210 an":n"ual eeports of depaetment of agriculture. 



experiments liave shown a new type of organic constituents, classed 

 chemically as aldehydes. These aldehydes originate by processes 

 of organic decay under conditions of poor aeration or drainage and 

 appear to be closely associated with acid soils, though not exclusively 

 so. These aldehyde constituents are for the most part harmful to 

 plants. Two of these soil compounds have been subjected to field 

 tests on several soil types. On some of the types they are quite 

 toxic, while on other types with oxidation, good lime content, and 

 other soil factors making for a strong, virile soil, they are less harmful, 

 or even quite innoxious. Interesting information regarding the 

 specific effects of fertilizers in ameliorating the harmful properties of 

 these compounds in the field has also been obtained. The solution 

 of this problem is especially valuable m dealing with certain highly 

 manured and fertilized garden and greenhouse soils which have been 

 showing a falling off in crop yield. Further progress has also been 

 made in the nature of the organic soil nitrogen compounds by the 

 further isolation and identification of a compound belonging to a 

 different type than has hitherto been found in soils and marking 

 another step in our understanding of the processes of nitrogen trans- 

 formation m soils. 



In this connection a study of nitrogenous fertilizers and their 

 decomposition in the soil was undertaken. The fertilizer of most 

 mterest m this investigation was that prepared commercially from 

 cheap trade wastes by chemical treatment. The nitrogen m the 

 untreated trade waste has proved to be of little agricultural value, 

 but after treatment of the waste is rendered more available. This 

 is shown to be due to the change of difficultly decomposable com- 

 pounds by the treatment into easily decomposable and readily 

 assimilable nitrogen forms. These nitrogen compounds have in part 

 been isolated and identified. Some of these are apparently directly 

 used by the plant, while all are much more easily attacked by the 

 soil organisms with the formation of ammonia or nitrates than is the 

 original trade waste. 



Some further residts have been reached pointing to the fact that 

 in part at least soil compounds have arisen m the soil during the life 

 of the plant. Molds have been found to contribute sod compounds as 

 the result of their development in the soil. In the study of the effects 

 of specific nitrogen compounds it was found that two of these, other- 

 wise closely related, nevertheless showed such striking differences that 

 one was beneficial, w^iereas the other was harmful, producing a de- 

 cided derangement of the normal behavior of the growing plant. 



