756 



EXPERIMENT STATION RECORD. 



Another diagram shows "that there is in general quite a marked 

 agreement between the rate of nitrification and the degree of temper- 

 ature." 



Soil temperatures, W. S. Sweetser {Pennsylvania Sta. Ept. 1895, 

 j/p. 373-387, 320-349). — A record is given of tridaily observ^ations dur- 

 ing 1895 with thermometers at the surface and at depths of from 1 to 

 24 in. 



The following is a summary of observations during the growing 

 season : 



Soil temperatures, April to September, 1895. 



OrigiH, value, and reclamation of alkali lands, E. W. Hilgakd ( U. S. J)ept. Agr. 

 Yearbook 1895, pp. 10S-l:22,pl. 1, Jiffs. 5). — A discussion of the occurrence, characteris- 

 tics, and injurious effect of alkali soils; iufluence of irrigation on the movement of 

 alkali; composition of alkali salts; the utilization and reclamation of alkali lands; 

 and crops suitable for alkali lands. 



On the origin of liuniu.=, S. Bknni {Inaiuj. Diss. Giessen, 1896, pp. 32 ; Ztschr. 

 Naturw., 69, pp. 145-176; Bot. Centhl., 69 {1897), No. 2-3, p. 88; Chem. Centbl., 1897, 1, 

 No. 1, p. 31). ■ 



Humus in its relation to soil fertility, H. Snyder ( U. S. Bept. Agr. Yearbook 

 1895, pp. 131-142). — The nature and functions of humus are explained, and its influ- 

 ence on temperature, tilth, permeability, absorptive power, weight, and color, and on 

 water, nitrogen, phosphoric acid, and pota.sh contents of the soil is discussed. 



The influence of various moist soils on the gro^wth of plants, Perseke {Fiihling'a 

 landiv. Ztg., 46 {1897), No. 3, pp. 75-78). 



The exhaustion of an originally very fertile soil by a long-continued system 

 of soil robbery, M. Maercker {.Jalirl. agr. chem. Vers. Siat., Halle, 1895, pp. 79-86). — 

 An account is given of the system of farming without manure which has been prac- 

 ticed on the Oldenburg marsh soils since 1659, condensed from Zusammensetzung und 

 Diiiigerbediirfnis Oldenburger Marsclierden und deren Beivirtschaftung, M. Maercker. 

 Paul Parey, 1896. 



The effect of shading the soil {Scl. Avier., 76 (1897), No. 7, p. 101). 



Cultivation of heavy soils, T. Hoppenstedt {Die Kultur dcs schweren Bodeiis. 

 Berlin: Paul Parey, 1897). 



Reasons for cultivating the soil, M. Whitney ( U. S. Dept. Agr. Yearbook 1895, 

 pp. 123-130). — How water enters the soil is explained and the principles and eft'ects 

 on the water content of the soil of plowing, subsoiling, cultivating, uuderdraiuiug, 

 and irrigation are discussed, the whole being summed up in the statement that " tlie 

 object of all cultivation, in its broadest aspect is to maintain, under existing climatic 

 conditions, a uniform and adequate supply of M'ater and air in soils adapted to dif- 

 ferent classes of plants. This is the object alike of i)lowing, subsoiling, culMvation, 

 underdrainage, and irrigation; they are all processes to be used iu maintaining 

 suitable moisture conditions for the growth of crops." 



