I9I2] Fred J. Seaver and Ernest D. Clark 417 



especlally recommended in the case of seed-beds prepared for start- 

 ing tobacco plants. Portable boilers with inverted pans and other 

 apparatus for sterilizing the soll with steam have been described, 

 and the results discussed in publications from the Connecticut Agri- 

 cultural Experiment Station^ and from the Bureau of Plant Indus- 

 try at Washington.^ In a bulletin^" from South Africa the advan- 

 tages of soil sterilization are called to the attention of the tobacco 

 growers, the increase of plant food being especially noted. Burn- 

 ing brush or similar material upon the soil seems to yield better 

 results than the use of steam. Now, in all these reports upon the 

 favorable results of heating soils we find little reference made to 

 any effects except the desirable ones of killing the spores of parasitic 

 fungi, etc. The chemical changes that may be produced are almost 

 wholly ignored, yet, even under the condition of the rather low heat 

 obtained with the steaming apparatus, such changes apparently have 

 a stimulative and beneficial action on the plants. Furthermore, we 

 believe the almost universal practice of "sterilizing" the soil to be 

 used in physiological and culture experiments should be applied 

 with caution, and with due recognition that the resultant chemical 

 changes in such soils may vitiate experimental results and prove 

 more disconcerting than the undesirable factors in untreated soils. 

 Observers in certain districts in Maine and other parts of the 

 country where blueberries flourish over large areas, have often 

 noticed that when such areas have been recently burned over the 

 growth was especially luxuriant. The Indians also noticed this 

 phenomenon and so they occasionally set fire to large tracts of blue- 

 berry lands in order to encourage large crops of fruit in the follow- 

 ing two or three summers. In northern New England, blueberries 

 are picked in large quantities for canning, and in these districts the 

 owners of blueberry pastures burn over one-third of such land every 

 third year, thus burning over the whole once every three years.^^ The 



*Hinson and Jenkins : The management of tobacco seed-beds. Bull. 166, 

 Conn. Agric. Experiment Station, New Haven. 1910. 



* Gilbert : The root-rot of tobacco caused by Thielavia hasicola. Bull. 158, 

 Bur. Plant Industry, Dep't of Agriculture, Washington. 1909. 



^^ Scherffius : Sterilizing tobacco seed-beds. Agric. Jour. of Union of South 

 Africa, 2: 418-31. 1911. 



" Munson : The horticultural Status of the genus Vaccinium. Bull. 76, 

 Maine Agricultural Experiment Station, Orono. 1901. 



