SPECIAL FARM TOPICS 263 



teristics. It follows that in practice drains are placed from 30 to 

 300 feet apart and from l 1 /^ to 4% feet deep. These various condi- 

 tions can not be described in sufficient detail to give a clear under- 

 standing of the requirements of each soil. In case of doubt regard- 

 ing the proper distance apart for drains, they may be so placed that 

 in case more perfect drainage is required a line may be laid midway 

 between the lines. In general, close soils which consist largely of 

 clay should have drains from 40 to 75 feet apart, and open soils from 

 80 to 300 feet apart. In the first instance, which is the more fre- 

 quent system, tiles 2^2 to 3 l /2 inches in diameter may be used for 

 laterals, and for the greater distance those 3M> to 5 inches in diam- 

 eter should be used. It may also be said that one line of 5-inch or 

 6-inch tile may sometimes be used in such a way as to afford good 

 drainage to an entire field. (F. B. 187; Ark. Ex. Sta. B. 104.) 



Location. One of the most important considerations in a sys- 

 tem of drainage is the location, especially as regards the outlet. A 

 field, of, in fact, an entire farm, may sometimes be thoroughly 

 drained by simply laying large tiles in those parts which are uni- 

 formly too wet for profitable cultivation. This is on the theory that 

 the other parts have sufficient natural drainage. In such cases main 

 lines should be located in the course of natural surface flow, with due 

 regard also to straight courses. Branch lines should follow the 

 same general law. This does not mean that the curves and crooks 

 which are always found in natural depressions should be followed. 

 Land which requires drainage always lies in natural areas of greater 

 or less size, each having one point to which all drainage must finally 

 come. These general areas are again divided into subareas each 

 having its outlet within the limits of the general area. The bound- 

 aries of these areas should first be determined and the plans so made 

 that when the drainage is completed the entire tract is provided for. 

 A failure to do this is a fruitful source of disappointment to the 

 farmer. The outlets should always be at the lowest available point, 

 BO as to secure the greatest amount of fall. Just as few outlets should 

 be had as possible, as they are frequently a source of trouble. 



Next locate the main, having it follow the line and direction of 

 the lowest lying ground. This can be done by noticing the channel 

 in which the greatest amount of surface water tends to run after a 

 heavy rain. The main will thus be likely to have a location some- 

 where near the center of the area drained rather than on one side of 

 it. Of course, when this is done, the laterals entering from both 

 sides drain a certain amount of ground already drained by the 

 main, but as the main in this case is supposed to be in the lowest 



ground most needing drainage, the extra amount does no harm, 

 n a comparatively flat piece of ground, where there are no partic- 

 ular low-lying channels, it is better to locate the main at one end or 

 side and place the laterals in parallel lines at nearly right angles to 

 it. (F. B. 187; N. H. C. B. 118.) 



Efficiency of Tiling. Again it should be emphasized that while 

 plants require a moist soil, they cannot grow in a wet one. The tile 

 removes the surplus water. Plain roots need food from the air just 



