365 



a large number of fruit trees in full leaf were blown down, in spite of 

 strong stakes, because the earth, which was wet through, did not support 

 the roots sufficiently. This was especially noticeable if a part of the field, 

 with the surrounding avenues of fruit trees, was flooded with liquid sewage. 



Sugar and fodder beets, carrots and similar roots irrigated during 

 the growing season, could not withstand liquid sewage about their crowns 

 for any length of time. In a few hours the leaves began to zvilt and towards 

 evening the petioles became limp. Grains, grass, legumes and other plants 

 withrut fleshy roots did not react in this way. Probably the wilting is 

 physiological since the scanty root fibers present on each fleshy root cannot 

 draw enough water from the highly concentrated soil solution to make 

 good the loss from evaporation. If the concentration of the soil solution 

 was decreased by the absorption of the soil, the wilting disappeared. 



To avoid this, dams one meter wide were built, or the roots were hilled 

 up as they grew and irrigated in the furrows thus produced. 



Attention has been called in another place to the change in the growth 

 of grasses. On the Berlin sewage beds, Lolium italicum abounds and often 

 is entirely killed if irrigated in winter. 



The softness of the grass, indicated by its easy decay, is also caused 

 chiefly by an excess of nitrogen. On an average, in the years 1900 to 1902, 

 a hectare of the Berlin sewage land received 800 to 1200 kg.' Nitrogen^ 

 In spite of the very sparse seeding and the widely separated planting the 

 over- fed grain plants are usually inclined to lodge. I had an opportunity 

 to study the process taking place in this lodging of oats on the Berlin sew- 

 age beds-. In this, a peculiar softening of the leaf tissue, due to bacteria, 

 was noticeable. Regarding the behavior of young seedlings with over- 

 fertilization, I observed in barley, that, in comparison with the normally 

 nourished plants, over-fertilized ones became a darker green, but were back- 

 ward in growth. Then the tips of the leaves bore greyish yellow spots and 

 finally turned entirely grey; at this time a number of seedlings lodged. Soon 

 after lodging, the part of the stalk above the bend began to dry. But while 

 plants normally drying finally assume a straw color, only the lower leaves 

 in this case became straw-colored and the upper ones dried to a hay green 

 color. Of importance here is also the diseasing of the vascular bundles 

 ind the great predisposition of the plants to attacks of fungi"*. 



Besides the well-known delay in the ripening of grain on sewage 

 fields. Ehrenberg also mentions the change in the proportion between the 

 yield in straw and grain. In irrigated oats the proportion of grain to straw 

 was as I :3.33, in non-irrigated, as i :2.88. 



Such a "luxurious growth of straw" gradually becomes typical, for 

 seven newly grown varieties of barley gave an average proportion of grain 



1 Backhaus, Landwirtschaftl. Ver.suche auf den Rieselg-iitern der Stadt Berlin 

 im .Jahre 1914. 



" Soiauei-, P., Beitrag zur analomischen Analyse rauchbeschadig-ter Pflanzen. 

 Landw. Jahrbiicher von Thiel., 1904, p. 593. 



■■! Loc. cit. p. 646. 



