104 THE POTATO 



inches) to 0.2 feet (2.4 inches) fall per hundred 

 feet, according to the firmness of the soil through 

 which it is made. Ditches that carry over three or 

 four second feet of water should have less grade. 

 Whenever the current of the water picks up and 

 carries sediment, the ditch will give trouble, be- 

 cause the sediment will be dropped in places where 

 the current is slower and eventually this will 

 choke up the ditch and cause a break. Especially 

 in sandy soil should care be used to get an even 

 and light grade, which should not exceed 1.5 

 inches per hundred feet. Where it is necessary to 

 take a farm supply ditch down a heavy grade, drop 

 boxes should be put in to take care of the excess 

 grade. Farm supply ditches should be so 

 located, if possible, to avoid dikes and flumes. 

 A dike where absolutely necessary should be made 

 of stiflE soil, the banks should be made wide and 

 high, and the dirt for it should not be taken closer 

 than four feet from the toe of the bank on each 

 side. When water is put through it for the first 

 few times, it should never be allowed to run all 

 night, because the soil thus thrown up is loose and 

 readily fills with water. After a few hours' run, 

 the water begins to seep through the banks, and 

 until the dirt in the fills has repeatedly soaked up 

 and settled there is always danger of it breaking. 

 As soon as the dikes are firm and solid, the banks 

 should be seeded to some grass that makes a good 

 sod. Kentucky blue grass and Brome grass 

 (Bromus Inermus) make good sod for holding 

 ditch banks. Sandy soil makes a very unsatis- 

 factory dike, as it never hardens like a stiffer soil. 

 Flumes are unsatisfactory unless well made. Gal- 

 vanized iron flumes give good service. Farm 

 supply ditches should have ample capacity. New 



