434 EXPERIMKNT STATIuN RECORD. 



per cent of nitrifying organisms were found in tlie first 6 in. of soil and none were 

 found below 2 ft. it is evident that the nitrates found at a greater depth .had leached 

 down from near the surface. The largest amount of nitrates was found in a plat on 

 which wheat had followed peas, but "on July 14 the field on which corn had been 

 grown the {)receding year contained 39 per cent more nitrates than for the continuous 

 wheat field. On July 30 the difference was even more marked, Ijeing 61 per cent more 

 of nitrates." Large amounts were also found ii bare fallow, l)ut small amounts under 

 jjrairie sod. 



"The continuous growing of wheat, or other grains, or cultivated crop, rapidly 

 depletes the organic matter from the second 6 in. of soil. The growing of clover and 

 peas in a crop rotation causes a marked increase in the organic matter and humus 

 in the soil in both the first and second 6 in. . . . Plowing under a green crop does 

 not ijroduce as beneficial results as come from plowing grass lands. Plowing under 

 a green crop leaves the organic matter in a mass and not uniformly distributed 

 throughout the soil. After grass in a crop rotation the soil shows a large increase in 

 amount of organic matter, but less than two-thirds as much as is found in adjoining 

 fields of native prairie soil. . . . 



"Soils on which wheat has been grown continuously since 1883 were found to be 

 in bad condition, chemically and physically. They do not retain water well in the 

 cultivated portion, and failed to mature a crop of wheat in the dry season of 1900. 

 The available plant food and the principal feeding ground of the wheat roots seems 

 to be in the first 8 in. of soil. . .' . 



"Newly broken soils do not blow. . . . The great mass of fine roots intertwined 

 about the particles of soil in the virgin prairie prevented the soil from blowing." 

 The same result may be attained by adopting a system of rotation which includes 

 grass. 



"The system of agriculture most nearly ideal for maintaining soil fertility would 

 be one with 2 years in grass followed by cultivated crop, then 2 years in grain crops, 

 making a 5 j'ears' rotation." 



The decomposition and transformation of nitrogen compounds in soils by- 

 lower organisms, and their influence on the grovrth of plants, \V. Kru(;er 

 and W. StHNEiDEWiND (Ldndir. Jahrh., 30 {1901), No. 4, PP- 6S3-64S, pi. 1; ab.^. in 

 Dent. Ijmdir. Preane, ^8 {1901), No. 73, p. 619).— On the basis of the results of plat 

 and vegetation experiments during 1900 the authors conclude that the effect of 

 coarse manures in interfering with the assimilation of nitrogen of the soil lij' plants 

 is due not only to denitrification l)ut also largely to the transformation of assimilable 

 nitrogen (including that of ammonium sulphate) into insoluble and unassimilable 

 nitrogen compounds (albuminoid substances). For previous investigations of the 

 authors on this subject see E. S. R., 12, p. 728. 



On the action of organisms in soils and manure, L. Hiltner {Dent. Landw. 

 Presse, 28 {1901), Noti. 24, pp. 203, 204; 25, pp. 212, 213; 27, pp. 231, 232).— k general 

 discussion of this subject. 



On nitrification and denitrification, A. Beddies {Cliem. Zig., 2-5 {1901), No. 49, 

 pp. 523, 524; nb.9. in Clu'in. CeiithL, 1901, II, No. 3, p. 222. 



Treatise on the origin and formation of soils, L. Milch {IXo' (irnDdhujcn. der 

 Bodenkunde. Leipsic: Franz Deuticke, 1901, pp. 162; (dn<. in Geo!. CentJiL, 1 {1901), 

 No. 19, p. 581). — This ]*ook discusses the more important mineralogical and geolog- 

 ical facts relating to soil formation. 



The vertical movement of the surface soil, Ii. Darwin ( Rcr. Sri., 4. aer., 16 

 {1901), No. 6, pp. 183, 184). — This is a note on a communication to the Royal Society 

 of London on observations, in continnatiou of those of the eider Darwin, on the rate 

 at which stones and other ol)jects left on the surface sink into the soil. 



What is a steppe ?( T. I. Tanfilvev {Ahs. in Zlnir. O/miln. Aijron., 1 {1900), No. 

 3, pp. 278, 279). — The author gives the following definition: " A stei)pe is a more or 



