130 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



only to deal with nitrogen, potash, phosphorus, occasionally, 

 lime, and still more rarely iron. 



All the materials of every soil occur in three conditions : 

 first, directly soluble in water ; second, soluble in water through 

 the action of roots, which yield weak acids ; and, third, the 

 insoluble condition. The first two are the matters upon which 

 the plants must depend, since they, like animals, can only absorb- 

 their food when in an absolutely dissolved state. 



The gardener, realising to some extent these truths, ardently 

 desires to know what his soil contains, in order that he may form 

 a judgment as to its capabilities, the crops which it may bear,, 

 and the manures to apply. In his difficulty he turns to the 

 chemist for information. 



It is not my intention to scold the analytical chemist. Yet 

 in former days, and, if truth be told, too often even now he is a 

 great misleader. He uses strong acids, and dissolves parts of 

 the soil not reachable by rain or roots, and returns these as being 

 present. True, they are present, but locked up so securely that 

 fifty years must probably elapse before they can be of service to 

 the cultivator. The improved methods of analysis now used by 

 the most advanced men are rectifying this, and it is only just that 

 the cultivator should be informed what Iris plants can secure, 

 rather than what the land will deliver up to posterity. 



It is my wish to enable the gardener, without applying to the 

 analyst, to determine for himself, at home, the nature of his soil. 

 "Water-cultures have long since shown that plants cannot grow 

 in the absence of the essential foods already mentioned, and let 

 me repeat that it is only the food which is soluble that can be 

 absorbed by them ; thus the food which is not absolutely dissolved 

 is of no use whatever, and, therefore, if any of the substances 

 required are present in a totally insoluble form, growth will be 

 impossible ; for example, if Turnips are grown by water-culture, 

 the young plants use up the material stored in the seeds, and 

 then become exhausted, unless replenished. In the absence of 

 iron the puny leaves are nearly white, but if soluble iron be 

 added, in the most minute quantity, the leaves begin to turn 

 green, and develop until the iron is again exhausted. Bat the 

 addition of any other food than the essential one missing is of 

 no service whatever. Probably a plant is growing unsatis- 

 factorily, and this or that manure is added, but without effect. 



