4 CITY STREET SWEEPINGS AS A FERTILIZER. 



The chemical analysis of the three samples is given in Table I, the 

 results being stated in percentage of dry material. The analyses were 

 made by Mr. J. G. Smith, of the Laboratory of Physical and Chemical 



Investigations. 



TABLE I. Analyses of street sweepings. 1 



1 A more extended table of the analyses of such street sweepings made in 1898 is found in Bulletin 55, Divi- 

 sion of Chemistry, U. S. Department of Agriculture. The results, stated in percentages of the original moist 

 material, varied in the different samples from 0.17 to 1.18 for N, 0.01 to 0.16 for P 2 O 5 , 0.08 to 0.50 for K 2 O and 

 6.2 to 52.3 for moisture. 



This table shows each of the samples to contain appreciable amounts 

 of nitrogen, potash, and phosphate, sample No. 1 being somewhat 

 higher in each of these fertilizing constituents. Stable manure, as 

 determined from an average of a large number of samples, contains 

 about 1.6 per cent of nitrogen, 1.5 per cent of potash, and about 1 

 per cent of phosphoric acid, the figures being based on dry material. 

 Comparing these amounts with those contained in ordinary horse 

 manure, 1 it will be seen that the content of nitrogen, potash, and 

 phosphate is higher in the latter. The lower result might be ex- 

 pected, as the sweepings are not all horse manure, but contain con- 

 siderable foreign material, aside from the fact that they are frequently 

 subjected to leaching by rain. 



EFFECT ON GROWTH. 



The efficiency of street sweepings and other manures of this nature 

 as fertilizing material should not be judged merely by the percentage 

 of mineral salts which they contain. The organic material itself has 

 an important bearing on the question, as it may be of such a nature 

 or contain such constituents as to cause it to have either a beneficial 

 or a harmful effect on soils. 



Experiments were undertaken to test the effect of sweepings on crops, 

 by growing plants in soil to which the sweepings had been added. 

 In these experiments a specially constructed paraffine wire pot, 2 

 possessing certain advantages over the ordinary clay pot, was used. 



To test the effect of sweepings on soil, wheat was grown in the 

 paraffine wire pots for one month. The soil used in the test was a 

 clay loam. . The soil was divided into four portions. To three of 

 these was added a sample of one of the three types of sweepings, while 

 to the fourth good stable manure was added, in order that a compari- 

 son might be made. These cultures were checked against the growth 



i Storer, F. H., Agriculture in Some of Its Relations with Chemistry. 

 * For description of method see Circular No. 18, Bureau of Soils. 



