132 SUCCESSFUL FARMING 



not fully occupy the ground in their early periods of growth. Weeds 

 compete with the farm crop plants for plant food and moisture. Where 

 they have an equal start, they will frequently exterminate the crop 

 unless removed promptly by cultivation. Weed destruction is most 

 economically accomplished by hoeing and cultivating as soon as weeds 

 have begun to grow. WTien such measures have been neglected and the 

 weeds get a good start, it requires much more labor for their extermination. 

 Soil Mulches. Aside from the soil mulch mentioned under the 

 topic of cultivation and hoeing, mulches of straw, manure and other 

 organic substances are resorted to in exceptional cases. These serve 



TERRACING AS A MEANS OF PREVENTING EROSION. l 



both to conserve soil moisture and to keep down weeds. They therefore 

 obviate the necessity for hoeing and cultivating. Such mulches encourage 

 capillary rise of soil moisture to the immediate surface of the ground. 

 Furthermore, upon the decay of the mulch, organic matter and plant 

 food are added to the soil. Such mulches are applicable only under inten- 

 sive systems of farming and where the materials may be secured without 

 too great cost. 



Soil Erosion. Soils are eroded by the rapid movement of both wind 

 and water. Wind erosion occurs most extensively in the sandy regions 



i From Year-Book, U. S. Dept. of Agriculture, 1913. 



