Soil Composition and Preparation 29 



made, by chemical treatment, immediately avail- 

 able, and in the case of dahlias are unnecessary. 

 Animal phosphates are more quickly available 

 through the action of decay than are mineral 

 phosphates, which are set free by the air and 

 water in the soil. For this reason, ground bone, 

 a substance which contains a high percentage of 

 phosphoric acid (and some nitrogen), is the best 

 medium for phosphates in the dahlia beds in 

 soils which are not originally volcanic. 



Potash is also an important factor in the 

 composition of soil for dahlias, and wood ashes 

 is the simplest and best material to mix in the 

 beds for this purpose especially ashes from 

 hardwoods such as hickory, oak, etc. 



Phosphoric acid gives the dahlia a vigorous 

 constitution a healthy root system and strong 

 stems; potassium enables the plant to withstand 

 the attacks of fungous diseases and, combined 

 with phosphates containing some of the minor 

 elements, such as nitrogen, lime, etc., forms the 

 perfectly balanced ration. 



If the soil is stony, sift it through a coarse wire 

 mesh. Tubers like the shelter of a large rock 

 in the mountains, but they do not like a stone 

 in the shoe! Stones interfere with the growth 

 of the tubers. 



If the soil is gravelly, dig it all out and replace 



