CONSTRUCTION OF HOTBEDS 



III 



lined with boards, as previously described (156). Port- 

 able frames are placed on top of the manure, which is 

 about even with the surface of the ground, and the 

 frames are then banked with manure. This plan requires 

 more manure, although the beds furnish heat for a longer 

 period, and they settle with the manure, and so the plants 

 are always the same distance from the glass. Another 

 plan often used southward and on poorly drained land 

 is to place the manure on top of the ground, and in this 

 way dispense with the pit. This requires more manure 

 than either of the plans described, because there is no 

 protection at sides and ends. Liberal space must be 



GLASS 



I.... 



"^^ y^r - ' f Z^ — - — 



FIG. 20. FLUE-HEATED FRAME 



provided for banking the frame when it is placed so high 

 above ground. Manure greenhouses are sometimes used 

 by placing hot manure under the benches; a central 

 alley is provided, so it is possible to work in the house 

 with the same convenience as in houses heated by flues, 

 steam or hot water. The plan is not recommended, be- 

 cause steam or hot water heating is more economical 

 and much more satisfactory. 



The manure from spent hotbeds has lost most of the 

 nitrogen, but it is useful for composting and fertilizing 

 crops which do not require large amounts of this ele- 

 ment. It is also useful for placing in the bottom of flats 

 'lefore transplanting. 



