THE CONTEOL OF SOIL-MOISTURE 221 



The above data, which are amply corroborated by other 

 investigations,^ indicate that, with an nncropped light silt 

 loam in a semi-arid region, the soil-mulch is of little practical 

 importance in conserving moisture. Moreover, the results in 

 Illinois as well as Kansas are no better on cropped land, the 

 cultivation seemingly having little influence on either mois- 

 ture content or crop yield. The importance of a good seed- 

 bed is very strikingly shown by the Illinois data, as is also the 

 necessity of weed control. The weeds not only appropriate 

 moisture that should go to the crop, but at the same time 

 absorb nutrients that should be utilized in other ways. 



Certain general conclusions are unavoidable in respect to 

 a soil-mulch.2 In the first place, a cropped cultivated soil 

 seems no more effective in preventing evaporation than one 

 that is cropped and uncultivated. "Whether this extends to 

 bare soil under all conditions has not been conclusively shown. 

 In the second place, the elimination of weeds seems to be the 

 most important benefit of cultivation. It must be remem- 

 bered, however, that cultivation may exert some benefit on 

 aeration of a heavy soil and certainly encourages granulation 

 to a certain extent. 



114. Summary of moisture control. — Moisture control 

 seems to fall logically under three heads: (1) run-off, (2) 

 drainage, and (3) evaporation. The detrimental influence of 

 run-off over the surface is due to erosion, the loss of the water 



^ Young, H. J., The Soil Mulch; Nebr. Agr. Exp. Sta., 25th Ann. 

 Eep., pp. 124-128, 1912. 



Barker, P. B., The Moistijre Cmtent of Field Soils Under Different 

 Treatments; Nebr. Agr. Exp. Sta., 25th Ann. Rep., pp. 106-110, 19lf. 



Gates, J. S.J and Cox, H. E., The Weed Factor %n the Cultivation of 

 Corn; U. S. Dept. Agr., Bur. Plant Ind., Bui. 257, 1912. 



Alway, F. J., Studies on the Eelation of the Non-available Water of 

 the Soil to the Hygroscopic Coefficient; Nebr. Agr. Exp. Sta., Res. Bui. 

 3, 1913. 



Burr, W. W., The Storage and Use of Soil Moisture; Nebr. Agr. Exp. 

 Sta. Ees. Bui. 5 1914. 



^See Call, L.'e., and Sewell, M. C, The Soil Mulch; Jour. Amer. 

 Soc. Agron., Vol. 9, No. 2, pp. 49-61, Feb., 1917, 



