68 THE SOILS AND CROPS OP THE FARM. 



that it is not wise to attempt to specify the best dis- 

 tance apart. In prairie soils, 100 feet apart is usual- 

 ly a safe distance, even when the land is quite wet. 



Cost of Tile Drainage.— What is known as 

 "thorough drainage" is rare in this country. The 

 cost would be so great that the practice is not advis- 

 able on lands of moderate price. In many cases the 

 cost would be greater than the price of lands equally 

 desirable and not needing much drainage. Drainage 

 is a permanent improvement, and if a fair interest 

 on the amount invested in it be returned by the in- 

 creased crops, the outlay is advisable. With drains 

 three feet deep and with tile obtainable near the 

 farm, using the sizes most common, the total cost of the 

 work may vary from fifty to seventy-five cents per 

 rod. 



Bate of Fall. -A line of tile laid on an exact 

 level in wet land would carry off much water, if one 

 end were open. A slight fall would greatly increase 

 the carrying capacity, of the tile. It is difficult to 

 have tile laid with accuracy; hence more fall is de- 

 sirable. A fall of one foot in one hundred of length 

 is abundance. Good work is done by many ditches 

 where the fall is not one-tenth this rate. On level 

 land a safe rule is to get all the fall practicable, but 

 not to leave the work undone because the fall is slight. 

 In case of very slight fall the rate can be increased by 

 making the ditch shallower at the upper end. 



Planning and Making the Drains.— It is 

 wise to lay out the plan for a system of drains for the 

 farm; but the work may commence where it is most 

 needed. The advice and work of a drainage engineer 

 is helpful but not essential. A good outlet is essential 



