SOIL, MANURES AND WATERING. 373 



supply moisture to the air ? These questions are fre- 

 quently asked, and seem to be uppermost in the minds 

 of many. The answer to the first is, yes, of those that 

 need it, and to the second, no. Lettuce, and most veg- 

 etables, in fact, need not be syringed, and never receive 

 water on the foliage, except once at planting. Almost 

 the entire houses are watered by sub-irrigation, but 

 there is enough moisture in the air to keep the plants 

 in a healthy growing condition, derived from transpira- 

 tion through the foliage and evaporation from the soil. 

 The necessity of supplying more moisture to the air than 

 this, for the plants above named, is not recognized. 



HOW SUB-IRRIGATION IS OPERATED. 



With plants that are transplanted one or more 

 times, sub-irrigation is begun as soon as the seed is 

 sown. Flats sixteen by twenty-four inches, and two 

 inches deep, with slatted bottoms, are used for seed 

 sowing. As soon as the seed is sown the flats are placed 

 in a shallow vat containing an inch or two of water, and 

 allowed to stand until the moisture shows on top. They 

 are then set in any convenient spot until water is again 

 required, which is not so soon as when surface watering 

 is practiced. This method of watering is followed until 

 the plants are set in the beds, or benches. Probably 

 this method of watering involves more labor than the 

 old plan, but the plants do so much better and it is so 

 much more satisfactory in every way, that it must be 

 counted as an improvement. Eeferring to experiment 

 No. 1, with lettuee, it will be seen that the results were 

 better than in the other cases. The plants in this ex- 

 periment were carried through from the beginning by 

 the two methods. The sub-irrigated were watered in 

 that manner from the time the seed was sown, while the 

 surface-watered were treated in the old way throughout 

 the experiment. In the other experiments the differ- 



