392 



on trees does net make itself felt until the year following its application, 

 but then has a continuous action up to the third year. From my own ex- 

 periments, in which sewage was used, I consider the increased tendency of 

 the fruit to decay, especially when it begins at the core, as well as the greater 

 susceptibility to frost, to be the effect of a one-sided, excessive nitrogen 

 fertilization. Calcium phosphate counteracts this evil. Experiments with 

 apple trees, abundantly fertilized with saltpetre, showed that the fertilized 

 trees suffered more from aphids than did unfertilized trees\ 



The foliage of Ailanthus glandulosa growing in well-fertiUzed positions 

 became yellow and the branches blighted. On the cut surfaces of fresh 

 branches Peniciliium developed abundantly. The sugar content of the 

 tissue at this place was very great. 



In orange plantations, fertilized trees tended to gummosis and the dis- 

 ease called "Die-back" in Florida is traced directly to over-feeding with 

 organic nitrogenous compounds. These orange trees are said also to be 

 more susceptible to insect attacks". 



Over-Fertilization of Vegetables and Other Field Crops. 



Although our vegetables, as a whole, in their present form, are the 

 product of a high degree of cultivation, and have adjusted themselves to 

 abundant fertilization, we still often find cases of disease due to over- 

 fertilization, especially where sexvage has been used. There is a perceptible 

 increase of the easily oxidizable substances which turn brown in the air. 

 In this case, the walls of the ducts turn brown and, not infrequently, some 

 of the ducts are filled with an inky fluid. Bacterial decay occurs frequently 

 in over- fertilized plants. Peas and other Leguminoseae withstand least of 

 all an excess of nitrogen while increased adaptation is found in some Um- 

 belli ferae, as celery for example. But even here the favorable amount is 

 often exceeded in sewage bed cultivation. If the cut surface of fleshy 

 root tubers becomes rusty, the tubers as a rule have lost in flavor. The 

 more advanced stage, frequently found in vegetables shown in the markets 

 of- large cities, consists of an increased sponginess of the tissue and a greater 

 brown spottedncss. Such conditions and the bacterial decay, connected 

 with them, manifest themselves in cabbage plants accustomed to nutrient 

 solutions of the highest concentration. Under such conditions it is ad- 

 visable to add calcium phosphate and to cultivate continuously. 



Owing to the increased use of rhubarb stalks as a spring sauce, the 

 plants are being cultivated on sewage beds. In such plantations I observed 

 cases where the unusually thick stems were absolutely insipid.- Thus a 

 scanty production, or a complete consumption of the organic acids, is con- 

 nected with over- fertilization. In my opinion this regression in the amount 



1 Fiinfter Jahresber. d. Grofsherzogl. Obstbuuschule zu Friedberg i. d. W. 



2 Webber, H., Fertilization of the soil, etc. Yearbook U. S. Depart. Agric. 

 for 1894. Washington 1895, p. 193. 



