Treatment of Sick Soils 



41 



more pressure is obtainable, the aforementioned 

 kinds of apparatus may give very good results, but 

 where the pressure is less, as in many cases in steam 

 heated plants, they are not satisfactory. 



The necessary equipment for this new device con- 

 sists of two 2 X 4's cut at suitable lengths, a few 

 boards either the entire length or half the length 

 of the width of the greenhouse, canvas, burlap, 

 sacking or tarpaulin. This method has been devised 

 purposely for greenhouses growing vegetables on 

 the ground, although modifications of this method 

 could be made to suit other conditions. 



The first operation in carrying out the work con- 

 sists of digging a pit at one extremity of the house 

 to the depth that one wishes the soil sterilized. The 

 width and length depend somewhat upon the width 

 of the greenhouse. In our work the pits were dug 

 12 inches deep, 6 to 8 feet wide and lo to 15 feet 

 long. Two 2 X 4's are laid on edge in the bottom 

 of the pit. These pieces should be the length of the 

 pit and placed about 6 to 12 inches from the sides of 

 the pit. One or two leads of steam pipes with T out- 

 lets in the center and at the ends of the pipes should 

 be laid in between these two stringers (2 x 4's). The 

 pipes can best be run in from the ends of the pits. It 

 has been found better to let the steam out in large 

 quantities and not through perforated pipes. Pieces 

 of 2 X 4's are then laid across these two stringers and 

 should be long enough to reach across the width of 

 the pit. Quite a large number are necessary to form 

 a kind of platform. About a quarter of an inch 



