250 



SCIENCE 



[N. S. Vol. XXXIV. No. 869 



within the experimental error of sampling 

 and analysis. The total organic carbon has 

 markedly increased in the cropped soil. The 

 " humus " has remained practically the same 

 except on the alternate cropped and fallow 

 plot where a decrease has occurred. 



The yearly yields of the plots since the be- 

 ginning of crop production on this farm are 

 recorded in Table H. 



TABLE II. YIELD OF WHEAT ON PLOTS CEOPPED CON- 

 TINUOUSLY AND ALTERNATELY CKOPPED AND 

 SUMMER-FALLOWED 



Yield of wheat reported as bushels per acre 



The alfalfa plot was utilized for experi- 

 ments in alfalfa seed production. No yield 

 of seed was obtained. The seed experiment 

 was discontinued in 1908. In 1909 a yield of 

 2,'7'75 pounds of hay was obtained. The crop 

 failed to mature in 1910. 



With respect to the characteristic cultural 

 methods in vogue in Utah, it may be noted 

 that one of the reasons why the grain is har- 

 vested with the header is that the straw is so 

 short that it is difficult to use a binder. 

 Wherever a binder is used, the straw is of a 

 ranker growth which permits its use. Now, 

 this being true, it is very doubtful if there be 

 more straw in the stubble on dry-farming 

 land in Utah where the header is used than 

 in the stubble on land where the ranker 

 growth of straw permits the use of the 

 binder. The writer confesses that he knows 

 of no accurate data upon this point. 



The explanation of the noted increase of 

 humus and nitrogen in the dry-farming soils 

 of Utah must be sought elsewhere. The effect 

 of the cultural methods, while not of para- 

 mount importance, is a possibility which 

 ought not to be ignored. In many sections of 

 the country, such as the Mississippi valley, 

 there is a sharp line of demarkation between 

 the surface soil and subsoil, due to the ac- 

 cumulation of humus in the surface soil 



formed from the decayed roots of the native 

 grasses and the addition of their residues. 

 The marked change in color of the subsoil 

 indicates that the roots of the native grasses 

 have not penetrated to greater depth. In the 

 soils of Utah, no such line of demarkation 

 occurs between surface and subsoil, which 

 clearly indicates that the roots of the native 

 vegetation have penetrated to great depths. 

 The significance of the deep-rooted character 

 of native plants in arid soil was first noted 

 by Hilgard.' The characteristic native vege- 

 tation of the dry-farming soils of Utah is 

 sagebrush, the roots of which penetrate to 

 great depths and, being of a woody nature, 

 do not undergo decay rapidly. The foliage is 

 very scant and adds little to the humus- 

 forming material of the soil. The native 

 grasses occasionally occurring with sage- 

 brush are also deep rooted. In a word, there 

 is limited possibility for the formation of 

 humus in the virgin surface soil as compared 

 with other sections of the country where the 

 root system does not penetrate so deep and 

 the native vegetation of a humus-forming type 

 is more abundant. Therefore, in the dry- 

 farming soils of Utah, the addition of any 

 straw must increase the organic matter of 

 the plowed surface of the soil as compared 

 with the virgin surface soil which receives 

 little or no organic matter of a humus-form- 

 ing type. The other factors as noted in Bul- 

 letin No. 109 should also be considered in 

 connection with the increase of nitrogen and 

 humus in the cultivated soil. 



Egbert Stewart 

 Chemical Laboratory, 



Utah Experiment Station 



TEE AMERICAN CHEMICAL SOCIETY. Ill 

 division of industrial chemists and chemical 

 engineers 

 G. D. Eosengarten, chairman 

 F. E. Gallagher, secretary 

 The Bapid Analysis of Alloys: Guillermo Pat- 

 terson, Jr. 

 The Testing of Inhs, Typewriter BibboTis and 

 Carbon Papers: Percy H. Walker. 



'"Soils," p. 174. 



