SOILS FERTILIZERS. 817 



r;nrf;ice watcM" for iniiratlon is limitoil, ami it lias t)een found that irrigation 

 iiloii.u the main valley of the KeiMihlifan in the western eonnties is practicable 

 only near the headwaters and below the months of some of the sti'ong tributary 

 streams. "The counties inclndinj; most of the area are Dimdy, 17,41.'j acres; 

 Hitchcock, 13,070; Redwillow, 3,035. In 1904 the area was much less." 



Agriculture is stated to be by far the most important resource of the region, 

 but is greatly affected by local variations in climate, ground water, and soils. 

 " The many different kinds of soils have not been differentiated. In general, 

 the distribution of the different types corresponds with that of the geologic 

 formations, but minor variations exist, often of considerable importance in 

 phmt growth. There are in the regi<m three fairly distinct agricultural prov- 

 inces — the loess table-lands, the alluvial bottom lands, and the sand hills. 



" The loess plains of the wide table-lands between the valleys occupy the 

 greater part of the area treated in this report. Where the streams have cut 

 through the loess, the various iinderlyiug formations appear with soils of dif- 

 ferent kinds extending in narrow belts along the valley slojjes. Glacial soils, 

 which occur mostly in .lefferson County, are clayey or sandy, with an admixture 

 of pebbles and bowlders. Soils on or below outcroi)s of Dakota sandstone are 

 sandy, but in places are clayey or ocherous. Extensive alluvial soils occur along 

 the rivers and their tributaries. They contain a high percentage of silt or sand 

 and usually a small proportion of clay. Soils formed from the cretaceous shales 

 and chalk rock extend along some of the valley slopes not covered by loess or 

 alluvium, and are usually of bad quality for agriculture. 



" In the sand-hill region loose sandy soil of the dunes consists mainly of 

 quartz sand with but little clay, while in the basins and dry valleys there is 

 an iidmixtnre of some humus and considerable clay. 



" The table-land soil is sandy, and may grade into sand hills on one side and 

 into the so-called plains marl or western loess on the other. The talus slopes 

 below ledges of tertiary rock are mostly sandy or gravel ly."" 



Dew ponds {Jour. Bd. Agr. [London], 1', {IU07), Xo. 8, pi). .'/US, Ji99). — This 

 is a notice of a second edition of a book by A. J. and Li. Hubbard on Neolithic 

 Dew iionds and Cattleways (E. S. R., 17, p. 533). 



A contribution to the study of the location of underground water, L. Rey 

 (Jour. A(jr. J'rat., n. .ser., 1-i ( 1907), No. 4i, PP- 567-570). — The external features 

 indicating the presence of underground waters are described. 



Relation between radioactivity of underground waters and their hydrology, 

 I". Diem:ut and E. Bouquet {C'onnit. liciul. Acad. /Sc/. [7'«r/.sJ, l.'i5 (1907), No. 

 Ui, pp. 89-',-896, fig. I ; abs. in Rev. Sci. [Paris], 5. ser., 8 (]907),No. 22. p. 701).— 

 A study of the radioactivity of various si)ring waters showed variations in this 

 property corresponding with changes in level of the ground water and in elec- 

 trical resistance. The radioactivity was especially marked in the upper levels 

 of the water and varied at different depths. No differences corresponding to 

 geological and paleontological conditions were observed. 



SOILS— FERTILIZERS. 



Soils, C. W. r.ruKKTT (Ac/r York and London, 1907, pp. A 11+303, pi. 1, figs. 

 129). — The book treats in a popular way of the pro|)erties, improvement, and 

 management of soils and the problems of crop growing and feeding. Different 

 chapters deal with soil makers, the soils that living things have made, what we 

 find in soils, the texture of the soil, how plants feed, the elements that plants 

 use, how plant food is preserved, getting accpiainted with plant food, the jmten- 

 tial plant food — its stores and nature, the role the tillage l)lays, liming the land — • 



