364 



added. The Leguminoseae and other plants disappeared, having been over- 

 grown by the grasses which then ripen more easily than if they have only 

 a nitrogen supply. Stable manure alone also yielded a considerable har- 

 vest of Bromus mollis and Poa trivialis especially, with fewer Legumi- 

 noseae, but it left much to be desired in the fineness and uniformtiy of 

 the hay. 



If mossy meadows are brought under cultivation, the moss cannot en- 

 dure a concentrated nutrient solution, or, at least, a high concentration of 

 various nutrient salts which require still closer examination. This explains 

 the disappearance of moss from meadows after they have been fertilized 

 with potassium. The same behavior is found for the horsetail (Equisetum) 

 which is said to disappear absolutely after the use of calcium chlorid, and 

 seems, on this account, to be especially sensitive to high calcium concen- 

 tration. 



In contrast to the extreme impoverishment of the meadows, manifested 

 by a mossy vegetation, stands the over-powerful development of grass on 

 the so-called rankly growing places. There is an abundant nitrogen fertili- 

 zation from the excretions of animals and its results are shown by a more 

 luxuriant blade development.. According to Weiske^, the plants had nearly 

 twice as much protein but possibly % less of substances free from nitrogen, 

 than the neighboring plants which had not been over-fertilized. Accord- 

 ingly, the ash of the former contained more alkalis, magnesium and sulfuric 

 acid. The plants on such rankly growing places, despite their greater 

 volume, remained in an immature condition. With a greater spread of such 

 over-fertilized places, these plants would become more injurious than bene- 

 ficial. In this they resemble the condition on the sewage disposal beds. 



Sewage Disposal Beds. 



The increased use of sewage disposal beds near large cities requires 

 special discussion of the injuries unavoidable in this practice. Ehrenberg- 

 has recently published his experiences in regard to the Berlin sewage beds. 



Aside from the notably increased development of Plasmodiophora 

 Brassicae, due to the rapidly repeated cultivation of species of cabbages, 

 he reported also injuries due to animal parasites. Most of all occurred 

 the extraordinary increase of Silpha atrata, whereby great areas of beets 

 were completely destroyed. The parasites found over-abundant nourish- 

 ment in the decomposing organic substances of the liquid sewage and, in 

 the dams and canals, lurking places where they were protected from cold 

 and enemies. The great supply of nutrients also attracted the crows from 

 long distances to the sewage beds on which seeds, as, for example, maize 

 and wheat, were uprooted in whole rows. Rats were another pest. 



In addition to the damage done by animal and plant forms, the wind 

 caused more damage here than on other fields. On the Berlin sewage beds 



1 Annalen d. Lnndwirtsch. 1871. Wochonblatt, p. 310. 



2 Ehrenberg-, Paul, Einig-e Beobachtung-en iiber Pflanzenbeschadigungcn durcli 

 Siniljauchenberieselunp:. Zeitschr. f. Pflanzenkrankh. 1906. 



