SELECTION OF PEAT LANDS FOR DIFFERENT USES 17 
profitable through the organization of main waterways for irrigation 
or temporary flooding. Close spacing of relatively shallow ditches or 
of box drains and tile is believed to be preferable, since it results in a 
more rapid run-off and more uniform lowering of the water table 
between the ditches. Variation in water level is less and the rate of 
flow of water is generally better in the loose than in the more com- 
pact and finer textured layers of peat. In the carbonized and dis- 
integrated phases of fibrous peat land a wider spacing of deeper 
ditches is usually followed. Layers of this stage of disintegration 
tend, however, fo retain the moisture, retard the movement of water 
through the soil to the outlet, and consequently lead to an uneven 
shrinkage and to irregularly sloping surfaces when the distance 
between drains is too great. As many laterals as possible should 
drain into each main ditch. A system of moderately deep ditches or 
drains with close spacing appears, therefore, to be more desirable 
even in the case of well-decayed phases of fibrous peat land. Under 
these conditions it would seem that the spacing of box or tile drains 
should not exceed 200 to 300 feet and the depth of the drained hori- 
zon should not be greater than 214 to 3 feet, depending upon the crops 
to be grown and the amount of rainfall. 
Areas of peat land which have very coarse fibrous layers at dif- 
e rent ranges of depth below the surface eventually may cause more 
or less settlement upon subsequent decomposition. There are instan- 
ces also where swelling and upward expansion of layers of spongy, 
fibrous peat have been observed during wet seasons following a pro- 
longed dry period. Units of peat land containing these types of 
material may show curved surfaces, bulging sufficiently to cause 
crops to suffer from lack of moisture. A system of water-level con- 
trol provides the most satisfactory method to avoid this difficulty. 
The chief damage from drainage to woody peat lands is limited to 
crumbling. This may gradually obstruct or block open ditches and 
finally lead to a renewed rise of the water table and to water-logged 
conditions. Where the quantity of water to be drained is relatively 
large, drains and ditches in woody peat erode more easily than the 
ditches in fibrous-peat land. On that account the ditches should be 
given sloping walls in the more decaved and also in the mixed phases 
of peat layers. 
So important is the control of the water relation to peat-land util- 
ization and so definitely useful is it to crop production that the closest 
attention and cooperation in this matter is well deserved. The 
experience of drainage districts and the publications of experiment 
stations? clearly indicate that a successful solution of the drainage of 
Da lands means much to the prosperity of the States concerned. 
any early settlers have failed because the drainage was either 
excessive or not complete and because supplementary drains or dams 
and checks for the control of the water level were not put in to 
maintain favorable moisture conditions for tillage and manurial 
treatments. Moreover, except in certain areas it has been exceedingly 
difficult to bring about a control of the water level. 
The significance of a well-balanced water supply throughout a crop 
season becomes clearer when it is recalled that the specific water 
? The following serial numbers refer to publications on drainage in ‘Literature cited,” at the end o 
this bulletin: 2,7, 16.18.21, 22.24 
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