WATER SOILS. 929 



as wet as the plowed ground, but it rapidly dried out again. The plowed ground, 

 not cropped nor cultivated during the season, was more uniform in its water content 

 than the sod, and was persistently in better condition." 



There was no essential difference at the close of the season in the 

 moisture content of a soil which in the previous spring had been (1) 

 plowed shallow, (2) plowed deep, or (3) sub-soiled. The results of the 

 tests of the effect of salt and gypsum on moisture content were incon- 

 clusive. In a comparison of the loss of water from untreated soil and 

 that cultivated but not cropped, mulched but not cropped, or cropped 

 but not cultivated, the cropped soil dried out most rapidly, the next in 

 order in this respect being the untreated soil. Surface cultivation to a 

 depth of 4 or 5 in. was about as effective in conserving the moisture as 

 the mulch. 



"Experiments with soil in galvanized-iron pots, under well-controlled conditions, 

 showed that a layer of finely pulverized soil § in. thick had no marked influence on 

 the rate of evaporation ; that a hay mulch 2 in. thick checks evaporation most 

 effectively, but that evaporation proceeds at so rapid a rate from bare soil that a 

 mulch, to he most useful, must he promptly applied; that the rate of evaporati >n 

 from a sandy soil is less than that from one less sandy when hoth are kept con- 

 stantly wet, hut if allowed to dry, the sandy soil becomes much drier; that neither 

 salt, gypsum, lime, nor magnesium chlorid exerts any beneficial effect in checking 

 evaporation from the soil, the evaporation being practically the same as from 

 untreated soil." 



Contribution to the study of nitrification in the soil, T. Sciiloes- 

 1NG, Jr. (Comjtt. Rend. Acad. Sci. J'aris, 125 (1897) , No. 21, pp. 824- 

 827). — It is stated that nitrification and microbic combustion in general 

 are less active in fine-grained, compact soils than in lighter, coarse- 

 grained soils. This is generally attributed to the greater facility with 

 which the air circulates in the lighter soils and supplies the necessary 

 oxygen. 



The author shows that in many cases it is not air but available water 

 which is deficient in the heavy soils. 1 As is well known, the fine par- 

 ticles of heavy soils have so strong an attraction for water that a large 

 part of the soil moisture is rendered unavailable for the growth of the 

 higher plants. It appears from these experiments that it is also ren- 

 dered unavailable for the use of the nitric ferment. In order that 

 nitrification may be equally active in light and in heavy soils, the latter 

 must have a higher percentage of moisture than the former. 



1 See also Deherain, Compt. Rend. Acad. Sci. Paris, 121 (1895), pp. 30-35. 



