18 BULLETIN 108, U. S. DEPARTMENT OF AGRICULTURE. 



In Table X are given the remaining soils, which gave none or only 

 an insignificant amount of extractive material when subjected to 

 the method for obtaining aldehyde from soils, nor did this extract 

 give the reactions with the above reagents. We must conclude 

 therefore that the aldehyde material, salicylic aldehyde or other 

 aldehydes, are either absent or present in much smaller quantities 

 in the soils of Table X than in the soils given in Table IX. 



From Table IX it will be seen that the soil aldehyde is in every 

 case harmful to growth, and that all the soils behave in this respect 

 like the Mount Vernon soil (No. 1), which has been already more 

 fully described and in which salicylic aldehyde of poisonous proper- 

 ties was demonstrated. 



In Plate V, figure 1, is shown the effect of this material from soil 

 No. 2. This had been used for gardening and trucking for the last 

 10 years, and had been manured each year with poultry manure 

 and commercial fertilizers. The soil in the last two years produced 

 poor vegetables and truck crops, and corn failed entirely. The soil 

 is grayish yellow in color, is quite acid and low in organic matter. 

 The separated aldehyde extract was harmful to the growth of wheat 

 seedlings, causing a decrease of 33 per cent. 



In figure 2 of Plate V is shown the effect of the aldehyde extract 

 from soil (No. 4), showing an alkaline reaction. This soil had been 

 growing vegetables and truck crops for 20 years with frequent use 

 of commercial fertilizers. Corn, cabbage, and cantaloupes had 

 failed in certain sections of the field for the last two years, whereas 

 formerly the soil grew excellent truck crops of all kinds. The soil 

 and subsoil were quite alkaline to litmus paper, and both showed 

 the presence of considerable aldehyde material. This aldehyde re- 

 duced growth of the test plants by 26 per cent, both tops and roots 

 being severely injured. 



The heavily manured greenhouse soil (No. 5, Table IX) is particu- 

 larly interesting in that considerable aldehyde was found, whereas 

 neither the raw soil (No. 8, Table X) nor similarly treated soil which 

 had been used and then weathered for some time (No. 7, Table X) 

 contained the harmful aldehyde material. This examination was 

 made because the soil in question had been used on benches for 

 floriculture and did not give good results. Soil No. 5, Table IX, 

 was a composite taken from two benches in the greenhouse where 

 carnations and roses did not thrive. This contained aldehyde, 

 which, when tested with wheat seedlings, gave reductions in growth 

 of 35 per cent. Soil No. 7, Table X, had been previously used for 

 greenhouse purposes and had been made in the same way by manur- 

 ing heavily the raw soil, but without experiencing any difficulty. 

 Since then it had been in a pile outside for several months. At the 

 time of testing no aldehyde could be found, nor was the residue 



