462 Report of the Horticulturist of the 



A soil mixture which had been used for forcing lettuce with 

 good results, composed of 3 parts rotted sod from a clay loam, 

 1 part sand and 1 part stable manure, was at first compared with 

 the other mixtures which were made from it by adding different 

 amounts of sand. In some later tests the amount of sand was still 

 further varied or omitted entirely. In one case sand and stable 

 manure alone were used without any loam. In another case a 

 very light sandy loam was compared with the clay loam as a basis 

 for the soil mixtures. Commercial fertilizers were also tried on 

 some of the soils, both in combination with stable manure and 

 alone. 



description of forcing house. 



The experiments were conducted in an even-span, iron-frame 

 structure 20 feet by 44 feet with sash bars 14 inches apart. The 

 house extends east and west and has sash ventilators along the en- 

 tire length of each side under the eaves and on either side of the 

 ridge. 



Witlt Crop I the benches were 6 inches deep, outside measure- 

 ment; with Crops II, III and IV they were 12 inches deep. 

 Crops I, II and III were watered entirely on the surface. Crop 

 IV was principally subwatered through tile lying on the cemented 

 bottom of the bench. 



The house is heated by 2 hot-water coils of 3^-inch pipe ex- 

 tending around it next to the wall. In the first experiment the 

 side-benches were 34 inches wide with a space of about 2 inches 

 between the benches and the wall, while 2 benches, each 38 inches 

 wide, occupied the center of the house. All benches were 5 inches 

 deep, inside measurements. The shade of the south purlin plate 

 interfered with a uniform exposure of the south side-bench to the 

 light, and the heated air rising between the sides of the house 

 and the side-benches made the soil dryer towards the wall than it 

 was in those parts of the bench nearer the walk. For these rea- 

 sons the house was fitted for Crop IV with center benches only. 

 There were 2 of these each 6 feet 7 inches wide, separated from 



