SOILS — FERTILIZERS. 417 



deposit. The plowing under of straw and green crops is also said to be of much 

 value. 



The radio-active content of certain Minnesota soils, J. C. Sanderson (Amer. 

 Jour. ScL, 4. ser., 39 {1915), No. 232, pp. 391-391, fig. 1 ) .—Reference is made to 

 previous work by the author (E. S. R., 25, p. 718) and others bearing on the 

 subject, and experiments to determine the interde[)endence, if any, existing 

 between the radio-active content and fertility of 13 Minnesota soils are reported. 

 The apparatus and method of procedure used in determining the radium content 

 of a soil are also described. 



Without exception, the very fertile soils were found to be richer in radium 

 and thorium emanations than soils of inferior fertility, which it is stated is in 

 accord with the results of experiments on artificial enrichment of soils. " The 

 conclusion seems justifiable that the hygroscopic properties of a soil are a valu- 

 able index of its fertility . . . because the presence of moisture increases the 

 radio-active emanating power of the soil and . . . the ability to retain moisture 

 implies fineness of texture, which also means great emanating power, so that at 

 least part of the effect is due to a greater proportion of ' free ' radium and 

 thorium emanations." 



A report on the Piedmont soils, particularly with reference to their nature, 

 plant food requirements, and adaptability to different crops, C. B. Williams 

 ET AL. (Bnh N. C. Dept. Agr., 36 {1915), No. 2, pp. 122. figs, i^).— This report 

 deals briefly with the origin, topography, and drainage of the soils of the Pied- 

 mont section of North Carolina and more fully with the soil material, soil 

 types, chemical composition of the soils, and field tests of the fertilizer require- 

 ments of certain of the prevailing types. 



This section, including about 38 per cent of the State or 11,814,700 acres of 

 land, embraces a wide belt running in a northeast and southwest direction 

 across the central part of the State. The topography is dominantly rolling 

 and uneven. The soils are all of residual origin and with the exception of a 

 few local areas have good natural surface drainage. It is stated that the soils 

 of the region are adapted to a wide range of crops, including field, truck, and 

 fruit crops. 



"While there is considerable variation, all the Piedmont soils have been 

 found to be fairly high in potash, low in phosphoric acid, and to contain a 

 fair amount of lime. The amount of nitrogen is usually very small. ... In 

 most of the Piedmont soils there is sufficient potash in the surface soil to pro- 

 duce maximum crops for a hundred years or more, while twenty to twenty-five 

 such crops would entirely exhaust the phosphoric acid. ... As a general 

 thing crops like corn, cotton, and wheat are not generally benefited by appli- 

 cations of potash, but phosphoric acid first and nitrogen second, except with 

 the Iredell loam where it is first, are the controlling constituents in increasing 

 yields. In the use of fertilizers for the production of profitable crops or for 

 the improvement of the soil, liberal applications of phosphates must be made, 

 and nitrogen must also be supplied either in fertilizers or from soil-improving 

 crops. Lime has not materially increased the yields of cereals and seed cotton, 

 but has seemed to prove beneficial in most cases with the legumes grown on 

 soils of this section to which lime has not been added in recent years." 



Crop rotations are considered necessary in the management of these soils 

 to build up a permanent system of fertility and three, four, five, and six-year 

 rotations are outlined. 



Moisture relation of Texas soils, G. S. Feaps {Jour. Amer. Soc. Agron., 7 

 {1915), No. 1. pp. 31-33). — Three years' percolation experiments in galvanized 

 iron cans with 4 clays and clay loams and 4 sands and sandy loams, each 

 being subjected to six different treatments, brought out the fact that the clays 



