SHADING AND EVAPOKATION 



151 



tions, it was found that shading a pot of soil, which 

 otherwise was subjected to water- dissipating influ- 

 ences, saved 29 per cent of the loss due to evaporation 

 from a pot which was not shaded. This principle 

 cannot be appHed very greatly in practice, but it 



Fig 34 Alfalfa in rulti\ ated row b This practice is employed to make 

 possible the growth of alfalfa and other perennial crops on and lands 

 "without irrigation. 



points to a somewhat thick planting, proportioned 

 to the water held by the soil. It also shows a jios- 

 sible benefit to be derived from the high header 

 straw which is allowed to stand for several weeks 

 in dry-farm sections where the harvest comes 

 early and the fall plowing is done late, as in the 

 mountain states. The high header stubble shades 

 the ground very thoroughly. Thus the stubble 

 may be made to conserve the soil-moisture in dry- 



