42 
VEGETABLE GARDENING 
melons and cucumbers without animal manure shipped 
from Philadelphia and New York. 
76. Manure as a source of humus. — Many growers of 
vegetables would never buy manure were it not for the 
necessity of maintaining the supply of soil humus. That 
is, it would be cheaper for thousands of gardeners to pur- 
chase commercial fertilizers for the needed plant foods 
than to buy bulky manure, pay freight and then haul 
several miles perhaps, not to mention the cost of spread- 
ing and of composting. But a liberal supply of soil humus 
is absolutely essential to success in growing all classes 
of vegetables. It increases the water-retaining capacity 
of soils ; secures improved soil aeration ; aids important 
chemical changes ; increases soil temperature ; helps to 
create favorable conditions for the work of friendly bac- 
teria ; improves the structure of soils ; makes it possible to 
begin work earlier in the spring and reduces the labor of 
tillage. Animal manures are superior to green manures 
as humus-making materials because they decompose more 
rapidly and are, therefore, of greater value to the crops 
under cultivation at that time. 
77. Manure as a source of plant food. — In many in- 
stances manure is the cheapest source of plant food. 
Gardeners living near the cities often procure it at nomi- 
nal prices. Bolder such conditions it would be unwise to 
make large expenditures for commercial fertilizers unless 
for special foods, such as nitrate of soda. Animal manures 
do not become available so quickly as many forms of 
commercial fertilizers, although composting (86) is of 
great value in hastening decomposition. The following 
table * shows the relative composition and the compara- 
tive value of the manure of various animals. Due to the 
scarcity of manures and the present cost of commercial 
fertilizers, the values expressed in the last column would 
be considerably higher to-day. 
* U. S. Department of Agriculture. Farmers' Bulletin 192. 
