TILLAGE AND EVAPOEATION 155 



recent years that confirmation of this important 

 principle has been obtained for the soils of the dry- 

 farm region. P^ortier, working under California con- 

 ditions, determined that cultivation reduced the 

 evaporation from the soil surface over 55 per cent. 

 At the Utah Station similar experiments have shown 

 that the saving of soil-moisture by cultivation was 63 

 per cent for a clay soil, 34 per cent for a coarse sand, 

 and 13 per cent for a clay loam. Further, practical 

 experience has demonstrated time and time again that 

 in cultivation the dry-farmer has a powerful means 

 of preventing evaporation from agricultural soils. 



Closely connected with cultivation is the practice 

 of scattering straw or other litter over the ground. 

 Such artificial mulches arc very effective in reducing 

 evaporation. Ebermayer found that by spreading 

 straw on the land, the evaporation was reduced 22 

 per cent; Wagner found under similar conditions a 

 saving of 38 per cent, and these results have been 

 confirmed by many other investigators. On the 

 modern dry-farms, which are large in area, the arti- 

 ficial mulching of soils cannot become a very exten- 

 sive practice, yet it is well to bear the principle in 

 mind. The practice of harvesting dry-farm grain 

 with the header and plowing under the high stubble 

 in the fall is a phase of cultivation for water conser- 

 vation that deserves special notice. The straw, thus 

 incorporated into the soil, decomposes quite readily 

 in spite of the popular notion to the contrary, and 



