154 TILTH AND TILLAGE 



Flankers. Sometimes, as in tobacco culture, and in market 

 gardening, the planker is used when it is desirable to leave the 

 surface particularly even and finely pulverized without firming it 



FIQ. 94. Spring tooth harrow. 



(Fig. 95). This tool is usually made out! 'of three to four eight- 

 inch or ten-inch planks bolted together with their edges overlapping. 

 The planker is not a compacting implement. 



FIG. 95. Planker. 



Rollers and Clod Crushers. Lumps are easily broken by means 

 of rollers and clod crushers (Fig. 97). Very often, after harrowing, 

 the seed bed is too loose or has not sufficient contact with the sub- 

 soil. If such be the case, rolling is necessary to compact the soil. 

 Of all tools used for this purpose there is none better than the cor- 



