SOILS — FERTILIZERS. 29 



a matter of the size of the individual interspaces of the soil, not of their total 

 amount. (3) Soil Water and the Plant. — A very important but much neglected 

 factor in the movement of water from soil to plant and through the plant is the 

 evaporating power of the air. (4) Physical Constants of the Soil. — ^A critical 

 examination of the various measurements which have been proposed as charac- 

 teristic soil constants shows that all are in some degree unsatisfactoiy. The 

 mechanical analysis in particular, is much less adequate than is usually be- 

 lieved. It is probable that another and better constant can be developed out of 

 the water equivalent and the critical moisture content. (5) Soil Tempera- 

 tures. — The main effect of the soil character upon its temperature is due to its 

 water capacity. The wetter soil warms and. cools more slowly." 



A counting method for the mechanical analysis of soils, C. C. Fletcher 

 (Science, n. ser., SJf {1911). Xo. 876', 2>p. -'i95, .'i96). — The method is described as 

 follows : 



"A definite amount of soil is weighed out, put in a sterilizer bottle with water 

 and ammoni.i. and shaken in a mechanical shaker for at least seven hours. 

 With most soils i gm. of material and 120 cc. water give a good dilution for 

 accurate counting. A compound microscope with a micrometer eyepiece and a 

 counting plate are necessary. In the micrometer used one scale division corre- 

 sponds to 0.005 mm., the superior limit of the clay, and ten divisions to 0.05 mm., 

 the superior limit of the silt. The counting plate is marked off in squares of 

 0.1 mm. a side. After removing from the mechanical shaker, the contents of 

 the bottle are thoroughly shaken by hand and a sample for examination 

 immediately taken from the center of the bottle. A drop is placed on the 

 counting plate and the number of silt and clay particles in ten squares counted. 

 The sand need not be considered. In most cases it settles quickly and escapes 

 being taken in the subsample. If a sand particle appears in the subsample it 

 is disregarded." 



A factor must be used in obtaining a ratio to express the relative total 

 weights of silt and clay in the soil. " In 26 soils of widely varying texture 

 lately analyzed by the counting method, and checked by the centrifugal analysis, 

 an average of the factors was 35. The factors varied, however, widely enough 

 to preclude using this method as a regular routine analysis for all soils. 

 ... It should be used only where time is especially important or the facilities 

 are not available for the determination of silt and clay " by centrifuging and 

 evaporating. 



Composition of some Massachusetts soils, J. B. Lindsey (Massachusetts 

 Sta. Rpt. 1910, 'pt. 1, pp. 339-348) .—Ana\yses of 13 carefully selected typical 

 soils of Massachusetts as well as of a large number of miscellaneous samples 

 taken from cultivated fields in different ])arts of the State are reported. Com- 

 paring the analyses of the typical soils with the ordinary standards indicates 

 that none of the soils is highly productive but that most of them would prob- 

 ably be capable of producing satisfactory ci'ops. The analyses of the miscel- 

 laneous samples indicate that most of them can at least be classed as normal 

 from a chemical standpoint, some of them good, and a few rich. 



The soils of the Armidale district and of Tenterfield, H. I. Jensen (Agr. 

 Gaz. K. S. Wales, 22 (1911), No. S, pp. 699-711, map /).— The author reports 

 the results of analyses of soils surrounding Armidale and Tenterfield, New 

 South Wales, and discusses them in relation to their geology and crop adap- 

 tation. 



The Tenterfield soils are typical blue granite, and are low in phosphoric acid 

 and nitrogen and satisfactory as regards potash. 



The soils of the Armidale district are classified as granite, alluvial, slate and 

 sandstone, and basalt. The granite soils are derived mainly from biotitic and 



