426 EXPERIMENT STATION RECORD. 



(4) tSanpete clay. The (rnps .mown in tlic cxiiciiiuciils iucliKlcd corn and 

 wheat. A comparison was niado of evaporation and transpiration front bare 

 and cropped soils, from cultivated and uncultivated soils, and from fertilized 

 and unfertilized soils. 



The data, which are jjiven in detail, show that cnltlxalin^' or hoeins largely 

 reduced the evaporation of water from hare soils. It generally increased the 

 yield of dry matter but largely diminished the amount of water transpired for 

 1 lb, of dry matter and was much nioi-e effective on clay and sand soils than 

 on ordinary loam soils. 



"Shading dinnnished greatly the evaporation from bare soils land] more 

 water evaporated from bare soils under surface ii-rigation than under subin-iga- 

 tion or when the water stood near the surface. 



" In the majority of cases, surface irrigation gave the largest yields of dry 

 matter, subirrigation nearly as much, and standing water the smallest yields. 

 Approximately the same number of pounds of water was required to produce a 

 pound of dry matter under conditions of subirrigation and standing water; a 

 somewhat larger number was required under conditions of surface irrigation. 

 In all probability, the number of pounds of water actually transpired for the 

 production of a pound of dry matter is the same under the various methods of 

 irrigation. 



"Subirrigation was most satisfactory on loam soils. 



"The evaporation of water from bare soils increased with the increased 

 saturation of the soil. The increase in the loss was usually much larger than 

 the increase in saturation. Heavy irrigations should, therefore, be followed 

 by immediate, careful, and thorough cultivation. Increasing the saturation 

 of soils increased in a somewhat larger ratio the yields of dry matter. Ap- 

 proximately the same number of pounds of water is required under various 

 conditions of soil saturation for the production of 1 lb. of dry matter. The 

 amount of water actually transpired for each pound of dry matter ai>pears 

 to be somewhat lower under conditions of high saturation. . . . 



"The yield of dry matter was nuich larger on soils that Iiad rested during 

 the preceding three years than on soils that had been croiii>ed during the same 

 period. The number of pounds of water required for 1 lb. of dry matter 

 was much smaller on the soils that had been bare than on those that had been 

 cropped during the preceding three years. . . . 



" On fertile soils heavy applications of water are not likely to be so wasteful 

 as on infertile soils. . . , Fertile soils will produce crops with a smaller 

 amount of water than will infertile soils. The addition of fertilizers to infer- 

 tile soils enables crops to produce dry matter at a lower water cost. 



" Soils vary greatly in their relationship to plants and water. 



" The seasons have a strong effect upon the yield of dry matter and upon the 

 amount of water required for the production of 1 lb. of dry matter. The 

 number of pounds of water required for the production of a pound of dry 

 matter varies greatly with the crop, the soil, tlie season, the method of irriga- 

 tion, and the cultivation. In general, however, the amount of water required 

 for the production of dry matter is \ ery much higlier in an arid region than in 

 regions of abundant rainfall. The conservation of moisture is, therefore, of 

 greater importance in the West than in the East. 



" Summer fallowing should be practiced on dry farms, first, to store the 

 precipitation of two or more years for the use of one crop, and secondly, to 

 set free an abundance of plant food which will enable crops to mature with 

 less water." 



Methods of bacteriolog'ical investigation of soils, V, F. T.ohnis {Centbl. 

 BaTct. [eic], 2. AM., 'U {1909), No. 5-1, pp. 7S.3-i93).— This article is contro- 



