1912.] PUBLIC DOCUMExNT — x\o. 31. 211 



tiou with a stud}' of the natural fertility of the soil. "Where 

 conditions permit the bog is completely overflowed from some 

 time in Xovember until May, sometimes mitil the latter part of 

 this month. During this period the changes within the soil 

 must be limited to solution of matter in the water and jDutre- 

 f active decomposition in the vegetable matter. Both wull be at 

 the lowest point because of the winter temperature. In the 

 spring, when the sluices are opened, there is a rapid run-off 

 from the surface followed finally by seepage into the ditches. 

 The water table falls in the soil to a point a little higher than 

 the level maintained in the drains. It is only above this water 

 table that the activities of useful bacteria can occur, and while 

 it is not definitely known how deep the cranberry roots pene- 

 trate, it is probable that they do not extend below the permanent 

 water table. Through a large part of the growing season the 

 water is maintained in the ditches at a level 12 to 15 inches 

 below the surface of the soil. This permits oxidation changes 

 and free root development in a soil depth of not more than 1 

 foot. 



Moist sand is a well known medium for «?robic bacterial 

 action, and the same is true of peat when it contains the opti- 

 mum amount of water. Sewage filters are constructed of both 

 types of soils, while several proposed processes for production 

 of nitrates are based on the rapid nitrification known to take 

 place in peat under favorable conditions. 



During the summer season there must be a movement of water 

 upward from the level of the water table into the surface peat 

 and sand. This upward current is produced mainly by the 

 transpiration of water from the plants, as they cover the sur- 

 face so completely that actual evaporation must be small. But 

 this makes little dili'erence since it has been shown that tran- 

 spiration follows the same laws as evaporation from a free 

 surface.^ Botanists have also observed that bog plants, for 

 some reason, take on the character of desert plants and resist 

 transpiration. The peat which is continually saturated or sub- 

 merged must be constantly yielding soluble nuiterial to the 

 enveloping water, and the solution must be nearly saturated. 

 This soluble matter is poisonous to plants of many families, but 



' Montgomery, Proc. Am. See. Agronomy, 1911, pp. 261, 283. 



