54 MANAGEMENT OF THE FORCING-HOUSE. 
soil for forcing-houses is increasingly expensive. Besides 
this, it is found that even a rich natural soil cannot carry 
forcing-house tomatoes to their highest productiveness, 
and therefore liquid manure is often used to water the 
soil after the plants have come into bearing. 
“The admirable work on the use of commercial fer- 
tilizers on field tomatoes done at the New Jersey Sta- 
tion has proved that the ripening of the crop may be 
very materially hastened by the proper use of fertilizer 
chemicals, especially of nitrate of soda.* To hasten 
the ripening of crops under glass, where the expense of 
growing them is so much greater than in the field, must 
greatly increase the profits of the business. 
“These considerations have led us to endeavor to 
determine with all possible accuracy how much plant 
food various forcing-house crops take from the soil dur- 
ing their growth, and whether commercial fertilizers can 
be used instead of stable manure, wholly or in part, to 
supply this plant food. A further question also con- 
nected with these is, whether the humus of rotted manure, 
generally regarded as necessary to regulate the storage 
and circulation of moisture in the soil under natural con- 
ditions, can be replaced by some cheap substitute, or 
dispensed with altogether in forcing-house culture, where 
the supply of soil moisture can be well regulated by 
artificial means.”’ 
‘‘Our first endeavor was to find out how much nitro- 
gen tomato plants raised under glass take from the soil, 
in their fruit and vines, and how much nitrogen needs to 
be in the soil to meet fully this demand of the plants. 
These questions we studied by raising tomatoes in plots 
on the forcing-house benches which were filled with a 
soil known to be practically free from available nitrogen, 
but believed to contain all other ingredients necessary 
*[Similar, though less specific, results have been obtained by the Cor- 
nell Station. See its Bulletins X., XXI., 32, 45.] : 
