SOILS. 



33 



Some notes concerning the nitrogen content of soils and humus, 

 E. Fulmer ( Washington tita. Bui. 23, pp. 19). — Investigations relating 

 to the importance of humus in the soil are briefly reviewed, and analy- 

 ses showing humus, total nitrogen, nitrogen in humus, total phosphoric 

 acid, phosphoric acid in humus, potash, lime, iron oxid, and organic 

 matter are reported for 53 samples of soil from the following counties: 

 Spokane, Jefferson, San Juan, Okanogan, Whitman, Whatcom, Kitsap, 

 Skagit, Yakima, King, Thurston, Snohomish, Island, Clallam, Clarke, 

 and Pierce. 



"Hilgard's conclusion that any soil in which the humus contains less than 2.5 per 

 cent of nitrogen is to he suspected of ' nitrogen hungriness ' seems to be fully verified 

 by Tthe author's] results. 



"The very great difference found by Hilgard and Jaffa between the percentages 

 of humic nitrogen in arid soils, and in soils of humid regions, is not fully confirmed 

 by this work, although the samples of arid soils tested were too few to warrant any 

 conclusion." 



The attempt is made to trace the relationship between the total nitro- 

 gen and the nitrogen in the humus, but a comparison of actual deter- 

 minations of nitrogen with the calculated amounts does not show very 

 concordant results. 



On the improvement of retentive clays: Drainage of the 

 so-called "hardpan" lands of southern Illinois, B. Davenport 

 (Illinois Sta. Bui. 40, pp. ,357-362). — It is claimed that the soil of south- 

 ern and southwestern Illinois is largely the resultant of the action of 

 two great glaciers, the first of which left a deposit of " impalpable clay 

 and sand through which water makes its way so slowly that it is classed 

 as an impervious soilj" the second " in its descent covered deeply with 

 a mixture of bowlder clay, sand, and gravel the older and thinner de- 

 posit . . . left by the first glacier." The heavy and retentive subsoil is 

 known in this region as hardpan, and w r hen it comes to the surface it 

 constitutes a " scald" or "stick spot." ^Notwithstanding their unfa- 

 vorable physical condition, these soils are very fertile. 



Mechanical analyses of 2 samples of these soils and of 1 sample from 

 the station for comparative purposes are given in the following table: 



Mechanical analyses of ignited soil. 



1 Organic matter equals loss on ignition of water-free soil. 



