Conserving Soil Moisture. 



189 



Table showing the relative effectiveness of soil mulches of dif- 

 ferent depths and different frequencies of cultivation. 



It will be seen that with each of the three depths of cul- 

 tivation the percentage of moisture saved, over that which 

 was lost from the ground not cultivated, increased with the 

 frequency of cultivation. 



219. Too Frequent Cultivation Undesirable. When a soil 

 mulch is well loosened and thoroughly separated from the 

 firm ground beneath, and especially after the mulch has 

 become quite dry, little can be gained by stirring the soil. 

 Indeed it must ever be kept in mind that it costs to cul- 

 tivate a field and when this is done without need the work 

 is a dead loss. Further than this, late in the season, when 

 the surface of the ground has become relatively dry, posi- 

 tive harm may be done by unnecessary cultivation because 

 at this season many plants have put up, very close to 

 the surface, great numbers of fine roots in order to 

 avail themselves of the moisture from light showers and 

 from the dew which may be condensed in the surface layer 



