CH. IV 



NURSERIES 



127 



generally speaking, with a fairly porous soil, such as 

 should be obtained for a nursery, the percolation method 

 is preferable. In a bed watered by flooding there is, 

 near the inlet of water, not only a greater rush, but also 

 a certain deposit of silt, especially if the water is at all 

 turbid, and tender seedlings are apt to be bent down 

 and even covered up. The whole bed is also apt to be 

 covered by a thin, almost impermeable layer of silt, 

 which excludes air and has to be constantly broken up. 



Plan and 



^ 



fflWW'. 



length-section of portion of a seed-bed 

 irrigated by a meandering channel 



Fig. 23. 



With the other method only the sides of the channels 

 have to be scraped with a hoe from time to time, and 

 there is no risk of the seedlings being injured either by 

 rush of water and silt or by the hoe. 



The water for irrigation has to be obtained either 

 by leading it by means of pipes or canals from a 

 neighbouring spring or watercourse or tank above 

 the level of the nursery, or by lifting it from a 

 well or from a tank, lake, or watercourse below its 

 level. The best source of supply is a perennial 

 stream or lake, tapped at a point higher than the 



