METHODS OF CONTROL 193 



be used for sub-irrigation, a very desirable 

 method of watering the beds. 



A cheaper method of steam sterilization 

 is the "inverted pan method," which may 

 also be used to sterilize seed beds and 

 frames outdoors. The method has given 

 excellent results and because of its sim- 

 plicity and small cost is recommended 

 for use in large or small areas. It is the 

 invention of Mr. A. D. Shamel of the 

 United States Department of Agricul- 

 ture. The apparatus consists ef a gal- 

 vanized iron pan 6 ft. by 10 ft. and 6 in. 

 deep, which is inverted over the soil to 

 be sterilized, and steam is admitted under 

 pressure. The pan is supplied with steam 

 hose connections, has sharp edges which 

 are forced into the soil on all sides to pre- 

 vent the escape of steam, and is fitted with 

 handles for moving it from place to place, 



