24 GARDEN FARMING 



fungi, such as mildews, molds, and damping-off fungi, which cause 

 heavy loss under certain conditions. Besides these advantages ster- 

 ilization also produces a decided benefit by liberating plant food 

 and improving the mechanical condition of the soil. For best re- 

 sults, in spite of what has already been said in regard to the advan- 

 tages of a long compost period, sterilization should be performed 

 immediately before the compost goes into the benches ; or in some 

 cages where proper equipment is available it has been found most 

 economical to sterilize the soil after it has been placed upon the 

 benches. Early sterilization gives opportunity for reinfestation and 

 interferes with the action of the ferments and bacteria of a highly 

 beneficial order. It is, therefore, best to defer all sterilization until 

 after the period of composting has been completed, and to take the 

 soil directly from the sterilizing boxes to the greenhouse bench. 



How to sterilize the soil. There are two means at our command 

 for sterilizing soil to rid it of eel worms. These two means con- 

 sist of the two extremes of heat and cold. Repeated freezings are 

 as satisfactory for sterilizing greenhouse soils to rid them of the eel- 

 worms, injurious to most greenhouse crops, as is heat ; but unfortu- 

 nately not all garden or greenhouse operations are conducted under 

 conditions which will permit of subjecting the soil to repeated 

 freezings and thawings in order to sterilize it. To be independent 

 of any emergency that may arise, the grower must therefore rely 

 upon the use of heat to sterilize soil. For this purpose it has been 

 found that plank boxes about 2 feet deep, 4 to 6 feet in width, and 

 of any desired length sufficient to hold from one to five cartloads of 

 soil, serve the purpose well. These boxes are usually placed so that 

 the tops are flush with the surface of the ground, in order that the 

 soil when shoveled from the compost heap can be dumped directly 

 into the sterilizing boxes. The pipes through which the steam 

 is conducted may be either agricultural tile laid in the bottom of 

 the boxes, or perforated pipes such as are used for steam or water, 

 so arranged that the distance between the pipes is sufficient to 

 permit the use of a spade or shovel. In all cases the line of per- 

 forations should be on only one side of the pipe. In the construc- 

 tion of the boxes these perforations should look downward instead 

 of upward. The reason for this is that the soil is liable to be 

 packed into the perforations if they are upon the top or sides of 



