CROPS AND SOIL IMPROVEMENT 



to 100 feet, one may assume that a 6-inch main will 

 carry the surplus water from 12 to 20 acres of 

 land, and an 8-inch main will carry the water of 

 twice that area. Some drainage experts figure 

 larger areas for such mains, but there is danger 

 of loss of crop when the rainfall is very heavy. 



The laterals need not be larger than 3 inches in 

 diameter when laid on a good bottom. 



Kind of Tile. When clay tile is used, it should 

 be well burned. Some manufacturers offer soft 

 tile for sale, as the loss from warping and crack- 

 ing is less in case of insufficient burning. The 

 claim may be made that the efficiency of soft tile 

 is greater than that of the hard tile whose porosity 

 has been destroyed. This is an error, as the water 

 enters the drain at the joints, and not through 

 the walls of the tile. Underdrainage should be 

 permanent in its character, and it is essential that 

 every piece of tile be sound and well-burned. 



Vitrified clay tile is good for drainage, but no 

 better than common clay hard-burned. 



Round or octagonal tile is the most desirable 

 because it can be turned in laying to secure the 

 best joints. Collars are not needed in ordinary 

 drainage. 



Cement tile is coming into general use in regions 

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