168 TILTH AND TILLAGE 



this respect planting corn in check rows is advantageous. Because 

 of the action of the shovels, proper cultivation leaves a slight slope 

 between the rows. 



The high hilling of potatoes has no particular advantage. 

 When this is done more surface is exposed and hence more moisture 

 is lost through evaporation. When potatoes are grown on the 

 heavier, compact soils, digging is made easier when they are 

 ridged a little; and, moreover, the throwing of some loose dirt 



FIG. 112. Walking weeder and its work. 



on the hills becomes necessary as the potatoes advance in growth 

 to protect the tubers from sunburning, since in many silt loams 

 the growth of the tubers causes cracks to form around the hill, 

 which let in the light. 



Weeders. (Fig. 1 12) . The weeder is a weed-killing and mulch- 

 ing tool consisting of many narrow spring teeth. It is adapted for 

 killing very small weeds in corn, potatoes, etc., either before or 

 after the plants are up. This is not an effective tool when weeds 

 are quite large or when the ground is at all hard or heavy. 



A light, spike-tooth, smoothing harrow is often used in place 

 of a weeder. 



