74 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY, 



matter (ash) was found to be 2*7 per cent, in the fresh substance, 

 and nearly 12^ per cent, in the material when fully dried. The 

 nitrogen is shown to be about J per cent, in the fresh fibre, and 

 nearly 1 per cent, in the fully dried substance. The Jadoo fibre 

 is, therefore, richer in organic matter and in nitrogen than the 

 famous leaf-moulds of Rambouillet and Maurepas, France, so 

 largely used in the horticultural establishments of that country. 

 But while it does not contain so much organic matter or nitrogen 

 as the Ghent heath mould, it is richer in mineral constituents. 

 The chemical composition thus given pretty clearly shows that 

 the reason of the great value of Jadoo fibre rests in the fact 

 that the organic nitrogen is readily susceptible of nitrification, 

 and so of becoming easily available to vegetation. 



Nitrates in the Soil. 



As soil fertility is of so much importance to the horticul- 

 turist in the productiveness of the garden, and as the final 

 returns may be expected to be directly proportionate to the 

 amount of nitrates which it contains, and to the facilities or 

 favourable conditions offered for the conversion of organic 

 nitrogen into ammonia and nitrates, the subject of nitrification 

 in the soil becomes one of intense interest. 



Nitric acid is a compound of nitrogen which represents the 

 form of combination in which nitrogen must be in order that 

 plants may use it as food. The organic nitrogen of the soil, as 

 well as that contained in such fertilising materials as leaf mould, 

 peat mould, stable and farmyard manure, blood, fish, rape cake, 

 vegetable and animal refuse, &c, is not in a condition to serve 

 as plant-food. To become available it must be converted into 

 ammonia and then into nitric acid. This change is accomplished 

 by certain living organisms, known as bacteria, which exist in 

 all fertile soils — the carbon of the humus being at the same 

 time oxidised to carbonic acid, whereby heat is developed. The 

 different stages of the work are apparently performed by different 

 species of bacteria. 



We are told by Professor "Warington that the final nitrifica- 

 tion of ammonia, which is a product of oxidation or decay, is 

 performed by two species of bacteria, one of which produces 

 nitrites, which the other changes into nitrates, the latter being 

 the form in which plants take up most of their nitrogenous food. 



