1916] SOILS FERTILIZERS. 213 



for the process of diffusion, the proportions would be very different from 

 what they are." 



High proportions of carbon dioxid and frequently low proportions of oxygen 

 were found in the neighborhood of the roots of such crops as hemp, indigo, 

 and maize, together with small but definite quantities of hydrogen, " Although 

 high proportions of carbon dioxid are frequently present in the gas as extracted 

 from the soil, calculation shows that considerably the greater part is present in 

 the dissolved state in the soil solution." 



Determination of the ratios of oxygen and nitrogen to argon in the soil 

 gases showed " that the chief changes in the soil have to do with the oxygen, 

 whilst nitrogen-assimilation or nitrogen-evolution in dry land is at least so 

 limited that it is usually difficult to detect. ... In cases like the gas from 

 rice land, the argon determination demonstrates with certainty that most 

 of the nitrogen is derived from the soil and manure. . . . 



" It is certain that diffusion of gases through soils at a depth of from 12 

 to 15 in. is so efficient as to warrant the conclusion that cultivation of the 

 surface soil is unnecessary for purposes of aeration. The well-established 

 value of good cultivation must be referred to other causes." 



Agronomic and soil conditions in the Selby smoke zone, C. F. Shaw and 

 E. E. Free (U. S. Dept. Int., Bur. Mines Bui. 98 {1915), pp. 451-462). — An inves- 

 tigation of the agronomic and soil conditions of the Selby smoke zone in 

 Solano County, CaL, to determine the extent to which the vegetation is in- 

 jured and the soil polluted by smelter fumes and dust in that district, is 

 reported. 



The opinion is expressed that while crop yields in the region are below 

 what would be expected for such a climate, they may be attributed more to 

 poor soil and poor agricultural practice than to some definite unfavorable 

 factor such as smelter dust and fumes. With reference to soil pollution, it 

 is concluded that " arsenic is certainly a normal, though extremely minute, 

 constituent of the soils of the region, and lead is probably so. The past con- 

 tamination of the soils by lead and arsenic from the smelter is possible but 

 unproved and appears not to be susceptible of proof. The quantities of lead 

 and arsenic added, if any, have been small and of the same order as the 

 quantities of these elements normally present in the soils. The maximum 

 amounts of lead and arsenic found ai'e far too small to have any injurious 

 effect on plants grown in the soils. Much larger amounts than those actually 

 found would be without practical effect on the agriculture of the region," 



Data regarding soil samples are included. 



Mississippi: Its geology, geography, soils, and mineral resources, E. N. 

 Lowe {Miss. Geol. Survey Bui. 12 {1915), pp. 335, pi. 1, figs. 2S).— This is a pop- 

 ular report covering the geology, geography, mineral resources, underground 

 waters, and soils of the State of Mississippi. The section on soils has been 

 taken mainly from a previous report (E. S, R., 26, p. 811). 



Soil survey of Johnson County, Missouri, B. W. Tillman and C. E. Deae- 

 DOEJT {U. S. Dept. Agr., Advance Sheets Field Operations Bur. Soils, 1914, pp. 

 S3, fig. 1, map 1). — This survey, made in cooperation with the Missouri Experi- 

 ment Station and issued May 5, 1916, deals with the soils of an area of .531,840 

 acres in western IMissouri, lying in the residual prairie section of the Great 

 Plains region. The topography is rather more rolling than undulating and 

 level. The county is well drained. The soils are classed as upland soils of 

 residual origin, which cover about 85 per cent of the area, and lowland soils of 

 alluvial origin. Sixteen soil types of 10 series are mapped, of which the 



