EXPERIMENTS WITH MANURES. 131 



carry the salt and other soluble matters with it. 



2. Take four boxes, about 2 feet long, 2 

 feet broad, and 9 to ] 2 inches deep. Bore a 

 few holes in the bottom of each to allow f 

 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 placing the boxes excessive 

 evaporation from the soil in them is prevent- 

 ed. A well drained spot should be selected 

 for the boxes in order to guard against water 

 accumulating under and around them. If the 

 soil is very clayey this object may be secured 

 by putting under each box a layer of small 

 stones. It is also necessary to arrange . the 

 boxes so that the drainage water from one will 

 not run under the next. Mark the boxes 

 A. B. C. and D. 



3. In all such experiments too much care 

 cannot be taken to secure uniform conditions 

 for the boxes or plots to be experimented 

 upon For instance, if one box is shaded and 

 another not, and they are treated differently 

 aa regards manuring, it is impossible to be 

 certain afterwards whether any difference in 

 their crops is due to the different manures 

 used or to the difference of lighting. 



4. Fill the boxes with the washed sand, 



