134 NATURE TEACHING 



Experiments with Manures. 



By cultivating plants in boxes or in isolated garden 

 plots, experiments may be made as to the action of the 

 various manures in common use. The soil of an ordinary 

 garden is usually fairly well supplied with all the necessary 

 constituents of plant food. In order therefore to obtain 

 immediate and striking proof of the effects of manures, 

 it is advisable to use poor soil. Sand is very convenient, 

 and, if obtainable, should be employed. In most local- 

 ities accumulations of sand suitable for the purpose can 

 be found, for instance, on the sea-beach or in beds of 

 streams. The sand used should be free from salt. Before 

 using it, therefore, it is advisable to wash it thoroughly to 

 remove the salt.* The manner of doing this will depend 

 on the facilities at hand. A convenient method is to 

 put the sand into a barrel, the bottom of which has a 

 number of holes bored in it, and to pour water on it. 

 The water will drain away through the holes, and carry 

 the salt and other soluble matters with it. 



Pure sand is a very unfavourable soil for plants, and 

 a small amount of moss litter, not more than i per cent, 

 should be added to it. 



Take four boxes, about 2 feet long, 2 feet broad, and 

 9 to 12 inches deep. Bore a few holes in the bottom of 

 each to allow of drainage. Place them, side by side in 

 a hole dug in the garden, with not more than an inch of 

 the box projecting above the surface of the soil. By so 



* Washing is unnecessary if one is reasonably sure of the 

 absence of salt ; washing is more particularly referred to in case 

 sea-sand is used. 



