492 Irrigation and Drainage 



marked degree, and if underdrains were laid at once, 

 the lines of the tile would ultimately be found too 

 close to the surface. It is, therefore, usually better 

 in such cases to drain first with open ditches, plac- 

 ing them where ultimately they may be deepened 

 and converted into underdrains. The surface ditch- 

 ing will dry out the marsh to a considerable extent, 

 and permit the needed decay and shrinkage of the 

 peat to take place, although several years may be 

 required for this. 



If the peat is very coarse and thick, and if little 

 vegetation grows upon it, it may be well to burn it 

 over several times when not too dry, in order to 

 increase the silt and ash in the soil and to hasten 

 the shrinkage. The ash thus formed will so much 

 improve the texture of the surface as to very mate- 

 rially assist in getting a crop started upon the area. 



It is very important to get a crop started upon the 

 soil as soon as practicable, because this greatly facili- 

 tates and hastens the rate of decay. This should 

 be done, even though it may not be remunerative in 

 any other way than that of improving the texture of 

 the soil. 



