502 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



well-kn<nvn "alkali bri(ljj:e" wliicli was introduced by this Bureau 

 has been remodeled and a much improved instrument is now available 

 for field and laboratory work. The general lines of investigation 

 have been continued, but among the special results of the year's 

 work attenti(Mi may be calleil to tlie following: 



Certain soils from southern China, in tlie Province of Fukien, 

 which are famous for the production of a liigh-grade tea, were exam- 

 ined. These soils do not simulate very closely any of the types yet 

 encountered in this country, their nearest f)r()totypes in this country 

 being the Cecil and Durham soils of the southern riedmont and cer- 

 tain soils in Oklahoma. Althougli these Chinese soils are reported to 

 have been under clean cultivation for tliousands of years and witliout 

 fertilization, both mineralogical and chemical examination showed 

 that they had a content of the so-called essential plant-food elements 

 decidedly higher than the average American soil, and the examination 

 of them has a considerable value as affecting correct ideas of soil 

 fertility. Further light on the general problem, showing the wide 

 distribution of mmeral elements in the soil, is afforded by another of 

 the Bureau's investigations of the past 3^ear, in which it was shown 

 that the element barium is to be found in nearly all soils from every 

 part of the United States, but appears to be especially abundant in 

 the feldspar grains of certain soils in the Great Plains areas. The 

 phosphates of lime which may be expected in the soils of all parts of 

 the country and have an especial interest as fertilizers have been 

 further studied and important information gained regarding the 

 nature of the phosphates which can exist under different conditions. 

 At the same time, in collaboration with the United States Geological 

 Survey and the Land Office, the phosphate deposits of Utah, Idaho, 

 Wyoming, and Florida have been investigated and important results 

 obtained regarding their nature and importance as a future source of 

 supply for American agriculture. Especial attention is being given to 

 the utilization of the lower grade material, which under present mix- 

 ing methods is largely wasted. The fixation of atmospheric nitrogen 

 in form suitable for use as a fertilizer has been studied with a view to 

 determining the possibiUty of other methods of manufacture than 

 those now in commercial use. It appears that a number of methods 

 are theoretically possible, but all involve practical difficulties, the 

 most important or which is a cheap source of power. The color of 

 soils has been studied, and it has been shown that most soils can be 

 readily classified in this respect and that color has not only consider- 

 able theoretical importance in determining tlie origin and methods of 

 formation of the soil, but is generally of practical importance as indi- 

 cating the character of physical and chemical conditions determining 

 the crop ada])tations or the soil. It is very well known that lime 

 greatly affects the solubility of the organic substances in the soil. 

 Though not so w^ell known, it is nevertheless true that conversely 

 the solubility of the lime is greatly affected by organic matter, as 

 established by some investigations the Bureau has been conducting. 

 More important, perhaps, has been the determination of the chemical 

 nature or the solid substances formed. The phenomena of ffocculation 

 and sedimentation are still under investigation, not only because of 

 their importance in soil transport and deposition, but also because of 

 the relation to the important problems of soils crumbing and tilth. 



