258 Bulletin 254. 



county, the increased yield of the first crop is said to have paid the expense 

 of the improvement, and from the more hilly sections in the southern part 

 of the State the yields of all crops are reported to be greatly increased in 

 every case. This unanimity of the statements of the effect of drainage on 

 the crop yields bears in upon one's mind the conviction of its desirability 

 and profitableness. Drainage, wisely applied and well executed, accom- 

 plishes its purpose which is to permit the production of much larger crops, 



IV. The Practice of Under-Draining. 



No exact directions of general application can be given for the prac- 

 tice of drainage. There are so many variable factors that each proposi- 

 tion must be managed individually with reference to these variable 

 conditions. Soils differ in their texture which, in turn, affects the 

 percolation of water; soils of the same texture differ materially in structure 

 or compactness ; they also differ in these points not only from place to 

 place on the same farm or in the same county, but also from surface to 

 subsoil. In some cases the soil is a uniform clay to a depth of many feet, 

 in other places it is a uniform sand or sandy loam of similar depth. In 

 still other places the soil may be made up of alternate layers of these 

 two materials, — ^sand and clay. The layers may be thick or thin, they 

 may be arranged with either the sand or the clay at the surface ; the layers 

 may be continuous or discontinuous. The variation of any of these 

 conditions will modify the character of the drainage system which will give 

 the most eft'ective results. 



In addition to the variations just mentioned, and which refer to 

 the character of the soil, are the variations in slope or fall, in area of 

 land to be drained, in the rainfall, — its amount and distribution — 

 in the accumulation of surface drainage water, in subsurface drainage 

 or seepage, commonly called springs, in the prevalence of flooding or 

 overflow of adjacent streams and in the severity of the winter tempera- 

 tures which will determine the depth to which the 'soil freezes. All 

 these factors must be taken into consideration in planning and executing 

 the drainage system. It is because of these variables that no single rule 

 can be uniformly applied to such details as depth, size of tile and frequency 

 or arrangement of the drains. 



General principles only may be laid down and attention may be called 

 to some of the difficulties likely to arise in order that their occurrence 

 may be avoided. The first broad principle to be kept in mind is that 

 the excess or gravitational moisture in the soil is to be removed to a 

 sufficient depth and with sufficient rapidity to give the plant reason- 

 able root area and freedom from stagnant water for more than a day 

 or two at a time. Second, that water moves with much greater facility 



