HUMUS ESSENTIAL AND TO BE SUPPLIED. 97 



323. What is the remedy ? Plainly it is, to add to the 

 soil the element or elements wanting ; that is, to apply 

 manure to the soil. 



324. It might naturally be thought that, inasmuch as 

 the atmospheric elements are furnished continually by the 

 atmosphere, it could not be necessary to supply the soil 

 with substances intended to furnish them. But then it 

 must be remembered that the atmospheric elements are 

 furnished very slowly, and it is always desirable to hasten 

 the processes of vegetation, in our short seasons. It is 

 therefore reasonable, and the experience of all agricultu 

 rists, in all temperate countries, shows it to be wise, to 

 provide an abundant supply of those substances which 

 are full of these atmospheric elements, or which serve to 

 attract them and keep them in reserve for the wants of 

 the growing plants. 



325. To the question, therefore, Is nothing ever to be 

 supplied to the soil but the mineral elements which are 

 wanting ? the answer is to be given, whenever humus is 

 not already abundant in the soil, it is to be supplied. 

 For humus furnishes directly, and also indirectly, by the 

 changes that are going 011 in it from the action of the 

 oxygen of the atmosphere and the vital power of plants, 

 the carbonic acid, ammonia and nitric acid which are 

 just as essential as the mineral elements. 



326. But how arc wild plants supplied with humus ? 

 By a process vastly too slow to meet the wants of the hus 

 bandman. The roots and leaves of the plants that have 

 died, decay and form humus for those which are to suc 

 ceed. But the supply is usually very scanty, and wild 

 plants have often a thin, meagre look, in comparison with 

 those under cultivation ; as, for example, the slender- 

 rooted wild carrot, when compared with the carrot of the 



