CITY STREET SWEEPINGS AS A FERTILIZER. 



the roots as well as the tops being affected. Oils from samples No. 1 

 and No. 2 reduced the growth of wheat 10 per cent in the case of the 

 distilled water cultures, and the oil from sample No. 3 reduced the 

 growth 20 per cent. In a solution containing the nutrient salts the 

 oils used in the same amount from sample No. 1 reduced growth 6 

 per cent; from sample No. 2, 7 per cent; and from sample No. 3, 11 

 per cent. 



TEST OF SWEEPINGS AFTER OIL WAS EXTRACTED. 



The sweepings from which the oil had been extracted were next 

 tested as to their effect on growth. The petroleum ether was evap- 

 orated completely from the manure by allowing it to stand in the 

 open for a week or more. The same kind of soil was used as in the 



FIG. 2. Effect of street sweepings and stable manure on radishes. (1) Soil untreated; (2) soil + sweep- 

 ings No. 1; (3) soil + sweepings No. 2; (4) soil + sweepings No. 3; (5) soil + stable manure. 



* 



previous experiments and the extracted sweepings were added to 

 portions of the soil at the rate of 5 tons per acre. Treatments with 

 stable manure* extracted with petroleum ether and also in its natural 

 condition, were included in the test as a means of comparison with 

 the samples of sweepings. The plants were grown in the paraffin 

 pots for 30 days, then the green weights were taken. Three pots were 

 used for each treatment. The growth is given in Table IV. 



TABLE IV. Effect of street sweepings after being extracted with petroleum ether. 



Green weight of 



