62 MANAGEMENT OF THE FORCING-HOUSE. 
‘‘7, Lettuce of good quality can be grown under glass 
in an artificial soil such as we have described, with the use 
of commercial fertilizers. We are not prepared to say at 
present that its quality is as good as the best lettuce 
grown in rich, natural soil. 
‘“‘2. A crop of forcing-house lettuce, raised as above 
described, takes from the soil in roots and heads, per 
1,000 heads, not less than: 
Grams. Pounds. Ounces. 
Nitrogen. . . . 282.6 Equivalent to 3 15 Nitrate of soda 
Phosphoric acid 87.7 H I 2 Dissolved bone black. 
Potash... 5 621.0 “ 2 10 . Muriate of potash. 
‘‘3. To supply this plant food to the soil under the 
conditions of our €xperiment, it was necessary to add to 
the soil the following quantities of fertilizers per 1,000 
plants, or per 387 square feet, the area used in our ex- 
periment for 1,000 plants : 
Pounds. Ounces. Costing, cents. 
Nitrateofsoda>..:.. 4.55 - 9 13 25 
Dissolved bone black ..... 2 15 4 
Muriateofpotash <=. =... gz 8 7 
36 ” 
On the use of fresh stable manure.—All experienced 
gardeners place the greatest faith in old well-rotted stable 
manure, and uniformly avoid fresh manure. A discus- 
sion of the behavior of fresh manure in its relation to 
nitrification is made in the Connecticut report which is 
quoted above, and it seems to throw much light upon 
the craft of gardeners. A somewhat full abstract of the 
article is here given. It is known that when nitrogen 
compounds, either in the form of nitrates or occurring in 
organic matter in manures, are fully exposed to the air, 
the nitrogen may be lost as gas by the action of certain 
denitrifying microbes. It now seems probable that simi- 
lar losses, though much less in amount, may be occasioned 
in the soil by the use of fresh stable manure. Wagner 
has found that the nitrogen of well-rotted stable manure 
