SOIL DISINFECTION 59 



then drenched with a formalin solution composed of one 

 part of commercial formalin (40 per cent formaldehyde) to 

 150 to 200 parts of water, three fourths to one gallon of 

 this solution being used to the square foot of bed space. 

 The solution should be put on with a watering pot with a 

 rose and distributed as evenly as possible over the bed, so 

 as thoroughly to wet the soil to the depth of a foot. It will 

 in most cases be necessary to put this solution on in two or 

 three applications, as the soil will not take in this quantity of 

 water immediately. The beds should then be covered with 

 heavy burlap or a tarpaulin to retain the fumes for a day 

 or so, and then aired for a week before sowing the seed. 



Spring applications of formalin are open to the following 

 objections : The addition of such a large quantity of water 

 to the soil keeps it wet and cold longer than would naturally 

 be the case, thus delaying germination as well as subsequent 

 growth ; the necessity of airing the beds to remove the 

 formalin fumes and to allow the soil to dry out also causes 

 delay in seeding. To obviate these difficulties the beds 

 should be treated in the fall, before freezing. In this case a 

 stronger solution, 1 to 100, may well be used, as there will 

 then be no danger of injuring the seedlings. 



