SOILS FEETILIZEKS. 621 



" In the natural soil in the field, however, the loss was greater, due to the 

 presence of considerable gravel and sand. From 20 in. of irrigation more than 

 one-third penetrated below 6 ft. The proportions were less where the appli- 

 cations were smaller. 



" The rate of penetration In uniform sandy loam soil was about 5 ft. in from 

 15 to 20 days, it being more rapid during the first few days following irrigation 

 and slower toward the end of the period. The more sandy and gravelly the soil 

 the more rapid was the penetration. . . . 



" The amount of water lost from the surface of an open tank is proportional 

 to the amount of surface exposed. Protection from wind reduces the loss 

 slightly. Also, the higher the temperature and the lower the humidity the 

 greater is the evaporation loss, but these are factors over which we have no 

 control." 



Data are also reported as to the duty of water on wheat, corn, and soy beans. 



The fixation of nitrogen in Colorado soils, W. P. Headden {Colorado Sta. 

 Bui. 186, pp. S-Jfl). — This bulletin contfiins data supplementing that previously 

 reported (E. S. R.. 25. p. 814), but dealing more particularly with the question 

 of the origin and distribution of the nitrates occurring in excessive amounts in 

 so-called niter spots in certain Colorado soils. The author asserts that ordinary 

 Colorado soils " are not unusually rich in nitrogen. They are only moderately 

 well supplied with it and the unusual amounts of nitrates found [in the niter 

 spots] can not be produced by the nitrification of the supply already in the soil, 

 but this supply must be supplemented by nitrogen from some other source." 

 He is of the opinion " that this other source is the atmosphere." He believes 

 that the nitric-nitrogen is not derived from the same sources as the ordinary 

 white alkali and its high ratio of the nitric to total nitrogen in many of the 

 soils, particularly in the surface portion of the niter spots, is "due to fixation 

 and nitrification." 



The deeper portions of the soil in these spots " are usually poor in nitrates but 

 irrigation or rainfall may carry the nitrates on the surface downward, even 

 into the ground water. While the solutions of potassic and sodic nitrates show 

 capillary action, it is doubtful whether the calcic and magnesic nitrates do not 

 move downward, especially in soils that are quite moist, rather than upward. 

 The calcic and magnesic nitrates do not show capillary movement, exposed in 

 glass vessels, as do sodic chlorid and nitrate, ammonic chlorid, and many other 

 salts. 



" The solubility of the nitrates contributes to their easy and rapid removal by 

 downward moving waters. The soil seems to have but little or no power to 

 retain these salts, nitrates, so they pass readily into the drainage waters of the 

 country, but the ground and drainage waters are rich in nitrates only when they 

 come from niter areas. . . . 



" The shales and sandstone do not furnish these nitrates or else all of the 

 well waters would be rich in nitrates, but they are not richer in nitrates than 

 well waters usually are. These well waters, both from ordinary and artesian 

 wells, are usually quite rich in the so-called alkali salts, but not in nitrates." 

 Moreover, the niter spots occur in sections where " shales and sandstones do not 

 occur, and consequently can not be derived from them. ... If the alkalis and 

 nitrates have a common origin they should have a common distribution, but this 

 is not the case even for very limited areas. If they owed their origin to leach- 

 ing then the ground waters found beneath these lands should contain notable 

 quantities of nitrates, but this is not true and the nitrates are localized in the 

 brown spots." 



A study of nitrification in certain types of Virginia soil, E. B. Feed {Vir- 

 ginia Sta. Rpts. 1911-12, pp. 174-201, figs. 3). — A. study was made of the rate of 



