78 



JOURNAL OF THE ROYAL HORTTCnriTURATi HOCTRTY. 



The peculiarity of leguminous plants, although commented upon 

 two thousand years ago by the elder Pliny, only came to be fully 

 recognized about 1886 as being due to an indirect supply of combined 

 nitrogen. This property is destined to greatly modify our methods of 

 treating poor soils, especially those of a calcareous character, though 

 it is seldom necessary in ordinary farm practice to artificially inoculate 

 either soil or seed in the way so often suggested lately. It is worth 

 noting that although large quantities of combined nitrogen are thus 

 formed and placed at the disposal of adjacent plants or succeeding ones, 

 I have never during seventeen years' experimental work found any 

 ill results, but immense good. The amount of combined nitrogen 

 formed in this way never seems to be excessive for other plants. This 

 property of leguminous plants is of an immense value when bringing 

 neglected, poor land into cultivation, but I do not think it will have 

 great value in gardens when once they are in good " heart " (i.e. good 

 manurial condition). 



The forms in which nitrogen is combined with other elements and of 

 special importance to the cultivator are the nitrates of potash, soda, or 

 lime (in which state nearly the whole is absorbed by plants) and 

 ammonium sulphate, and in guanos and organic matter generally, the 

 latter being more or less rapidly changed to nitrates. Nitrates are 

 very soluble, diffuse readily in moist soil, are extremely liable to 

 loss by drainage, but act powerfully upon plant growth. Combined 

 nitrogen, especially the available nitrate form, has up to now been 

 the most costly of all fertilizers. This high commercial value has 

 greatly restricted its horticultural use, not an unmitigated disadvantage, 

 for there can be no doubt that although it would have been of much 

 service in many cases, it would have done harm in others. Four years 

 ago there appeared to be every prospect of an insufficient supply of 

 available nitrogen, hence the output was very limited and the price 

 high and rising. Ammonium sulphate, a bye-product from manu- 

 factures, especially gas-works, could not be indefinitely increased. The 

 utility, if not the danger, of available nitrogen becoming more and 

 more recognized, it seemed as though there w^ould be a partial famine 

 in this important substance, but scientific research has shown means 

 of obtaining any quantity from the atmosphere. The cost of manu- 

 facture is the only item to consider, and already it is upon the market 

 both as nitrate of lime and niti'olim (calcium cyanamide) at prices which 

 have compelled holders of nitrate of soda and ammonium sulphate to 

 considerably modify their views of value, and it is safe to predict greater 

 reductions. Nitrate nitrogen is a gigantic force in the hands of the 

 cultivator, but it is essential that it be used aright, otherwise it is a 

 most dangerous substance. The lower piice and the consequent ex- 

 tended use will often mean more weakened plants, more " new 

 diseases or fresh "biologic" forms of old; and more heartburnings, 

 more worry, for the hardworking but misguided cultivator. 



This question of the use of nitrate nitrogen is, T am con- 

 vinced, so impoiiant that it seems desirable to state that the danger 



