HARMFUL SOIL CONSTITUENTS 167 



hyde in the mannite solutions to prevent decomposition. Other 

 sets of solutions similar to these were analyzed, and the results 

 were substantiated. In every case 25 to 50 parts per million of 

 salicylic aldehyde in nutrient solution with mannite prevented 

 any bacterial action. The green weight of the plants grown in 

 one set of the solutions is given. in the last column of the table. 

 It is again seen here, that the salicylic aldehyde is harmful to 

 growth of plants as well as to bacterial life. 



The existence of mannite in the Mount Vernon garden soil is 

 probably made possible by the simultaneous presence of salicylic 

 aldehyde. Without any antiseptic action of this kind, mannite, 

 if formed, would immediately be destroyed by soil organisms and 

 probably could not exist as such for any length of time. 



This garden soil has grown box hedges, roses, and other peren- 

 nial garden plants for years and manure has been liberally ap- 

 plied. The subsoil is of such a nature as to prevent the proper 

 movement of air and moisture. An examination of the soil in 

 the laboratory showed that the surface soil was acid and the 

 sub-soil decidedly so. The growth of the garden plants had 

 become poor, and they showed signs of going backward in cer- 

 tain locations. 



As a result of the laboratory examination lime and phosphatic 

 fertilizer were applied and provision made for better drainage 

 so that moisture and air may better circulate, and better results 

 have been secured. Data have been secured in this laboratory 

 which show that the harmful effects of aldehyde on plants is 

 partly overcome by lime- and by phosphates. When conditions 

 in the soil are such as to change or destroy the harmful com- 

 pound salicylic aldehyde, soil organisms and other natural proc- 

 esses of the soil would prevent the formation or destroy im- 

 mediately after formation such an unstable compound as mannite. 



