacial soils are by far the predominant classes. 



Soils, B. C. Aston (New Zealand Dept. Acjr. Rpt. 1904, pp. 135, 136).— Chemical 

 analyses and the reaction of samples of soils from different parts of Xew Zealand are 

 reported, the analyses being especially detailed in case of surface soils and subsoils 

 from the Momohaki Experimental Station. The soils are shown to be especially rich 

 in phosphoric acid and nitrogen, a considerable proportion of the phosphoric acid as 

 well as the potash being soluble in 1 per cent citric acid. 



Composition value of important types of Illinois soils based upon chemical 

 composition, J. A. Dewey (Illinois Agr., 8 (1903), No. 3, pp. 44-49). — A discussion 

 of this subject based mainly on Circular 68 of the Illinois Station (E. S. R., 15, p. 23). 



On the absorptive capacity of different layers of soils, K. S. Karpizov 

 (Pochvovyedenie [Pedologie], 6 (1904), No. 2, jrp. 137-151). — Four soils — chernozem, 

 clay, podzol clay, and sandy — were studied with regard to their capacity for absorb- 

 ing ammonia, phosphoric acid, and lime. Of each soil three consecutive layers w r ere 

 examined separately, the upper, the intermediate, and the subsoil. The absorptive 

 capacity was determined by the methods of Way and of Knop. The chemical and 

 mechanical composition of each soil was also determined. 



From the data presented the author arrives at the following conclusions: (1) The 

 absorption of ammonia, phosphoric acid, and lime decreased from the upper layer 

 downward in the main as the humus and the zoolites, which are the main factors 



