10 QUEENSLAND AGRICULTURAL JOURNAL. {1 Jay., 1898. 
Agriculture. 
GREEN MANURING. 
In the seventh series of his Htudes Agronomiques, M. Grandeau, the 
Tnspector-General of the French Agricultural Experiment Stations, publishes 
some interesting notes concerning the important functions of leguminous plants 
in the fixation of nitrogen. After alluding to the discoveries made by M, 
Pasteur, who demonstrated the incessant and colossal action of bacteria, which 
had hitherto been ascribed to chemical agency, M. Grandeau briefly describes 
the character of the investigations undertaken by Hellriegel and Wilfarth, 
whose labours were suggested and influenced by the work of Pasteur. 
Hellriegel for some years cultivated various cereal and leguminous crops 
in sterilised soil, and added their necessary alimentation in the shape of 
nutritive solutions of phosphoric acid, potash, and nitrates. In the case of the 
cereals the resulting crop was distinctly in proportion to the quantity of 
ammonia placed at its disposition, and in no case did the cereals develop when 
supplied with nutritive solution in which nitrogen was absent. On the other 
hand, the leguminous plants differed extremely in their growth. In some pots 
the plants flourished, in others they barely existed, though the conditions were 
exactly similar. Upon examination, it was found that in the former case there 
were numerous nodules composed of micro-organisms upon the roots, while in 
the case of the weakly plants the nodules were absent. In 1886, Hellriegel, 
after a long series of experiments, announced to the scientific world the fact of 
the -fixation of nitrogen by the bacteria of the nodules on the roots of 
leguminous plants, and he held that this was the source whence these plants 
drew their supply of nitrogen. 
M. Grandeau goes on to give an account of the nodules of leguminous 
lants, and of the bacteria within them. It had been shown that plants of 
this kind could not exist in sterilised soil and absolutely cut off from nitrogen ; 
and, from experiments made by Dr. Nobbe, it was ascertained that the bacteria 
in the nodules of different species of leguminous plants differ essentially in 
their physiological properties, in that they form nodules easily on the roots of 
Plants of the same species as those from which they originated, while they 
ave not nearly so much influence upon allied species, and hardly any influence 
on the roots of leguminous plants of a widely removed species. 
Further knowledge is required as to the degree in which the bacteria of 
species of leguminous plants, more or less closely allied, are active in respect 
of the different species of the same family, and it is especially important to 
have more precise information on this point, as M. Grandeau remarks that 
henceforth inoculation by means of soil containing bacteria should be adopted 
in the culture of leguminous plants; but this factor, in the opinion of Dr, 
Nobbe, does not yield in importance to the proper selection of mineral 
manures. 
From the fact that leguminous plants obtain from the air, an exhaustible 
and gratuitous source, the nitrogen necessary for their development, they 
occupy an increasingly important position among cultivated crops. Varying with 
the species cultivated, the nature of the soil and the climatic conditions of the 
season, a crop of leguminous plants fixes considerable but different quantities of 
nitrogen obtained from the atmosphere. These quantities vary from 53 to 
134 Ib. per acre. Ifa leguminous crop is dug in green, the amount of nitrogen 
resulting from it, according to M. Grandean, is equivalent to a good dressing 
of nitrogenous manure—nitrate of soda, sulphate of ammonia, or farmyard 
manure. If the foliage of the plants is utilised for cattle, the stems and roots 
remaining in the ground contain enough nitrogen to ensure a full yield of 
cereals or other plants. 
