DRAINAfJE. 609 



may be ^ on peat, 1 on clay or stiff loam, 1^ on sandy loam, 

 2 — 3 on sand. 



The main drains may be provided with sluices at suitable 

 places, so that they can be closed and the drainage stopped 

 during dry seasons. 



ill. TiMK FOR Dkaining. 



Drainage should precede planting by a few years, so that 

 the ground may become sufficiently dry and may settle down 

 before the plants are put in ; a dry period of the year, e.g., late 

 summer or autumn, should be chosen for the execution of the 

 work. 



iv. Mkthod of Digging the Drains. 



Operations should be commenced with the main drain at 

 the lowest part of the land, in other respects the system 

 already described for digging boundary-trenches should be 

 followed (p. 18). The earth removed from the drains should 

 not be placed too close to them, as it may then be washed 

 back again by the rain ; it should be used for filling- up 

 hollows or spread evenly over the surface of the ground, 

 which is beneficial in wet places by raising their level. After 

 the main drain has been dug the feeders and leaders should 

 follow. It is most economical to give the work out to be done 

 on contract. 



V. Advantages of the Method. 



The advantages of the method of draining by open ditches 

 when compared with closed drains are : — 

 Cheap execution. 



Ready discovery of places requiring repair, and cheapness 

 of repairs. 

 Its disadvantages are : — 



Loss to the forest growth of area occupied by the ditches. 

 Difficulties in transport of produce. 

 Liability of the ditches to damage by men, cattle, etc. 

 Too complete and rapid removal of water. This may 

 cause temporary injuries for want of moisture in the 

 soil, and may damage lands below the drained area. 

 F.P. R R 



