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MISC. PUBLICATION 6 5 6, U. S. DEPT. OF AGRICULTURE 



Figure 17. — Special attention should be given low places in tobacco fields. Lack 

 of adequate grade in these tobacco rows has caused serious damage. 



up the hill several row widths and starts a new guide row. From 

 this point, the procedure is the same as with the first guide row. 



3. Where terraces drain in opposite directions: Occasionally one 

 terrace drains in one direction while the one above or below drains 

 in the opposite direction. Where this occurs, rows can be laid out 

 so as to flow in either direction. If row drainage in the same direc- 

 tion as the lower terrace is desired a temporary terrace line, draining 

 in that direction, should be staked out near the upper terrace (fig. 

 16, C). On the other hand, if row drainage in the same direction 

 as the upper terrace is desired, then stake out a temporary terrace 

 line — draining in that direction — along the lower part of the interval, 

 and lay out the guide row between this and the upper terrace. In 

 both cases additional fall can be given if needed. 



4. When more grade is needed: Frequently, areas are encountered 

 where additional row grade will be necessary- to provide row drainage. 

 These areas can be low spots, humps, or sections between parallel ter- 

 races as mentioned previously. They should be crossed by gradually 

 dropping the guide row downhill without use of the string. The use 

 of some type of level will be helpful though not necessary in laying 

 out the guide rows through such areas where extra fall is desired. 

 Sighting back with the eye will usually show whether or not sufficient 

 fall has been secured. It is important that special attention be given 

 such places in order to provide adequate grade if the row system is to 

 function properly, otherwise a break may occur as shown in figure IT. 



5. Where rows empty into drainageways : It is necessary to provide 

 free drainage of crop rows into drainageways to avoid having breaks 

 near the row ends. This may be accomplished by turning the ends 

 of the rows slightly downhill where necessary. 





