THE PROBLEM OF TILLAGE 



horse gang weeders which cover the 

 ground very rapidly. Weeders are use- 

 ful for three purposes — (a) to kill very 

 young weeds, (b) to preserve a shallow 

 mulch, (c) to cover broadcasted seed. A 

 weeder is not effective unless it is used 

 often enough to prevent any weeds from 

 getting too large to be destroyed. Since 

 the weeder stirs the soil only an inch and 

 a half to two inches deep, it should be 

 supplemented by the cultivator, when- 

 ever the soil gets hard. 



Rolling. 



In dry-land farming rolling is very 

 important, because it compacts the sur- 

 face soil and brings the particles closer 

 together, so that the film water passes up 

 more readily by capillary attraction. 

 While passing upward it comes in con- 

 tact with the roots of the plants and is ab- 

 sorbed by them, but this water wiU pass 

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