620 EXPERIMENT STATION RECORD. 



On certain physical-chemical processes in the formation of soils, Rohland 

 (Landw. Jahrh., 36 {1!)07), xAo. 3, pp. J,73-'i83; ubs. in Chem. Zcntbl., 1907, II, 

 No. 0, p. 72Jt). — The author ascribes the colloids of the soil to the decomposi- 

 tion of feldspars by water and carbon dioxid. The colloids are flocculated by 

 the addition of an electrolyte, apparently dependent upon the simultaneous 

 separation of hydroxyl Ions from the alliali. The permeability of the soil de- 

 ponds upon this flocculation. Soils which contain colloidal hydroxids give off 

 or take up water at constant temperatures until the vapor tension of the col- 

 loids is in equilibrium with their surroundings, the water content varying con- 

 stantly with changes in temperature. The author lays great emphasis on the 

 importance of chemical and physical processes in the formation of soils. 



On the distribution of plant food in soil particles of different sizes, 

 PucHNER {Lamhc. Vers. Stat., 66 {1907), A'o. 6, pp. .'i63-Jf70; abs. in Chem. Ztg.. 

 31 (1907), No. 58, Report. No. 53, p. 350).— It was found that a diluvial coarse 

 sandy weathered gneiss soil was decidedly poorer in potash in its finer particles 

 than a tertiary compact weathered loam and a diluvial loess. The potash (and 

 also silica and soda) content as a rule decreased as the fineness of the particles 

 iucreased in all of the soils; on the other hand the content of aluminum, iron, 

 and manganese, as well as humus, increased with fineness of particles. No 

 uniform relation was observed in case of lime, nnignesia, and phosphoric acid. 



Influence of fallow culture on soil moisture, G. Nazakov (8elsk. Khos. i 

 Lyesov., 1905, No. 12; abs. in Zliur. Opuitn. Agron. [Russ. Jour. Expt. Landiv.], 

 8 (1907), No. 1, p. 82). — The author gives data gathered during 10 years on the 

 Poltava experiment field concerning the significance of fallow culture in rela- 

 tion to the accumulation of moisture in the soil. 



The experiments were conducted in a three-course rotation (fallow, winter 

 wheat or winter rye, and summer wheat) on plats 1,568 sq. ft. each. Samples 

 of soil wei'e taken at the following depths: (1) to 10 cm., (2) 10 to 25 cm., 

 (3) 25 to 40 cm., (4) 40 to 55 cm., (5) 55 to 70 cm., (6) 70 to 85 cm., (7) 85 to 

 100 cm., (8) 100 to 115 cm., (0) 115 to 130 cm., (10) 130 to 150 cm. The first 

 determinations of moisture were made at the time of the plowing of the black 

 fallow, the second at the time of the turning over of the April fallow, the third 

 at the time of plowing the May fallow, the fourth at the time of the turning 

 over of the June fallow, the fifth in the middle of July, and the sixth at the 

 time of the sowing of the winter cereal. The determinations of moisture were 

 made simultaneously on all the fallows. 



The mean data for 10 years show that in the winter all kinds of fallow have 

 the same moisture content. At the time of turning over of the April fallow the 

 moisture content of all the fallows except that of July was also the same, but 

 in the cultivated layer (0 to 25 cm.) the black fallow was more moist than the 

 others. At the time of the plowing of the May fallow the amount of water 

 within the entire depth under examination was the greatest in the April fallow, 

 followed in declining order by the black, the May and the June fallows. In 

 the cultivated layer the moisture was greatest in the black fallow. 



About the time of the turning over of the June fallow there was the most 

 moisture, both in the cultivated layer and throughout the remaining depth, in 

 the black fallow, which is due to the large pi-ecipitation during this month. 

 The determination of moisture in the second half of July showed a striking 

 preponderance in the April fallow over the black fallow, both throughout the 

 entire thickness of the layer under examination and in the cultivated horizon. 

 About the time of the sowing of the winter cereals the moisture in the to 10 

 cm. layer and also the 10 to 25 cm. layer was higher in the April fallow. In 

 all cases considered the May fallow was always more moist than the June 

 fallow. 



